JP2021196563A - Acoustic communication system, acoustic transmission device, acoustic reception device, program, and acoustic signal transmission method - Google Patents

Abstract

To provide an acoustic communication system, an acoustic transmission device, an acoustic reception device, a program, and an acoustic signal transmission method that can embed embedded information in an acoustic signal with appropriate embedding intensity in a sound electronic watermark technique.SOLUTION: An acoustic communication system 10 includes an acoustic transmission device 20 and an acoustic reception device 30. The acoustic transmission device 20 includes: an embedding unit 28 that generates an acoustic signal AS by embedding embedded information SC in an original signal OS; a sound emission processing unit 29 that causes a speaker 12 to emit the acoustic signal AS; and a compressor 24 that compresses the original signal OS before the embedded information SC is embedded. The acoustic reception device 30 includes: an extraction unit 33 that extracts the embedded information SC from the acoustic signal AS collected by a microphone 31; a display unit 17 that outputs information; and a second control unit 32 that causes the display unit 17 to output provision information corresponding to the embedded information SC extracted by the extraction unit 33.SELECTED DRAWING: Figure 4

Description

The present invention relates to an acoustic communication system, an acoustic transmitter, an acoustic receiver, a program, and an acoustic signal transmission method for transmitting information by embedding information in an acoustic signal such as a sound wave.

Patent Document 1 discloses an acoustic communication system in which information is embedded in an acoustic signal such as a sound wave by a digital watermark and transmitted. This acoustic communication system is an acoustic transmission device that emits an acoustic signal in which identification information is embedded by sound electron watermark technology from a sound emitting part such as a speaker, and an acoustic signal from a microphone that collects the emitted acoustic signal. It is equipped with an audio receiver (portable terminal) that extracts identification information from. The acoustic receiving device extracts the identification information from the acoustic signal and provides the user with the related information associated with the identification information.

Japanese Unexamined Patent Publication No. 2016-153906

By the way, the ease of reception when the acoustic receiver receives the identification information embedded in the acoustic signal with a microphone is affected by the reception environment of the acoustic receiver. Since the embedded information such as the identification information embedded in the acoustic signal by the sound electron watermark technology is a sound wave, the ease of receiving it is the distance from the sound emitting part to the sound collecting part, the direction of the sound emitting part, and the sound emitting part. The presence or absence of obstacles that hinder the transmission of sound waves from the sound receiving unit to the sound collecting unit, and the receiving environment such as noise in the area where the sound receiving device is located also have an effect. Obstacles include buildings such as steel towers, chimneys, and buildings that absorb or reflect sound. In addition, the noise in the assumed reception area includes the voice of surrounding people and the traffic noise of cars and railways. There is a problem that the ease of receiving the embedded information is affected by various factors of this kind, and a situation in which reception omission is likely to occur occurs. On the other hand, if the sound intensity of the embedded information is increased, the reception omission of the embedded information can be reduced, but if the sound intensity of the embedded information is too large, the hiding characteristics of the embedded information deteriorate, and the announcement voice, music, etc. There is a problem that it becomes difficult to hear the original sound of. In addition, if the volume of the original sound is increased, the sound intensity of the embedded information can be increased accordingly, but the announcement voice and the like heard by the receiving user may become noisy or cracked. There is also a limit.

Therefore, we provide an acoustic communication system, an acoustic transmitter, an acoustic receiver, a program, and an acoustic signal transmission method that can suppress reception omission of embedded information embedded in the acoustic signal even if the acoustic signal is emitted at an appropriate volume. ..

Hereinafter, means for solving the above problems and their actions and effects will be described.
(1) An acoustic communication system that solves the above problems is an acoustic transmission device having a sound emitting unit that emits an acoustic signal in which embedded information is embedded, and an acoustic reception device having a sound collecting unit that collects the acoustic signal. An acoustic communication system including a device, wherein the acoustic transmission device has an embedded unit that embeds embedded information in the original sound signal to generate an acoustic signal, and a sound emitting unit that emits the acoustic signal from the sound emitting unit. The sound receiving device includes a sound processing unit and a compressor that compresses the original sound signal before the embedded information is embedded or the acoustic signal before being emitted from the sound emitting unit, and the sound receiving device is the sound collecting unit. An extraction unit that receives the embedded information by extracting the embedded information from the sound picked up by the sound, an output unit that outputs the information, and the output unit that provides information corresponding to the embedded information extracted by the extraction unit. It is equipped with a control unit for outputting to.

According to this configuration, the original sound signal before the embedded information is embedded or the acoustic signal before being emitted from the sound emitting part is compressed by the compressor, so that the sound intensity (volume) of the acoustic signal is not noisy and the sound is sounded. Can be raised without cracking. Therefore, since the sound intensity (embedding intensity) of the embedded information embedded in the acoustic signal is also increased, it is possible to suppress the reception omission of the embedded information in the acoustic receiving device.

(2) The acoustic communication system may include an amplification unit that amplifies the original sound signal compressed by the compressor or the acoustic signal.
According to this configuration, the original sound signal before the embedded information is embedded or the acoustic signal before being emitted from the sound emitting unit is compressed by the compressor. Further, the compressed original sound signal or acoustic signal is amplified by the amplification unit. Therefore, the sound intensity (volume) of the acoustic signal can be increased by amplification without being noisy and without cracking. Therefore, since the sound intensity of the embedded information embedded in the acoustic signal is also increased, it is possible to suppress the reception omission of the embedded information in the acoustic receiving device.

(3) In the acoustic communication system, the compressor compresses the original sound signal or a portion exceeding the threshold value of the acoustic signal at a predetermined compression rate, and does not compress the portion below the threshold value or exceeds the predetermined compression rate. It may be compressed with a small compression ratio.

According to this configuration, the portion of the original sound signal or the acoustic signal that exceeds the threshold value is compressed at a predetermined compression rate, and the portion below the threshold value is not compressed or is compressed at a compression rate smaller than the predetermined compression rate. Therefore, when the sound intensity (volume) of the acoustic signal is increased, the original sound having the maximum amplitude is not noisy and the sound is not cracked, and the sound intensity (amplitude) of the original sound below the threshold value can be increased. Therefore, the sound intensity (embedding intensity) of the embedded information that is hidden and embedded in the original sound can be increased to suppress reception omission.

(4) In the acoustic communication system, the compressor may adjust at least one of the threshold value and the compression rate.
According to this configuration, at least one of the threshold value and the compression rate is adjusted, so that it is possible to increase the sound intensity of a small original sound that is not desired to be compressed or is desired to have a small compression rate. For example, by adjusting the threshold value, it is possible to select a portion that is desired to be greatly compressed and a portion that is not. Further, by adjusting the compression rate, the compression rate of the portion of the original sound signal or the acoustic signal that exceeds the threshold value can be adjusted, so that the sound intensity of the original sound below the threshold value can be increased while suppressing the deterioration of the sound quality due to the compression. ..

(5) In the acoustic communication system, the threshold value may be set to a value larger than the embedding strength when the embedding portion embeds the embedding information.
According to this configuration, the threshold value is set to a value larger than the embedding strength when the embedding portion embeds the embedding information, so that the small original sound of the target original sound to which the embedding information is embedded is not compressed or is not compressed. It requires weaker compression than other original sounds. Therefore, when the acoustic signal is emitted at an appropriate volume, the sound intensity of the smaller original sound can be effectively increased compared to before compression, and the sound intensity of the embedded information embedded in the original sound is increased accordingly. can do. Therefore, it is possible to suppress reception omission of embedded information in the acoustic receiving device.

(6) In the acoustic communication system, the embedded unit may detect an original sound having an amplitude equal to or higher than a set value among the input original sound signals, and may embed the embedded information in the detected original sound.

According to this configuration, the embedding unit detects the original sound having an amplitude equal to or higher than the set value among the input original sound signals, masks the detected original sound, and embeds the embedded information. Therefore, since the embedded information is embedded in the relatively large original sound having an amplitude equal to or larger than the set value, the sound intensity of the embedded information can be increased. As a result, it is possible to suppress reception omission of embedded information in the acoustic receiving device.

(7) In the acoustic communication system, the acoustic transmission device changes the compression condition of the compressor, and the sound emission processing unit emits an acoustic signal in which the embedded information including the compression information related to the compression condition is embedded. The sound receiving device includes a test mode for emitting sound from the sound unit, the sound receiving device includes an output unit that outputs compressed information included in the embedded information extracted by the extracting unit, and the sound transmitting device has the output unit. The compressor may be provided with a first control unit for inputting the output compression information and compressing the original sound signal or the acoustic signal under compression conditions based on the compression information.

According to this configuration, the acoustic transmitter can obtain the compressed information suitable for reception based on the embedded information received on the acoustic receiver side in the test mode. Therefore, the acoustic transmission device can compress the original sound signal or the acoustic signal under appropriate compression conditions based on the received compression information. Therefore, it is possible to suppress the omission of the embedded information S reception in the sound receiving device.

(8) In the acoustic communication system, the acoustic receiving device is provided in a portable information terminal having a display unit as the output unit, the display unit displays the compressed information, and the acoustic transmitting device displays the compressed information. It is provided with an input operation unit for inputting the compression information displayed by the display unit.
The first control unit may compress the original sound signal or the acoustic signal in the compressor under compression conditions determined based on the input compression information.

According to this configuration, the embedded information received in the test mode is displayed on the display unit, and the displayed compressed information is input to the sound transmission device by the operation of the input operation unit. In the acoustic transmission device, the first control unit determines an appropriate compression condition based on the compression information. The first control unit causes the compressor to compress the original sound signal or the acoustic signal under appropriate compression conditions. Therefore, even if the acoustic transmitting device emits an acoustic signal from the sound emitting unit at an appropriate volume, it is possible to suppress reception omission of the embedded information in the acoustic receiving device.

(9) In the acoustic communication system, the acoustic receiving device is provided in a portable information terminal having a transmitting unit and an antenna as the output unit, and the transmitting unit outputs the compressed information from the antenna by wireless communication. The acoustic transmission device includes an antenna and a receiving unit for receiving the compressed information output by the antenna by wireless communication, and the first control unit is said to have the compression conditions determined based on the received compression information. The compressor is made to compress the original sound signal or the acoustic signal.

According to this configuration, in an acoustic transmission device that receives compressed information transmitted by wireless communication from a portable information terminal, the first control unit sets the compressor under appropriate compression conditions determined based on the received compression information. The original sound signal or acoustic signal can be compressed. Therefore, even if the acoustic signal is emitted at an appropriate volume, it is possible to suppress the reception omission of the embedded information in the acoustic receiving device.

(10) In the acoustic communication system, the acoustic receiving device is provided in a portable information terminal having a position information acquisition unit for acquiring its own position information, and the output unit receives the compression information and the position information. Output, the acoustic transmission device inputs or receives the compression information and the position information output by the output unit, and the first control unit determines the compression condition based on the compression information and the position information. You may.

According to this configuration, the acoustic transmitter inputs or receives the compression information and the position information output by the output unit of the acoustic receiver, and the first control unit determines appropriate compression information based on the compression information and the position information. do. Even if the acoustic signal is emitted from the sound emitting unit at an appropriate volume, the acoustic receiving device can suppress reception omission of the embedded information embedded in the acoustic signal.

(11) In the acoustic communication system, the acoustic transmission device includes an encoding unit that encodes information including the compressed information into embedded information, and the embedded unit uses the embedded information as the embedded information. The extraction unit that is embedded in the original sound signal may include a decoding unit that decodes the embedded information extracted from the acoustic signal into information including the compression information.

According to this configuration, since the embedded information is embedded in the original sound signal by the diffusion method, it is possible to suppress the adverse effect of the embedded information on the hearing of the original sound as much as possible.
(12) The acoustic transmission device that solves the above-mentioned problems is the acoustic transmission device in the acoustic communication system, in which an embedded unit that embeds embedded information in the original sound signal to generate an acoustic signal and the acoustic signal. It includes a sound emitting processing unit that emits sound from the sound emitting unit, and a compressor that compresses the original sound signal before the embedded information is embedded or the acoustic signal before being emitted from the sound emitting unit. According to this configuration, the same operation and effect as those of the acoustic transmission device constituting the acoustic communication system can be obtained.

(13) The acoustic receiving device for solving the above problems is the acoustic receiving device in the acoustic communication system, from the sound collecting unit that collects the acoustic signal and the acoustic signal collected by the sound collecting unit. The extraction unit for extracting the embedded information, the determination unit for determining whether the information contained in the embedded information extracted by the extraction unit is identification information or the compressed information, and the determination result of the determination unit are In the case of the compressed information, the compressed information in the embedded information extracted by the extraction unit is output to the first output unit, and when the determination result of the determination unit is the identification information, the identification information is used. It includes a control unit that outputs the corresponding provided information to the second output unit. According to this configuration, the same operation and effect as those of the acoustic receiving device constituting the acoustic communication system can be obtained.

(14) The program for solving the above-mentioned problem is a program to be executed by a computer included in the acoustic transmission device in the acoustic communication system, and the computer embeds embedded information in the original sound signal to generate an acoustic signal. The embedded portion, the sound emitting processing unit that emits the acoustic signal from the sound emitting unit, the original sound signal before the embedded information is embedded, or the acoustic signal before being emitted from the sound emitting unit is compressed. The compressor functions as an amplifying unit that amplifies the original sound signal after compression or the acoustic signal after compression before being emitted from the sound emitting unit. According to this program, by causing a computer to execute the program, the same operation and effect as that of the sound transmission device can be obtained.

(15) The program for solving the above problem is a program to be executed by a computer included in the sound receiving device in the sound communication system, and the computer receives embedded information from the sound signal picked up by the sound collecting unit. When the extraction unit to be extracted, the determination unit for determining whether the information contained in the embedded information extracted by the extraction unit is identification information or compression information, and the determination result of the determination unit are the compression information. Outputs the compressed information in the embedded information extracted by the extraction unit to the first output unit, and when the determination result of the determination unit is the identification information, provides the provided information corresponding to the identification information. 2 It functions as a control unit that outputs to the output unit. According to this program, by causing a computer to execute the program, the same effect as that of the sound receiving device can be obtained.

(16) In the acoustic signal transmission method for solving the above problems, the acoustic receiver receives the acoustic signal transmitted by the acoustic transmitter by emitting the acoustic signal in which the embedded information is embedded from the sound emitting unit. A method of transmitting an acoustic signal that is received by collecting sound in a sound unit, wherein the acoustic transmission device embeds embedded information in the original sound signal to generate an acoustic signal, and the acoustic transmission device is described. A sound emitting step for emitting a sound signal from the sound emitting unit, an extraction step for the sound receiving device to extract the embedded information from the acoustic signal collected by the sound collecting unit, and the sound receiving device. The sound transmission device includes the original sound signal or the sound emission before the embedded information is embedded, including a control step for outputting the provided information corresponding to the embedded information extracted in the extraction step to the output unit. A compression step for compressing the acoustic signal before being emitted from the unit is further provided. According to this acoustic signal transmission method, the same effect as that of the acoustic communication system can be obtained.

According to the present invention, even if the acoustic signal is emitted at an appropriate volume, it is possible to suppress reception omission of the embedded information embedded in the acoustic signal.

The schematic diagram which shows the acoustic communication system of 1st Embodiment. A graph showing the compression ratio of the compressor. The schematic diagram which shows the acoustic communication system. The block diagram which shows the structure of an acoustic communication system. (A) to (c) are graphs explaining the compression process of the original sound signal. (A) is a graph showing an acoustic signal without compression, and (b) is a graph showing an acoustic signal with compression. A graph illustrating the echo diffusion method. The graph explaining the adjustment method of the embedding strength in the echo diffusion method. The schematic diagram which shows an example of the acoustic communication system in 2nd Embodiment. The schematic diagram which shows the compression information displayed on the display part of an information terminal. The schematic diagram which shows the other example of the acoustic communication system. The block diagram which shows the structure of an acoustic communication system. A flowchart showing an acoustic signal transmission process. The block diagram which shows the structure of the acoustic transmission device in the modification example. The graph which shows the compression ratio of the compressor in the modification example.

Hereinafter, the acoustic communication system 10 of the present embodiment will be described with reference to FIGS. 1 to 8.
As shown in FIG. 1, the acoustic communication system 10 picks up an acoustic transmission device 20 having a speaker 12 as an example of one or a plurality of sound emitting units, and an acoustic signal AS emitted from the speaker 12. It includes an audio receiving device 30 built in an information terminal 15 having a microphone 31 (see FIG. 2) as an example of a sound collecting unit for receiving). Embedded information SC (see FIG. 2) is embedded in the acoustic signal AS by sound digital watermarking technology. The user carries a portable information terminal 15 and moves around. When the user positions the acoustic signal AS emitted from the speaker 12 within a predetermined area that can be picked up by the microphone 31, the acoustic receiver 30 built in the information terminal 15 is embedded in the acoustic signal AS. Receive the embedded information SC.

For example, when the user carries the information terminal 15 and is located within the assumed reception area assumed for the purpose of providing the provided information to the user by a broadcasting entity such as a station, a shopping district, or a public facility. In addition, the embedded information embedded in the acoustic signal AS broadcast from the speaker 12 by the sound digital watermarking technique is received. The information terminal 15 is, for example, a mobile phone, a smartphone, a notebook computer, or the like. The sound receiving device 30 acquires the provided information provided by the broadcasting subject based on the embedded information SC embedded in the sound signal AS. In this way, the user who uses the sound receiving device 30 can receive the provided information provided by the broadcasting subject.

The broadcasting subject is, for example, a person or a business operator who broadcasts the acoustic signal AS, or a person or a business operator who requests the broadcasting of the acoustic signal AS. The broadcasting subject may be a person or a business operator who forms the acoustic signal AS by himself / herself. The broadcaster does not have to be a person or a business operator who forms the acoustic signal AS by himself / herself. For example, broadcasters are businesses that operate stores, businesses that operate public transportation such as railways, businesses or groups of learning facilities including schools, businesses that operate museums and exhibitions, pools, etc. Businesses that operate leisure facilities, businesses that operate accommodation facilities, local governments that broadcast disaster warnings, etc.

The provided information is information provided by the broadcaster to the user. The storage location of the provided information is not limited. In one example, the provided information is stored in a server on the Internet IN. In another example, the provided information is stored in the acoustic receiver 30. The following is an example of the information provided. In the case of a business operator whose broadcasting entity operates a store, the provided information is the detailed contents of the products in the store. If the broadcaster is a municipality, the information provided is a map showing where to evacuate in the event of a disaster. If the broadcaster is the operator of the exhibition, the information provided is information that indicates the details of the exhibit. The provided information may be an announcement obtained by translating an announcement broadcast as an acoustic signal AS into another language. When the broadcasting subject is a movie theater, the provided information may be subtitles of the dialogue of the movie. The provided information may be link information (for example, URL: Uniform Resource Locator) indicating a place where detailed information is stored. In this embodiment, the provided information is provided as a URL on the Internet IN. The provided information may be displayed on the display unit 17 of the information terminal 15 (see FIG. 3), may be emitted from headphones or earphones connected to the earphone jack of the information terminal 15, or may be emitted from the speaker of the information terminal 15. It may be emitted.

The acoustic signal AS is a sound wave including frequencies in the audible range. The embedded information SC is embedded in the acoustic signal AS by a digital watermark. The acoustic signal AS is broadcast from the broadcasting device 11 provided with the acoustic transmitting device 20. Examples of acoustic signals AS include announcements, alarms, general or visually impaired sound signs, BGM (background music), explanatory audio output at museums and exhibitions, and program broadcasts.

As shown in FIG. 3, the acoustic transmission device 20 includes a device main body 20A and a speaker 12 connected to the device main body 20A. The acoustic transmission device 20 emits an acoustic signal AS generated by embedding the embedded information SC in the original sound signal OS (see FIG. 4) by a digital watermark from the speaker 12.

The acoustic signal AS is composed of an original sound signal OS composed of voice or music, and a plurality of embedded information SCs embedded in the original sound signal OS at predetermined time intervals. Since the embedded information SC is hidden by the sound digital watermarking technology, the embedded information SC is embedded with a sound intensity smaller than the sound intensity of the original sound so as to be hidden by the original sound such as the announcement voice in the acoustic signal AS.

The sound receiving device 30 includes a microphone 31 as an example of a sound collecting unit. The sound receiving device 30 extracts a plurality of embedded information SCs from the sound signal AS picked up by the microphone 31. Here, if the ratio of the sound intensity α of the embedded information SC to the sound intensity (for example, unit intensity “1”) of one original sound OS1 in the acoustic signal AS is too large, the hiding performance deteriorates and the announcement voice or the like is produced. The original sound signal OS becomes difficult to hear. On the other hand, if the ratio of the sound intensity α of the embedded information SC to the sound intensity of one original sound OS1 in the acoustic signal AS is too small, the hiding characteristics are enhanced and the original sound signal OS such as the announcement voice is easy to hear, but it is embedded. The reception characteristics of the information SC deteriorate, and the frequency of reception omissions of the embedded information SC increases.

Therefore, in order to achieve both the hiding characteristics and the receiving characteristics, it is important to set the ratio of the sound intensity αk of the embedded information SC to the sound intensity of the original sound OS1 to an appropriate value. However, even if the ratio of the sound intensity αk of the embedded information SC to the sound intensity of the original sound OS1 is determined, if the sound intensity of the original sound OS1 is small, the sound intensity αk of the embedded information SC also becomes small accordingly. In order to solve this, the sound intensity of the original sound OS1 may be increased, but the user may feel noisy. Further, if the volume (sound intensity) of the original sound OS1 is raised too much, the limit of the speaker 12 may be exceeded, and sound cracking may occur, making it difficult to hear the original sound. Therefore, it is desired that the sound intensity of the embedded information SC can be increased even if the volume is appropriately increased without exceeding the limit of the speaker 12.

The sound receiving device 30 includes a microphone 31 as an example of a sound collecting unit. The sound receiving device 30 extracts a plurality of embedded information SCs from the sound signal AS picked up by the microphone 31. Here, if the sound intensity of the embedded information SC is too low with respect to the sound intensity (for example, unit intensity "1") of one original sound OS1 in the acoustic signal AS, the reception characteristic of the embedded information SC deteriorates, and the embedded information The frequency of SC reception omissions increases.

The ease of reception when the sound receiving device 30 receives the embedded information SC embedded in the sound signal AS with the microphone 31 is affected by the receiving environment of the sound receiving device 30. The embedded information SC such as the identification information embedded in the acoustic signal AS by the sound digital watermarking technique is a sound wave. Therefore, the ease of receiving the embedded information SC is determined by the presence or absence of obstacles that hinder the transmission of sound waves between the speaker 12 and the sound receiving device 30, in addition to the distance from the speaker 12 to the microphone 31 and the orientation of the speaker 12. (Easy transmission of sound waves), the environment related to noise such as noise in the surrounding area of the sound receiving device 30 has an influence. Examples of noise include human speech, traffic noise, and other broadcast sounds around a user carrying an information terminal 15 having a built-in sound receiving device 30. In addition, obstacles include buildings such as steel towers, chimneys, and buildings that absorb or reflect sound. Further, even if the speaker 12 is oriented toward the assumed reception area RA, the ease of receiving the embedded information SC may differ depending on the position in the assumed reception area RA. When the ease of receiving the embedded information SC changes due to various factors of this kind and the ease of receiving the embedded information SC decreases, reception omission is likely to occur.

The acoustic signal AS is adjusted to an appropriate sound intensity (volume) that is easy for the user carrying the information terminal 15 to hear. The acoustic transmission device 20 of the present embodiment compresses and smoothes the original sound signal OS, and then increases the volume of the acoustic signal AS within a range of sound intensity appropriate for the user. As a result, the sound intensity of the original sound included in the original sound signal OS is relatively increased. Therefore, the number of original sounds having an amplitude (sound intensity) equal to or larger than the set value to be embedded in the embedded information SC in the original sound signal OS is increased. Therefore, the sound intensity (embedding intensity) of the embedded information SC embedded with the sound intensity of the original sound and the sound intensity of a certain ratio can be relatively increased. In addition, the number of original sounds that can be embedded in the embedded information SC increases, and the embedding time interval of the embedded information SC can be shortened.

The acoustic transmission device 20 shown in FIG. 3 amplifies the original sound signal OS compressed under the determined compression conditions, and then has a sound intensity (embedded intensity) at a constant ratio to the sound intensity of the original sound in the original sound signal OS. The identification information ID (see FIG. 4) is embedded as the embedded information SC to generate an acoustic signal Sas. Then, the acoustic transmission device 20 emits an acoustic signal AS from the speaker 12 based on the acoustic signal Sas. As a result, the acoustic transmission device 20 transmits the acoustic signal AS in which the embedded information SC is embedded in the information terminal 15 carried by the user in the assumed reception area. The information terminal 15 in the assumed reception area can reliably receive the identification information ID embedded as the embedded information SC in the acoustic signal AS.

Next, the configuration of the sound transmitting device 20 and the sound receiving device 30 will be described with reference to FIG. The sound transmission device 20 may be configured as a single unit, but is provided in, for example, the broadcasting device 11 shown in FIG. The broadcasting device 11 includes an input operation unit 14 such as a keyboard or an operation panel for an operator performing a broadcasting operation to perform an input operation. Further, the sound receiving device 30 is provided in the information terminal 15. In this embodiment, the sound wave is referred to as an acoustic signal AS and the electrical signal is referred to as an acoustic signal Sas in order to distinguish between a sound signal generated by a sound wave transmitted in space and an electric signal. Further, the original sound signal OS is an electric signal. Further, in the embedded information SC, what is embedded in the acoustic signal AS is a sound wave, and what is embedded in the acoustic signal Sas is an electric signal.

First, the sound transmission device 20 will be described. The sound transmission device 20 includes a first input unit 21 for inputting an original sound signal OS (see, for example, FIG. 5A), and a second input unit 22 for inputting an identification information ID. The sound transmission device 20 includes a first control unit 23 that collectively controls the sound transmission device 20. The first control unit 23 outputs the identification information ID to the encoding unit 27.

Further, the acoustic transmission device 20 includes a compressor 24 that compresses the original sound signal OS, and an amplifier 25 as an example of an amplification unit that amplifies the compressed original sound signal OS (for example, see FIG. 5B). Further, the acoustic transmission device 20 has a diffusion code generator 26, an encoding unit 27, and an embedded unit 28 having a function of convolving the embedded information SC into the amplified original sound signal OSa (see, for example, FIG. 5C). And prepare. Further, the acoustic transmission device 20 is a sound emission processing unit that emits an acoustic signal AS from the speaker 12 based on the acoustic signal Sas (for example, FIG. 6B) in which the embedded information SC by the embedded unit 28 is embedded. 29 is provided.

The first control unit 23 adjusts the compression conditions of the original sound signal OS to be compressed by the compressor 24. Further, the first control unit 23 adjusts the amplification factor for amplifying the compressed original sound signal OS to the amplifier 25. Further, the first control unit 23 instructs the embedded unit 28 of the set value. The embedded unit 28 has a function of detecting an original sound having an amplitude of a set value or more among a plurality of original sounds in the original sound signal OS. Then, the embedded unit 28 embeds the compressed information CD or the embedded information SC in which the identification information ID is encoded by the encoding unit 27 in the detected original sound.

Here, the function of the compressor 24 will be described with reference to FIG.
FIG. 2 is a graph showing compression conditions by the compressor 24. The horizontal axis shows the sound intensity before compression, and the vertical axis shows the sound intensity after compression. This graph shows the relationship between the sound intensity before compression and the sound intensity after compression. Here, the compression conditions include a threshold value SH (threshold value) and a ratio (ratio). The compressor 24 compresses the sound intensity at a level exceeding the threshold value SH at a specified ratio β (ratio). In this example, the ratio β is also referred to as the compression ratio β. In the present embodiment, the threshold value SH is set to a constant value, and the compression rate β is changed. The compression rate β is set to a value (0 ≦ β ≦ 1) within the range of 0 or more and 1.0 or less. In the graph, the compression rate β = 0, 0.2, 0.4, 0.6, 0.8, 1.0 is set. The compression rate β = 0 corresponds to a process of cutting the sound intensity at a level exceeding the threshold value SH. Further, the compression rate β = 1.0 corresponds to the process of not compressing.

In this example, different compression rates β are set in a plurality of stages in the measurement mode, which is the test mode. For example, the different compression rates β are set in 6 stages of β = 0, 0.2, 0.4, 0.6, 0.8, and 1.0. The steps of different compression rates β may be 9 steps in which values for each 0.1 are set in the range of β = 0.1 to 0.9, and of the compression rates β = 0 and β = 1. It may be in multiple stages with both or one added. Further, the different compression rates β may be two-step or three-step.

Further, the compression rate β may be a ratio represented by “a: b”. For example, the compression rate β = 1 may be expressed as “1: 1”, the compression rate β = 0.5 may be expressed as “2: 1”, and the compression rate β = 0.25 may be expressed as “4: 1”. For example, β = “1: 1”, “2: 1”, “3: 1”, “4: 1”, and “5: 1” may be set as different compression ratios β. In addition, the compression rate β may be expressed by other than these. Regardless of which expression is used, if the compression rate β is substantially directly or indirectly indicated, it corresponds to the compression rate β as used herein.

Further, as another compression condition, the compression rate β may be set to a constant value and the threshold value SH may be changed. For example, the compression rate β = 0.3, and the threshold value SH is changed to the threshold values SH1, SH2, ..., SHn. The threshold value SH is set to, for example, five stages of threshold values SH1, SH2, SH3, SH4, and SH5. Here, the thresholds SH1 to SH5 have a relationship of SH1 <SH2 <SH3 <SH4 <SH5. In the graph shown in FIG. 2, PS corresponds to the maximum embedding intensity, which is the maximum sound intensity of the embedding information SC. The purpose of compressing the original sound signal OS is to increase the sound intensity of the original sound to be embedded in the embedded information SC, so that the sound intensity is a fixed ratio (for example, less than 1.0) to the sound intensity of the original sound. Since the purpose is to increase the sound intensity of the embedded information SC, the threshold SH is set in a range exceeding the maximum embedded intensity PS. When the diffusion method is adopted, since the constant ratio is 0.5 or less, the threshold value SH is set in a range more than twice the maximum embedding strength PS.

The first control unit 23 controls the compressor 24 so as to compress the original sound signal OS under the compression conditions stored in the memory in advance, and amplifies the compressed original sound signal OS at the amplification factor stored in the memory in advance. It controls the amplifier 25. Further, the first control unit 23 may input the amplification condition data and the amplification factor data from the external memory or the server. Further, the first control unit 23 controls the compressor 24 based on the compression conditions set by the operator by operating the operation unit for adjusting the compression conditions provided in the acoustic transmission device 20, and is used for adjusting the amplification conditions. The amplifier 25 may be controlled based on the amplification factor set by the operator operating the operation unit. The operation unit for adjusting the amplification condition may be, for example, a volume control unit. In this example, the function of the amplifier 25 to amplify the compressed original sound signal OS corresponds to a part of the function of raising the volume of the acoustic signal AS. In a configuration in which the sound transmitting device 20 or the broadcasting device 11 includes a volume adjusting operation unit and a volume adjusting unit for adjusting the volume of the sound signal AS, the amplifier 25 may not be provided.

The diffusion code generator 26 shown in FIG. 4 generates a diffusion code. The diffusion code may be any code. For example, the PN sequence is used as the diffusion code. The PN sequence is a sequence called Pseudo-Noise Sequence: pseudo-noise sequence. The encoding unit 27 encodes (encodes) the identification information ID into the embedded information SC using a diffusion code.

The embedding unit 28 embeds the embedded information SC in the original sound signal OS by convolving the embedded information SC in the original sound signal OS. The original sound signal OS is, for example, an audio signal such as an announcement or a music signal such as BGM. The original sound signal OS of this example functions as a transmission medium (carrier wave) for transmitting the embedded information SC. Further, the original sound signal OS of this example has a frequency in the audible range. The original sound signal OS may have a frequency in the non-audible range.

The method in which the embedding unit 28 folds the embedding information SC into the original sound signal OS and embeds it is a diffusion method by a diffusion method. This diffusion method is particularly an echo diffusion method or a spread spectrum method. The embedding method may be another method. It is preferable to adopt a diffusion method in which the diffusion code of the PN sequence functions as a secret key in terms of enhancing the confidentiality of the embedded information SC.

The sound emission processing unit 29 emits an acoustic signal AS from the speaker 12 based on the acoustic signal Sas. The identification information ID is embedded in the acoustic signal AS as the embedded information SC.
The sound transmission device 20 includes an electronic board on which a CPU, a memory, and the like are mounted. A program for acoustic signal generation processing is stored in the memory. By executing the program read from the memory by the CPU, each part 23 to 29 made of software is configured in the sound transmission device 20. A computer is composed of a CPU and memory. Then, the program stored in the memory in the sound transmission device 20 uses the computer as a first control unit 23, a compressor 24, an amplifier 25, a diffusion code generator 26, an encoding unit 27, an embedded unit 28, and a sound emitting processing unit. Make it function as 29. Each unit 23 to 29 may be configured by software and hardware, or may be configured by hardware.

Next, the sound receiving device 30 will be described with reference to FIG.
The acoustic receiving device 30 includes a microphone 31 that functions as an example of a sound collecting unit that collects an acoustic signal AS, and a receiving circuit (not shown) that converts the acoustic signal AS collected by the microphone 31 into an acoustic signal Sas that is an electric signal. And. Further, the sound receiving device 30 includes a second control unit 32 that collectively controls the sound receiving device 30. The receiving circuit may be provided in the information terminal 15.

The acoustic receiving device 30 includes an extraction unit 33 and a decoding unit 34 that extract the embedded information SC from the acoustic signal Sas input from the receiving circuit. The embedded information SC is a coded identification information ID. In this embodiment, the extraction unit 33 and the decoding unit 34 constitute an example of the extraction unit.

The extraction unit 33 extracts the embedded information SC from the acoustic signal Sas by a method corresponding to the diffusion method of the sound digital watermarking method. When the sound digital watermarking method is the echo diffusion method, the extraction unit 33 extracts the embedded information SC diffused on the time axis as the echo of the original sound included in the original sound signal OS from the acoustic signal Sas. Specifically, the extraction unit 33 extracts the embedded information SC by performing cepstrum conversion on the acoustic signal Sas. When the sound digital watermarking method is a spread spectrum method, the extraction unit 33 demodulates the embedded information SC spectrum-spread to the original sound included in the original sound signal OS to obtain the embedded information SC from the acoustic signal Sas. Extract. When the sound digital watermarking method is another method, the extraction unit 33 performs extraction processing according to the other method to extract the embedded information SC from the acoustic signal Sas. The details of the echo diffusion method will be described later.

The decoding unit 34 decodes the embedded information SC into the identification information ID. The decoding unit 34 decodes the embedded information SC into the identification information ID by performing reverse diffusion with respect to the diffusion adopted by the encoding unit 27. Specifically, the decoding unit 34 cross-correlates the embedded information SC with the same PN sequence as the PN sequence diffused by the embedded unit 28, so that the embedded information SC is identified before encoding. Decrypt to ID. The decoding unit 34 sends the decoded identification information ID to the second control unit 32.

When the second control unit 32 shown in FIG. 4 inputs the received identification information ID, the second control unit 32 refers to the reference table 36 stored in the memory 35. The reference table 36 is table data in which the identification information ID and the provided information are associated with each other. The identification information ID has, for example, a predetermined amount of information (for example, 8 bits) in the range of several bits to several bits. The identification information ID can be set to, for example, a predetermined type (for example, about 500 types) within the range of 10 to 10,000 types according to the amount of information (number of bits). When the second control unit 32 inputs the identification information ID decoded by the decoding unit 34, the second control unit 32 refers to the reference table 36 based on the identification information ID and acquires the provided information corresponding to the identification information ID.

Then, the second control unit 32 displays the provided information on the display unit 17, and emits the provided information from the headphones or earphones connected to the earphone jack of the information terminal 15, or the speaker. Specific examples of the provided information are as described above. For example, the display unit 17 displays a list of products in the store, coupon acquisition information, point acquisition information, a map, a translation of an announcement, and the like. In addition, the earphones or speakers emit explanation announcements of exhibits, guidance voices, translated voices of announcement voices, and the like.

The information terminal 15 provided with the sound receiving device 30 includes an electronic board on which a CPU, a memory, and the like are mounted. A computer is composed of a CPU and a memory 35. A program for acoustic signal reception processing is stored in the memory 35. This program is, for example, an application installed on the information terminal 15 via the Internet IN. By executing the program read from the memory by the CPU, each part 32 to 34, 37 made of software is configured in the sound receiving device 30. That is, the program stored in the memory 35 in the sound receiving device 30 causes the computer to function as each unit 32 to 34, 37. Specifically, the program stored in the memory in the sound receiving device 30 causes the computer to function as a second control unit 32, an extraction unit 33, a decoding unit 34, a determination unit 38, a transmission unit 39, and a display processing unit 37. In addition, each part 32 to 34, 38, 39 may be configured by software and hardware, or may be configured by hardware.

Next, an embedding method for embedding the embedding information SC will be described with reference to FIGS. 7 and 8. 7 and 8 show the original sound by the echo diffusion method and the echo kernel. As shown in FIG. 7, the time axis is divided into a plurality of time frames from the offset time with an offset time Δt for the original sound OS1 of the echo, and “0” and “1” are used for the plurality of time frames using the PN sequence. Multiple peaks are located at different time differences corresponding to each of the two values. α1 is the embedding strength when the diffusion length L is set, where the sound intensity of the original sound OS1 is the unit strength “1”. That is, α1 is the amplitude of the peak of the PN sequence forming the echo. In the echo diffusion method, the same detection accuracy is ensured even if the embedding intensity α1 is set to 1 / L with respect to the embedding intensity of the single echo in the echo method. The embedding information SC shown in FIG. 5 having such an embedding strength α1 is referred to as a standard embedding information SC1.

The embedding process of the sound digital watermark is performed by the embedding unit 28 convolving the original sound OS1 and the echo kernel. At the time of detection, the extraction unit 33 performs cepstrum conversion on the acoustic signal AS in which the embedded information SC is embedded in the original sound signal OS. On the other hand, when the spread spectrum method is adopted, the embedded unit 28 spreads the PN sequence in an occupied band several tens of times as large as that of the carrier wave before modulation. At the time of detection, the extraction unit 33 performs reverse diffusion and demodulates the embedded information SC to extract the information.

FIG. 8 shows the original sound OS1 and the echo kernel by the echo diffusion method in the example of the embedding information SCm adjusted to the embedding strength m · α1 which is m times the standard embedding strength α1 (FIG. 7). .. The embedding strength m · α1 of the embedding information SCm is adjusted to m times the standard embedding strength α1 shown in FIG. In the present embodiment, this m-fold adjustment is performed by compressing the original sound signal OS by the compressor 24 at a specified compression rate and amplifying the compressed original sound signal OS by the amplifier 25 at a specified amplification factor. This is performed by greatly adjusting the sound intensity of the original sound OS1 included in the OS. That is, assuming that the sound intensity of a certain original sound OS1 in the original sound signal OS is a unit intensity of "1", the original sound signal OS is compressed at a specified compression rate, and after the compression, it is amplified at a specified amplification factor to obtain the original sound OS1. The sound intensity is adjusted to m times the unit intensity "1" which is the original sound intensity. That is, the embedding strength α1 of the standard embedding information SC1 is adjusted to m times. Here, the embedded strength m · α1 satisfies m · α1 <m from the condition that the sound intensity of the echo is smaller than the sound intensity “1” of the original sound OS1. Then, assuming that the ratio of the sound intensity of the original sound OS1 to the embedded intensity is constant, a certain ratio satisfying the condition of 0 <α1 <1 is satisfied. In particular, in the echo diffusion method, for example, α1 is set to a ratio satisfying 0.1 <α1 <0.5.

The process in which the computer embeds the embedded information SC in the original sound signal OS to generate the acoustic signal Sa corresponds to the embedding step. Further, the process in which the computer emits the acoustic signal AS from the speaker 12 corresponds to an example of the sound emission processing step. Further, the process in which the computer extracts the embedded information SC from the acoustic signal Sas collected by the microphone 31 corresponds to an example of the extraction step. Further, the process of causing the computer to output the provided information corresponding to the embedded information SC extracted in the extraction step to the output unit corresponds to an example of the control step. The process of outputting the compressed information CDk in the embedded information SCk extracted by the sound receiving device 30 corresponds to an example of the output step. Further, the process in which the computer compresses the original sound signal OS before the embedded information SC is embedded corresponds to an example of the compression step.

Next, the operation of the acoustic communication system 10 will be described with reference to FIGS. 5 and 6.
In the present embodiment, the compression condition is set from the result of emitting the acoustic signal AS from the speaker 12 and performing the pre-measurement of the reception status of the embedded information SC in the assumed reception area. The compression condition is stored in the memory in the acoustic transmission device 20. The first control unit 23 controls the compressor 24 based on the compression condition read from the memory, and compresses the original sound signal OS under a predetermined compression condition. For example, the threshold value SH is set to a constant value, and the portion of the original sound signal OS that exceeds the threshold value SH is compressed at a specified compression rate β. The first control unit 23 controls the amplifier 25 to amplify the compressed original sound signal OS at a specified amplification factor.

FIG. 5 is a graph illustrating a process of compressing and amplifying the original sound signal OS. FIG. 5A shows an original sound signal OS such as an announcement voice. The compressor 24 compresses the original sound signal OS under the conditions of the threshold value SH and the compression rate β. The three original sounds included in the original sound signal OS shown in FIG. 5A exceed the threshold value SH. The compressor 24 compresses at a specified compression rate, for example, a compression rate β = 0.3. Then, as shown in FIG. 5B, the compressor 24 compresses the portion of the original sound exceeding the threshold value SH that exceeds the threshold value SH at the specified compression rate β, and is shown in FIG. 5B. The compressed original sound signal OS is obtained. The portion of the original sound OS1 that exceeds the threshold value is compressed to become the compressed original sound OSc. Further, when the amplifier 25 amplifies the compressed original sound signal OS shown in FIG. 5B at a specified amplification factor, the amplified original sound signal OSa shown in FIG. 5C is obtained. That is, the amplification by the amplifier 25 amplifies the entire waveform of the compressed original sound signal OS shown in FIG. 5 (b).

The amplified original sound signal OSa has almost the same maximum sound intensity as the original original sound signal OS shown in FIG. 5A, and the original sound having a threshold value SH or less is only amplified without being compressed. As a result, a waveform with a large sound intensity is obtained.

6 (a) and 6 (b) show an acoustic signal AS in which the embedded information SC is embedded in the original sound signal OS. FIG. 6A shows an acoustic signal AS in which the embedded information SC is embedded in the original sound signal OS (FIG. 5A) without compression / amplification. FIG. 6B shows an acoustic signal AS in which the embedded information SC is embedded in the compressed / amplified original sound signal OSa (FIG. 5 (c)).

The embedded information SC is embedded with an embedded strength at a constant ratio of the sound intensity to the original sound in the original sound signal OS, OSa. In FIG. 6A, since the embedded information SC embedded in the original sound having a small sound intensity has a small embedded intensity, reception fails on the receiving side even if the sound is emitted. Since the embedded information SC embedded in the original sound indicated by the mark × in the graph of the figure has a small embedded strength, reception fails.

On the other hand, in the acoustic signal AS shown in FIG. 6B, the sound intensity of the original sound included in the original sound signal OSa is relatively high. Therefore, the embedding strength of the embedding information SC embedded with the embedding strength of a constant ratio of the sound intensity to each original sound becomes relatively large. Therefore, when this acoustic signal AS is emitted, the receiving side succeeds in receiving the embedded information SC. Even in the original sound that fails to receive the embedded information SC indicated by the mark × in the graph of FIG. 5A, the sound intensity of the original sound is enhanced by the compression / amplification processing. Therefore, the embedded information SC can be embedded with a large sound intensity with respect to the original sound. As a result, the receiving side succeeds in receiving the embedded information SC.

The identification information ID is embedded in the original sound signal OS compressed at an appropriate compression rate βp with a predetermined sound intensity αp (embedding intensity). That is, the embedded information SC in which the identification information ID input from the second input unit 22 is encoded by the encoding unit 27 with respect to the compressed / amplified original sound signal OS has a predetermined sound intensity by the embedded unit 28. It is embedded with αp. Since this predetermined sound intensity αp is a value of a constant ratio of the sound intensity of the compressed / amplified original sound, it is a value larger than the sound intensity which is a value of a constant ratio of the sound intensity of the original sound before being compressed / amplified. Become.

The acoustic signal AS in which the embedded information SC is embedded is emitted from the speaker 12 and picked up by the microphone 31 of the information terminal 15 carried by the user who is moving in the assumed reception area. As a result, in the acoustic receiving device 30 in the information terminal 15, reception omission of the embedded information SC extracted by the extraction unit 33 from the acoustic signal Sas from the microphone 31 is suppressed, and the frequency with which the embedded information SC can be reliably received. Will increase.

In the information terminal 15, the second control unit 32 refers to the reference table 36 stored in the memory 35 based on the received identification information ID, and acquires the provided information corresponding to the identification information ID. The second control unit 32 displays the acquired provided information on the display unit 17 via the display processing unit 37, or headphone or earphone connected to the earphone jack of the information terminal 15, or a speaker (all not shown). Sound is emitted from.

For example, on the display unit 17 of the information terminal 15, any one of store information, product information, coupon information, maps, explanations of exhibits, translations of announcements, etc. related to the announcement of the original sound signal OS may be displayed. Multiple are displayed. Further, from the headphones, earphones or speakers connected to the information terminal 15, any one of store information, product information, coupon information, route guidance voice, translation voice of the announcement, etc. related to the announcement of the original sound signal OS or the like. Multiple sounds are emitted. For example, when the original sound signal OS is music such as BMG, and the assumed reception area where the user carrying the information terminal 15 is moving is a shopping district or a department store, the store information, product information, coupon information, map, road One or more of the guidance voices are displayed or emitted on the information terminal 15. When the original sound signal OS is music such as BMG, the assumed reception area RA where the user carrying the information terminal 15 is located is in a museum, a museum, a station yard, a stadium, a conference hall, or the like. In the case of a venue, one or a plurality of explanatory texts, multilingual explanatory voices, guidance texts, multilingual guidance voices, and the like are displayed or emitted on the information terminal 15.

In this way, the identification information ID can be embedded in the original sound signal OS such as announcements and music with an appropriate embedding strength in consideration of the reception environment of the assumed reception area, so that the information terminal 15 does not receive the identification information ID. Is unlikely to occur. Therefore, it is possible to suppress a provision error in which the provision information corresponding to the identification information ID is not displayed or emitted on the information terminal 15.

As described in detail above, according to the first embodiment, the following effects can be obtained.
(1) The acoustic communication system 10 includes an acoustic transmission device 20 having a speaker 12 for emitting an acoustic signal AS in which embedded information SC is embedded, and an acoustic receiving device 30 having a microphone 31 for collecting the acoustic signal AS. To prepare for. The acoustic transmission device 20 includes an embedded unit 28 that embeds an embedded information SC in the original sound signal OS to generate an acoustic signal AS, a sound emitting processing unit 29 that emits an acoustic signal AS from a speaker 12, and an embedded information SC. It is provided with a compressor 24 that compresses the original sound signal OS before the embedding. Further, the acoustic receiving device 30 is extracted by an extraction unit 33 that extracts the embedded information SC from the acoustic signal AS picked up by the microphone 31, a display unit 17 as an example of an output unit that outputs information, and an extraction unit 33. A second control unit 32 for outputting the provided information corresponding to the embedded information SC to the display unit 17 is provided.

According to this configuration, since the original sound signal OS before the embedded information SC is embedded is compressed by the compressor 24, the sound intensity (volume) of the acoustic signal AS can be increased without being noisy and without cracking. Therefore, since the sound intensity (embedded strength) of the embedded information SC embedded in the acoustic signal AS is also increased, it is possible to suppress reception omission of the embedded information SC in the acoustic receiving device 30.

(2) The sound transmission device 20 includes an amplifier 25 that amplifies the original sound signal OS compressed by the compressor 24. According to this configuration, the original sound signal OS before the embedded information SC is embedded is compressed by the compressor 24. Further, the compressed original sound signal OS is amplified by the amplifier 25. Therefore, the sound intensity (volume) of the acoustic signal AS is increased by amplification without being noisy and without cracking. Therefore, since the sound intensity of the embedded information SC embedded in the acoustic signal AS is also increased, it is possible to suppress reception omission of the embedded information SC in the acoustic receiving device 30.

(3) The compressor 24 compresses the portion of the original sound signal OS exceeding the threshold value SH at a predetermined compression rate β, and does not compress the portion below the threshold value SH. According to this configuration, when the sound intensity (volume) of the acoustic signal AS is increased, the sound intensity (amplitude) of the original sound having the maximum amplitude is not noisy and does not crack, and the sound intensity (amplitude) of the original sound below the threshold SH is increased. Can be done. Therefore, the sound intensity (embedded strength) of the embedded information SC that is hidden and embedded in the original sound is increased, and reception omission of the embedded information SC can be suppressed.

(4) The compressor 24 adjusts at least one of the threshold value SH and the compression rate β. According to this configuration, it is possible to selectively increase the sound intensity of a small original sound that is not desired to be compressed among the original sound signal OS. For example, by adjusting the threshold value SH, it is possible to select a portion that is desired to be compressed and a portion that is not desired to be compressed. Further, by adjusting the compression rate β, the compression rate β of the portion of the original sound signal OS that exceeds the threshold value SH of the original sound to be compressed can be adjusted, so that the small original sound of the threshold value SH or less can be suppressed while suppressing the deterioration of the sound quality due to compression. The sound quality of can be increased.

(5) The threshold value SH is set to a value larger than the embedding strength when the embedding unit 28 embeds the embedding information SC. That is, the threshold value SH is set to a value larger than the assumed maximum embedding strength of the embedding information SC. According to this configuration, the smaller original sound among the original sounds to which the embedded information SC is embedded is not compressed. Therefore, when the acoustic signal AS is emitted at an appropriate volume, the sound intensity of the smaller original sound can be effectively increased as compared with that before compression, and the sound intensity of the embedded information SC embedded in the original sound is increased accordingly. Can be increased. Therefore, it is possible to suppress reception omission of the embedded information SC in the sound receiving device 30.

(6) The embedded unit 28 has a function of detecting an original sound having an amplitude equal to or larger than a set value among the input original sound signal OS. The embedding unit 28 masks the detected original sound and embeds the embedding information SC. According to this configuration, since the embedded information SC is embedded in a relatively large original sound having a sound intensity equal to or higher than the set value, the sound intensity of the embedded information SC is increased. As a result, it is possible to suppress reception omission of the embedded information SC in the sound receiving device 30.

(7) The acoustic transmission device 20 includes an encoding unit 27 that encodes information including the compressed information CD into the embedded information SC. The embedding unit 28 embeds the embedding information SC in the original sound signal OS. The acoustic transmission device 20 includes a decoding unit 34 for decoding the embedded information SC extracted from the acoustic signal AS by the extraction unit 33 into information including a compressed information CD. According to this configuration, since the embedded information SC is embedded in the original sound signal OS by a diffusion method, it is possible to suppress the adverse effect of the embedded information SC on the hearing of the original sound as much as possible.

(8) The acoustic transmission device 20 includes an embedded unit 28 that embeds the embedded information SC in the original sound signal OS to generate an acoustic signal Sas, and a sound emitting processing unit 29 that emits an acoustic signal AS from the speaker 12. It includes a compressor 24 that compresses the original sound signal OS before the embedded information SC is embedded. According to this configuration, the same operation and effect as the acoustic transmission device 20 constituting the acoustic communication system 10 can be obtained.

(9) The acoustic receiving device 30 includes a microphone 31 that collects an acoustic signal AS, an extraction unit 33 that extracts embedded information SC from the acoustic signal AS collected by the microphone 31, and an embedding unit 33 extracted by the extraction unit 33. A determination unit 38 for determining whether the information included in the information SC is identification information or a compressed information CD, and a second control unit 32 are provided. When the determination result of the determination unit 38 is the compressed information CD, the second control unit 32 outputs the received compressed information CD to the first output unit, and when the determination result of the determination unit 38 is the identification information ID. Outputs the provided information corresponding to the identification information ID to the second output unit. In the present embodiment, the first output unit is a display unit 17 or a transmission unit 39 and an antenna 16, and displays a compressed information CD or outputs the compressed information CD by wireless communication. The second output unit is a display unit 17, an earphone jack, or a speaker, and displays or emits the provided information corresponding to the identification information ID. According to this configuration, the same operation and effect as the acoustic receiving device 30 constituting the acoustic communication system 10 can be obtained.

(10) The program to be executed by the computer included in the acoustic transmission device 20 in the acoustic communication system 10 causes the computer to function as an embedded unit 28, a sound emission processing unit 29, a compressor 24, and an amplifier 25. The embedding unit 28 embeds the embedding information SC in the original sound signal OS to generate an acoustic signal AS. The sound emission processing unit 29 emits the acoustic signal AS from the speaker 12. The compressor 24 compresses the original sound signal OS before the embedded information SC is embedded. The amplifier 25 amplifies the compressed original sound signal OS before being emitted from the speaker 12. Therefore, by causing the computer to execute the program, the same effect as that of the sound transmission device 20 can be obtained.

(11) The program to be executed by the computer included in the sound receiving device 30 in the sound communication system 10 causes the computer to function as the extraction unit 33, the determination unit 38, and the second control unit 32. The extraction unit 33 extracts the embedded information SC from the acoustic signal AS picked up by the microphone 31. The determination unit 38 determines whether the information contained in the embedded information SC extracted by the extraction unit 33 is identification information or compressed information CD. When the determination result of the determination unit 38 is the compressed information CD, the second control unit 32 outputs the received compressed information CD to the first output unit, and when the determination result of the determination unit 38 is the identification information ID. Outputs the provided information corresponding to the identification information ID to the second output unit. Therefore, by causing the computer to execute the program, the same effect as that of the sound receiving device 30 can be obtained.

(12) The sound transmitting device 20 receives the sound signal AS transmitted by the sound transmitting device 20 by emitting the sound signal AS in which the embedded information SC is embedded from the speaker 12, and the sound receiving device 30 picking up the sound by the microphone 31. The acoustic signal transmission method to be performed includes an embedding step, a sound emitting step, an extraction step, a control step, and a compression step. In the embedding step, the acoustic transmission device 20 embeds the embedding information SC in the original sound signal OS to generate an acoustic signal AS. In the sound emitting step in which the sound transmitting device 20 emits the sound signal AS from the speaker 12, and in the extraction step, the sound receiving device 30 extracts the embedded information SC from the sound signal AS picked up by the microphone 31. In the control step, the sound receiving device 30 causes the display unit 17 to output the provided information corresponding to the embedded information SC extracted in the extraction step. In the compression step, the acoustic transmission device 20 compresses the original sound signal OS before the embedded information SC is embedded. According to this acoustic signal transmission method, the same effect as that of the acoustic communication system 10 can be obtained.

(Second Embodiment)
Next, the second embodiment will be described with reference to FIGS. 9 to 13. The acoustic communication system 10 of the second embodiment adjusts the compression conditions in real time. The basic configuration of the sound transmitting device 20 and the sound receiving device 30 is the same as that of the first embodiment. The sound transmission device 20 includes a measurement mode as an example of a test mode for measuring compression conditions in real time. The sound receiving device 30 determines whether or not it is in the measurement mode, and performs communication for responding to the sound transmitting device 20 with the determination result. Therefore, the sound transmitting device 20 has a communication function, and the sound receiving device 30 further has a determination function and a communication function.

As shown in FIG. 9, the acoustic transmission device 20 emits an acoustic signal AS in which embedded information SC1, SC2, ..., SCn are embedded in a plurality of original sound signal OSs having different compression conditions from the speaker 12. The information terminal 15 carried by the user in the assumed reception area RA collects the acoustic signal AS by the microphone 31.

The acoustic signal AS is composed of an original sound signal OS composed of voice or music, and a plurality of embedded information SC1, SC2, ... SCn embedded in the original sound signal OS at predetermined time intervals. These embedded information SCk (where k is k = 1, 2, ..., N) are compression information related to the compression conditions of the original sound signal OS in the measurement mode. Since the embedded information SCk is hidden by the sound digital watermarking technology, the embedded information SC is embedded with a sound intensity smaller than the sound intensity of the original sound so as to be hidden by the original sound such as the announcement voice in the acoustic signal AS. By changing the compression conditions of the original sound signal OS, the sound intensity of the embedded information SC embedded in the original sounds having different compression rates is different when the acoustic signal AS is emitted at a predetermined volume.

The sound receiving device 30 built in the information terminal 15 cannot receive the embedded information SCk-1 whose sound intensity is too low, and can receive the embedded information SCk, ..., SCn having the lowest sound intensity or higher. The sound receiving device 30 wirelessly transmits the compressed information CDk, which is the minimum compression condition included in the embedded information SC received from the antenna 16 of the information terminal 15. The transmitted compressed information CDk is received by the antenna 13 of the acoustic transmission device 20 via wireless communication, the Internet IN, or a public wireless communication network. The sound transmission device 20 determines an appropriate compression condition based on the received compression information CDk. After that, the acoustic transmission device 20 compresses the original sound signal OS under the determined appropriate compression conditions, amplifies the compressed original sound signal OS, and then embeds the identification information ID in the amplified original sound signal OSa to obtain the acoustic signal Sas. Generate. Therefore, in the normal mode, the acoustic transmission device 20 transmits the embedded information SC to the acoustic receiving device 30 by emitting the acoustic signal AS in which the identification information ID is embedded as the embedded information SC.

Here, whether or not the information terminal 15 in the assumed reception area RA can receive the acoustic signal AS depends on the distance from the speaker 12 to the inside of the assumed reception area RA, the noise environment in the assumed reception area RA, and the like. Therefore, in determining the compression conditions applied to the compression of the original sound signal OS, the reception status is tested by the information terminal 15 in the assumed reception area RA. As described above, the acoustic transmission device 20 of the present embodiment includes a measurement mode as a test mode for collecting necessary measurement information from the information terminal 15 in the assumed reception area RA in order to determine an appropriate compression condition.

When the information terminal 15 is on the broadcasting subject side, the information terminal 15 is installed in the assumed reception area RA. Alternatively, a worker on the broadcasting subject side carries an information terminal 15 to measure the reception status of the embedded information SC and moves within the assumed reception area RA. Further, the information terminal 15 may be a portable information terminal 15 such as a smartphone carried by a user moving in the assumed reception area RA.

The operator on the broadcasting subject side carrying the information terminal 15 receives the embedded information SC1, SC2, ..., SCn by collecting the acoustic signal AS by the information terminal 15 in the assumed reception area RA. Then, the acoustic receiving device 30 is compressed information indicating the compression conditions included in the received embedded information SCk among the plurality of embedded information SC1, SC2, ..., SCn embedded in the acoustic signal AS having different compression rates βk. Output CDk. The output of the compressed information CDk is a display on the display unit 17 (see FIG. 10) of the information terminal 15 or a transmission from the information terminal 15 via wireless communication via the antenna 16.

Further, the configuration of the acoustic communication system 10 shown in FIG. 11 can be used. In the acoustic communication system 10, the acoustic transmission device 20 adjusts the compression rate in real time, and the information terminal 15 can receive the compressed information CDk and the GPS receiver built in the information terminal 15 to determine the appropriate compression rate. The position information (GPS position information) received by 18 is used.

As shown in FIG. 11, the speaker 12 of the acoustic transmission device 20 emits an acoustic signal AS in which a plurality of embedded information SC1, SC2, ..., SCn having different compression rates are embedded. The acoustic signal AS is picked up by the microphones 31 of the plurality of information terminals 15. Each information terminal 15 transmits the received compressed information CDk and the position information received by the GPS receiver 18 from the antenna 16 by wireless communication, respectively. The acoustic transmission device 20 receives the plurality of sets of compressed information CDk and position information transmitted by wireless communication from each information terminal 15 by the antenna 13. For example, a plurality of sets of compressed information CDk and position information transmitted from the antennas 16 of the plurality of information terminals 15 are received by the antenna 13 of the acoustic transmission device 20 via the Internet IN or the public wireless communication network. The acoustic transmission device 20 may download a plurality of sets of compressed information CDk and position information transmitted from the plurality of information terminals 15 from the server. The sound transmission device 20 determines an appropriate compression condition based on the received compression information CDk and position information. The first control unit 23 shown in FIG. 12 compresses the original sound signal OS at a determined appropriate compression rate.

Next, the configuration of the sound transmitting device 20 and the sound receiving device 30 will be described with reference to FIG. 12. The description of the configuration common to the first embodiment will be omitted. First, the sound transmission device 20 will be described. The sound transmission device 20 includes a first input unit 21 for inputting the original sound signal OS and a second input unit 22 for inputting the identification information ID. The sound transmission device 20 includes a first control unit 23 that collectively controls the sound transmission device 20.

As shown in FIG. 12, the first control unit 23 switches between the measurement mode and the normal mode. The first control unit 23 switches to the measurement mode periodically or irregularly between the normal modes. In the measurement mode, a measurement test is performed to measure the compression conditions. The first control unit 23 sends the compression information CD to the encoding unit 27 in the measurement mode. A plurality of types of compressed information CDs having different compression conditions are stored in the memory. A plurality of compression information CD1, CD2, ..., CDn having different compression conditions are stored in the memory. When the measurement mode is set, the first control unit 23 sends a plurality of compressed information CD1, CD2, ..., CDn read from the memory to the encoding unit 27. Further, the first control unit 23 outputs the identification information ID to the encoding unit 27 in the normal mode.

Further, the acoustic transmission device 20 includes a compressor 24 that compresses the original sound signal OS and an amplifier 25 that amplifies the compressed original sound signal OS. Further, the acoustic transmission device 20 includes a diffusion code generator 26, an encoding unit 27, and an embedded unit 28 having a function of convolving the embedded information SC in the original sound signal OS. Further, the acoustic transmission device 20 is compressed information received by the sound emission processing unit 29 and the antenna 13 that emit the acoustic signal AS from the speaker 12 based on the acoustic signal Sa in which the embedded information SC by the embedded unit 28 is embedded. A receiving unit 20B for receiving a CDk is provided.

The first control unit 23 adjusts the compression conditions for compressing the original sound signal OS by the compressor 24. The compression condition is shown in the example of the compression rate β, but it may be at least one of the compression rate β and the threshold value SH. Further, the first control unit 23 adjusts the amplification factor for amplifying the compressed original sound signal OS to the amplifier 25. The encoding unit 27 encodes (encodes) the identification information ID into the embedded information SC when the acoustic transmission device 20 is in the normal mode. Further, the encoding unit 27 encodes (encodes) the compressed information CD sent from the first control unit 23 into the embedded information SC when the acoustic transmission device 20 is in the measurement mode. The first control unit 23 instructs the embedding unit 28 to set a value. The embedded unit 28 has a function of detecting an original sound having an amplitude of a set value or more among a plurality of original sounds in the original sound signal OS. Then, the embedded unit 28 embeds the compressed information CD or the embedded information SC in which the identification information ID is encoded by the encoding unit 27 in the detected original sound.

The acoustic transmission device 20 of the present embodiment has the same embedded information even if there is a reception omission of the embedded information SC on the acoustic receiving device 30 side due to sound interruption, undersound, noise, etc. of the acoustic signal AS. By repeatedly transmitting the SC a plurality of times, reception omission is suppressed. Further, a plurality of embedded information SC1, SC2, ..., SCn may be sent once in order and repeated a plurality of times.

The receiving unit 20B receives the compressed information CDk transmitted by wireless communication from the antenna 16 of the information terminal 15 via the antenna 13. The communication between the antennas 13 and 16 is transmitted via a communication network such as the Internet IN shown in FIG. The compressed information CDk received by the receiving unit 20B is input to the first control unit 23. The first control unit 23 determines an appropriate compression rate βp based on the compression information CDk input from the reception unit 20B. The first control unit 23 controls the compressor 24 based on the determined appropriate compression rate βp, and compresses the original sound signal OS at an appropriate compression rate βp. The original sound signal OS compressed at an appropriate compression rate βp is amplified by the amplifier 25 and then input to the embedding unit 28.

The sound emission processing unit 29 emits an acoustic signal AS from the speaker 12 based on the acoustic signal Sas generated by the embedded unit 28. In the measurement mode, the speaker 12 emits an acoustic signal AS in which embedded information SC1, SC2, ..., SCn having different compression rates are embedded, and in the normal mode, the identification information ID is embedded as the embedded information SC. The acoustic signal AS is emitted.

The receiving unit 20B receives the compressed information CDk, which will be described later, transmitted by wireless communication from the antenna 16 on the acoustic receiving device 30 side via the antenna 13. The receiving unit 20B outputs the received compressed information CDk to the first control unit 23. Further, the first control unit 23 may input the compression information CDk from the input operation unit 14. The first control unit 23 determines an appropriate compression condition based on the input compression information CDk.

In addition to the case where the compression rate β is used, the compression condition may be a combination of the compression rate β and the threshold value SH when the threshold value SH is used. Further, the compression information CD1, CD2, ..., CDn transmitted in the measurement mode is not limited to the compression rate β, and may be a combination of the compression rate β and the threshold value SH when the threshold value SH is used. Therefore, the value of the compression level becomes larger as the degree of compression is larger. The larger the value of the compression level, the smaller the compression rate β and the smaller the threshold SH.

The acoustic receiving device 30 shown in FIG. 12 includes an extraction unit 33 and a decoding unit 34 that extract the embedded information SC from the acoustic signal Sas input from the receiving circuit. The extraction unit 33 and the decoding unit 34 have the same functions as those in the first embodiment. The extraction unit 33 extracts the embedded information SC1, SC2, ..., SCn from the acoustic signal Sas in the measurement mode. These embedded information SC1, SC2, ..., SCn are compressed information CD1, CD2, ..., CDn encoded. Further, the extraction unit 33 extracts the embedded information SC from the acoustic signal Sas in the normal mode. The embedded information SC is a coded identification information ID. In this embodiment, the extraction unit 33 and the decoding unit 34 constitute an example of the extraction unit.

The extraction unit 33 extracts the embedded information SC from the acoustic signal Sas by a method corresponding to the diffusion method of the sound digital watermarking method. The decoding unit 34 decodes the embedded information SC. The decoding unit 34 decodes the embedded information SC into the compressed information CD in the measurement mode. Further, the decoding unit 34 decodes the embedded information SC into the identification information ID in the normal mode.

Further, the acoustic receiving device 30 uses an antenna 16 for a determination unit 38 that determines whether the decoding result of the decoding unit 34 is the compressed information CDk or the identification information ID, and the compressed information CDk that is the determination result of the determination unit 38. A transmission unit 39 for transmitting via wireless communication and a display processing unit 37 for displaying the compressed information CDk on the display unit 17 are provided.

The determination unit 38 determines whether the information input from the decoding unit 34 is a compressed information CD or an identification information ID. If the result of the determination is an identification information ID, the identification information ID is sent to the second control unit 32. If the result of the determination is the compressed information CDk, the determination unit 38 sends the compressed information CDk to the transmission unit 39 and the display processing unit 37.

The transmission unit 39 transmits the compressed information CDk input from the determination unit 38 by wireless communication via a transmission / reception circuit (not shown) included in the information terminal 15 and an antenna 16. The transmission unit 39 transmits the compressed information CDk by designating the sound transmission device 20 or the server as the destination.

As shown in FIG. 12, the sound receiving device 30 is provided in a portable information terminal 15 having an antenna 16 and a transmitting unit 39 as an example of an output unit. The transmission unit 39 outputs the compressed information CD by wireless communication. Further, the acoustic transmission device 20 includes an antenna 13. The sound transmission device 20 and the information terminal 15 can wirelessly communicate with each other via the antennas 13 and 16. This wireless communication is performed between the antennas 13 and 16 via the Internet IN or a public communication network. The sound transmission device 20 can be connected to the Internet IN by wireless communication via the antenna 13. Further, the information terminal 15 can be connected to the Internet IN by wireless communication via the antenna 16. A server is connected to the Internet IN. The compressed information CD output by the sound receiving device 30 by wireless communication is transmitted to a server on the Internet IN. The server is owned by the provider or broadcaster. The sound transmission device 20 may download the compressed information CD output and registered by the information terminal 15 from the server. The wireless communication may be performed directly between the antennas 13 and 16.

Further, the sound receiving device 30 is provided in a portable information terminal 15 having a display unit 17 shown in FIG. 10 as an example of an output unit. As shown in FIG. 10, the sound receiving device 30 causes the display unit 17 to display the compressed information CD included in the received embedded information SCk.

The different compression rates β included in the embedded information SC1, SC2, ..., SCn are set in n steps. That is, the compression levels 1 to n are set as the compression information CD. The number of adjustment stages of the compression rate β may be any of two stages, three stages, six stages, and nine stages. In this example, the example in which the number of stages of the compression rate β is set to 6 stages (n = 6) of the compression levels 1 to 6 will be described. In the measurement test, for example, when the sound receiving device 30 can receive the embedded information SC having the compression level 4 or higher, the embedded information SC having the compression level 4 to 7 can be received. In this case, the acoustic receiving device 30 cannot receive the embedded information SC of the compression levels 1 to 3.

FIG. 10 shows an example of the measurement result of the measurement test displayed on the display unit 17 of the information terminal 15 in the measurement mode. In the example shown in FIG. 10, the display unit 17 of the information terminal 15 displays the compressed information CDk indicating the lowest compression condition among the received compressed information CDk, ..., And CDn in the embedded information SCk. In the example in which the embedded information SC having the compression level 4 or higher can be received, as shown in FIG. 10, the “compression information” is, for example, the lowest level “compression level: 4” among the received compression levels 4 to 5. Is displayed. The value of this compression level indicates a relative value. The higher the degree of compression, the higher the value of the compression level.

The compression levels 1 to 3 below the minimum compression level 4 correspond to the case where the degree of compression is too small. Further, the lowest compression level 4 or the compression level 5 which is one step larger than the compression level 4 corresponds to the appropriate compression rate. Further, the compression level 6 which is two or more steps larger than the minimum compression level 4 corresponds to the case where the degree of compression is too large. The acoustic transmission device 20 of the present embodiment has a compression rate βk having the lowest compression rate among the compression information CDk, ..., CDn received in the measurement test, or a compression rate one step higher than the lowest compression rate. Set βk + 1.

The sound transmitting device 20 of the present embodiment acquires the value of the compression level displayed on the display unit 17 by the sound receiving device 30 or the value of the compression level included in the response signal transmitted by wireless communication. For example, the operator operates the input operation unit 14 to input the value of the compression level displayed on the display unit 17 to the sound transmission device 20. The first control unit 23 in the acoustic transmission device 20 has a compression rate βk corresponding to the lowest compression level that can be received or a compression rate βk + 1 one step higher than that, based on the value of the input or received compression level. Adjust to. In the example where the lowest compression level shown in FIG. 10 is "4", the acoustic transmitter 20 has a compression rate corresponding to the compression level "4" or a compression corresponding to a compression level "5" one step higher than this. Set the rate. In the example shown in FIG. 2, the compression level 4 corresponds to the compression rate β = 0.4, and the compression level 5 corresponds to the compression rate β = 0.2.

As described above, in the acoustic communication system 10, the acoustic transmission device 20 sets an appropriate compression rate βp for compressing the original sound signal OS according to the measurement result of the measurement test. Then, the acoustic transmission device 20 compresses the original sound signal OS at an appropriate compression rate βp, so that the volume of the acoustic signal AS generated by embedding the embedded information SC in the compressed original sound signal OS is within an appropriate range. Raise with. As a result, the embedding strength of the embedded information SC is adjusted so that the information terminal 15 located in the assumed reception area RA can reliably receive the information. In this example, the function of the amplifier 25 to amplify the compressed original sound signal OS corresponds to a part of the function of raising the volume of the acoustic signal AS. In a configuration in which the sound transmitting device 20 or the broadcasting device 11 includes a volume adjusting operation unit and a volume adjusting unit for adjusting the volume of the sound signal AS, the amplifier 25 may not be provided.

The program stored in the memory in the acoustic transmitter 20 shown in FIG. 12 releases the computer to the first control unit 23, the compressor 24, the amplifier 25, the diffusion code generator 26, the encoding unit 27, the embedded unit 28, and the release unit. It functions as a sound processing unit 29 and a receiving unit 20B. The parts 20B, 23 to 29 are not limited to software, and may be configured by software and hardware, or may be configured by hardware.

Further, the program stored in the memory 35 (see FIG. 4) in the sound receiving device 30 causes the computer to function as each unit 32 to 34, 37 to 39. Specifically, the program stored in the memory 35 in the sound receiving device 30 causes the computer to function as a second control unit 32, an extraction unit 33, a decoding unit 34, a determination unit 38, a transmission unit 39, and a display processing unit 37. .. Note that each unit 32 to 34, 37 to 39 is not limited to software, and may be configured by software and hardware, or may be configured by hardware.

Further, the sound transmission device 20 shown in FIG. 12 stores a program on the sound transmission device side shown on the left side in FIG. 13 in a memory. Further, the information terminal 15 having a built-in sound receiving device 30 shown in FIG. 12 stores a program on the information terminal 15 side shown on the right side in FIG. 13 in a memory.

Hereinafter, the operation of the acoustic communication system 10 in the second embodiment will be described with reference to FIG. In the following, an example in which the compression condition is the compression rate β will be described. The sound transmission device 20 shifts from the normal mode to the measurement mode periodically or irregularly.

First, in step S11, the first control unit 23 of the acoustic transmission device 20 controls the compressor to compress the original sound signal OS at different compression rates. For example, the original sound signal OS is compressed with six different compression rates β = 0, 0.2, 0.4, 0.6, 0.8, 1.0.

In the next step S12, the first control unit 23 controls the amplifier 25 to amplify the original sound signal OS at a specified amplification factor.
In step S13, the first control unit 23 embeds the embedded information SC1, SC2, ..., SCn for testing indicating the compression rate in the original sound signal OS. That is, the first control unit 23 encodes the compressed information CD1, CD2, ..., CDn into the embedded information SC1, SC2, ..., SCn by the encoding unit 27, and the encoded information SC1, SC2, ..., SCn is embedded in the original sound signal OS compressed at each compression rate β.

In the next step S14, the first control unit 23 transmits the acoustic signal AS. That is, in the first control unit 23, the embedded information SC1, SC2, ..., SCn in which the compressed information CD1, CD2, ..., CDn are encoded are embedded in the original sound signal OS compressed at different compression rates. The acoustic signal AS generated in 1 is transmitted (sounded) from the speaker 12. This acoustic signal AS is picked up by the microphone 31 of the information terminal 15.

In step S21 shown in FIG. 13, the second control unit 32 of the information terminal 15 determines whether or not the embedded information SC has been received. Specifically, the second control unit 32 determines whether or not the embedded information SCk extracted by the extraction unit 33 can be received from the acoustic signal Sas from the microphone 31. The embedded information SCk includes the compressed information CDk and a value indicating the test. Assuming that the embedded information SC is, for example, 8 bits, 3 bits are used for the compressed information CDk, and 1 bit is used for determining whether it is a test or not. In the sound receiving device 30, the extraction unit 33 extracts the embedded information SCk. The embedded information SCk is decoded by the decoding unit 34, and the compressed information CDk and the value indicating the test are taken out.

In step S22, the second control unit 32 determines whether or not the test is performed. Specifically, if the embedded information SCk has a value indicating the test, it is determined to be a test, and if it is not a value indicating the test, it is determined not to be a test. This determination may be performed by the second control unit 32 by the determination unit 38. The second control unit 32 proceeds to step S23 if it is a test, and proceeds to step S25 if it is not a test. In the measurement mode, the embedded information SC1, SC2, ..., SCn include values indicating the test, so that the test is determined.

In step S23, the second control unit 32 acquires the compression information CDk from the embedded information SCk. In this example, the second control unit 32 causes the determination unit 38 to determine whether the embedded information SC is the compressed information CD or the identification information ID, and acquires the determination result.

In the next step S24, the second control unit 32 transmits a response signal including the compressed information CDk by wireless communication. In this example, when the determination result of the determination unit 38 is the compression information CDk, the second control unit 32 transmits the lowest compression information CDk among the compression information CDk, ..., CDn received by the determination unit 38 to the acoustic transmission device 20. Give instructions to send to. As a result, the determination unit 38 instructs the transmission unit 39 to transmit the lowest compressed information CDk among the received compressed information CDk, ..., CDn. The transmission unit 39 transmits the indicated minimum compressed information CDk from the antenna 16 by wireless communication. The transmitted minimum compressed information CDk is transmitted to the acoustic transmission device 20 via the Internet IN or a public wireless communication network. When the worker of the broadcasting company uses it for measuring the reception status, the second control unit 32 causes the display unit 17 to display the compressed information CDk as shown in FIG.

In the example of the acoustic communication system 10 shown in FIG. 11, in step S24, the second control unit 32 of the information terminal 15 has received the compressed information CDk and the current position of the information terminal 15 received by the GPS receiver 18. The position information indicating the above is transmitted from the antenna 16 by wireless communication, respectively. When the worker of the broadcasting company uses it for measuring the reception status, the second control unit 32 causes the display unit 17 to display the compressed information CDk and the position information. In this way, in the sound receiving device 30, the first output unit is configured by the display unit 17, the transmission unit 39, and the antenna 16 that output the compressed information CD or the combination of the compressed information CD and the position information.

Meanwhile, in step S15, the first control unit 23 of the acoustic transmission device 20 determines whether or not the response signal has been received. Then, when the acoustic transmission device 20 receives the response signal including the compressed information CDk transmitted by wireless communication from the antenna 16 of the information terminal 15 by the antenna 13, the first control unit 23 proceeds to step S16.

In step S16, the first control unit 23 of the acoustic transmission device 20 compresses the original sound signal OS at an appropriate compression rate βp based on the compression information CDk. Specifically, the first control unit 23 determines an appropriate compression rate βp from the lowest compression information CDk received. Further, in the configuration of the acoustic communication system shown in FIG. 11, the first control unit 23 determines an appropriate compression rate βp based on the received compression information CDk and position information. For example, the first control unit 23 selects the compressed information CDk received in combination with the position information indicating the position in the assumed reception area RA, and determines an appropriate compression rate βp based on the selected compression information CDk. By determining the appropriate compression rate βp, the measurement mode ends and the mode shifts to the normal mode. Then, the first control unit 23 instructs the compressor 24 to compress the original sound signal OS at an appropriate compression rate. The compressor 24 compresses the original sound signal OS at an appropriate compression rate βp.

In the next step S17, the first control unit 23 controls the amplifier 25 to amplify the original sound signal OS at a specified amplification factor.
In the next step S18, the first control unit 23 embeds the identification information ID in the original sound signal OS. That is, the first control unit 23 encodes the identification information ID into the embedded information SC by the encoding unit 27, and embeds the encoded embedded information SC in the original sound signal OS compressed at an appropriate compression rate βp. As a result, the acoustic signal Sas is generated.

In the next step S19, the first control unit 23 transmits the acoustic signal AS. That is, the first control unit 23 transmits (sounds) the acoustic signal AS from the speaker 12 via the sound emission processing unit 29 based on the acoustic signal Sas. This acoustic signal AS is picked up by the microphone 31 of the information terminal 15.

Then, in step S22, the determination unit 38 of the information terminal 15 determines that it is not a test because the embedded information SC is the identification information ID. Specifically, in the information terminal 15, the extraction unit 33 extracts the embedded information SC from the acoustic signal Sas from the microphone 31 that collects the acoustic signal AS, and the embedded information SC is decoded by the decoding unit 34. Receives the identification information ID. If the determination unit 38 determines that the identification information ID is not a test because it does not include a value to the effect of the test, the determination unit 38 proceeds to step S25. At this time, the identification information ID is sent from the determination unit 38 to the second control unit 32.

In step S25, the second control unit 32 outputs the provided information corresponding to the identification information ID. Specifically, the second control unit 32 acquires the provided information corresponding to the identification information ID by referring to the reference table 36 (see FIG. 4) based on the identification information ID. Then, the second control unit 32 displays or outputs the provided information by voice. That is, the second control unit 32 displays the provided information on the display unit 17 by the display processing unit 37, or emits the provided information from the headphones, earphones, and speakers by the sound emission processing unit (not shown). The information provided by the information terminal 15 to the user by display or sound emission is the same as that of the first embodiment. In this way, in the sound receiving device 30, the second output unit is configured by the display unit 17, the earphone jack and the speaker (not shown) that output the provided information.

The acoustic communication system 10 of the second embodiment shifts to the measurement mode periodically or irregularly. In this measurement mode, the information terminal 15 in the assumed reception area RA picks up the acoustic signal AS with the microphone 31. The sound transmission device 20 has the lowest degree of compression that the sound reception device 30 can receive among a plurality of compression information CD1, CD2, ..., CDn embedded in the sound signal AS emitted from the speaker 12 and having different compression conditions. Set appropriate compression conditions based on the compression information CDk. As a result, the acoustic transmission device 20 compresses the original sound signal OS under appropriate compression conditions, embeds the identification information ID in the compressed original sound signal OS, and generates the acoustic signal Sas. Therefore, when the acoustic signal AS is raised to a volume within an appropriate range and emitted, reception omission in which the information terminal 15 fails to receive the identification information ID is unlikely to occur. Moreover, since the compression conditions are adjusted to be appropriate in real time in response to changes in the reception environment in the assumed reception area RA at that time, the information terminal 15 fails to receive the identification information ID in the assumed reception area RA. Leakage is less likely to occur.

According to this second embodiment, the effects (1) to (12) of the first embodiment can be obtained in the same manner. In addition, the following effects can be obtained.
(13) In the acoustic communication system 10, it is possible to adjust to an appropriate compression condition in real time. Therefore, it is possible to reduce reception omission in which the sound receiving device 30 built in the information terminal 15 fails to receive the identification information ID. Further, for example, in the case of a configuration in which the same identification information ID is repeatedly transmitted a predetermined number of times in order to reduce reception omission of the identification information ID, the acoustic receiving device 30 receives the identification information ID within the range of the predetermined plurality of transmissions. The frequency with which you can do it will increase significantly.

(14) The acoustic transmission device 20 changes the compression conditions of the compressor 24 and emits an acoustic signal AS in which the embedded information SC including the compression information CD1, CD2, ..., CDn related to each compression condition is embedded as a sound digital watermark. The sound processing unit 29 includes a test mode (measurement mode) in which sound is emitted from the speaker 12. The sound receiving device 30 includes a display unit 17 or a transmission unit 39 and an antenna 16 as an output unit for outputting the compressed information CD included in the embedded information SC extracted by the extraction unit 33. The sound transmission device 20 includes a first control unit 23 that inputs the compression information CD output by the display unit 17 or the transmission unit 39 and the antenna 16 and causes the compressor 24 to compress the original sound signal OS under compression conditions based on the compression information CD. ..

According to this configuration, the sound transmission device 20 can obtain a compressed information CD suitable for reception based on the embedded information SCk that can be received on the sound reception device 30 side in the measurement mode. Therefore, the acoustic transmission device 20 can compress the original sound signal OS under appropriate compression conditions based on the received compression information CD. Therefore, it is possible to suppress reception omission of the embedded information SC in the sound receiving device 30.

(15) The sound receiving device 30 is provided in a portable information terminal 15 having a display unit 17 as an output unit. The display unit 17 displays the compressed information CD. The sound transmission device 20 includes an input operation unit 14 for inputting the compressed information CD displayed by the display unit 17. The first control unit 23 causes the compressor 24 to compress the original sound signal OS under the compression conditions determined based on the input compression information CD. According to this configuration, since the embedded information SC received in the measurement mode is displayed on the display unit 17, the displayed compressed information CD is given to the sound transmission device 20 by the operation of the input operation unit 14. Therefore, the operator can set appropriate compression conditions for the sound transmission device 20 by inputting the measurement result displayed on the display unit 17 in the measurement mode from the input operation unit 14. Therefore, even if the acoustic signal AS is emitted at an appropriate volume, it is possible to suppress reception omission of the embedded information SC in the information terminal 15 carried by the user in the assumed reception area RA.

(16) The sound receiving device 30 is provided in a portable information terminal 15 having a transmitting unit 39 and an antenna 16 as output units. The transmission unit 39 outputs the compressed information CD from the antenna 16 by wireless communication. The acoustic transmission device 20 includes an antenna 13 for receiving a compressed information CD output by wireless communication from the antenna 16 and a receiving unit 20B. The first control unit 23 causes the compressor 24 to compress the original sound signal OS under the compression conditions determined based on the received compression information CD. According to this configuration, the acoustic transmission device 20 receives the compressed information CD transmitted by wireless communication from the portable information terminal 15 directly or via a server (not shown) at the antenna 13. Therefore, since the appropriate compression condition is determined in real time, even if the acoustic signal AS is emitted at an appropriate volume, the reception omission of the embedded information SC in the information terminal 15 carried by the user in the assumed reception area RA is suppressed. can.

(17) The sound receiving device 30 is provided in a portable information terminal 15 having a GPS receiver 18 for acquiring its own position information. The output unit outputs the compressed information CD and the position information. The sound transmission device 20 inputs or receives the compression information CD and the position information output by the output unit. The first control unit 23 causes the compressor 24 to compress the original sound signal OS under the compression conditions determined based on the compression information CD and the position information. According to this configuration, the response signal from the information terminal 15 in the assumed reception area RA can be selected based on the position information, so that it is appropriate to improve the reception performance of the embedded information SC suitable for the assumed reception area RA. It is possible to determine various compression conditions. Therefore, even if the acoustic signal AS is emitted from the speaker 12 at an appropriate volume, the acoustic receiving device 30 can suppress reception omission of the embedded information SC embedded in the acoustic signal AS.

<Other embodiments>
This embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

The compressor 24 is not limited to the configuration that compresses the original sound signal OS as in the above embodiment. As shown in FIG. 14, the acoustic signal Sas in which the embedded information SC is embedded in the original sound signal OS may be compressed by the compressor 24 before being emitted from the speaker 12. The compressor 24 inputs the acoustic signal Sas output by the embedded unit 28, and compresses the acoustic signal Sas under compression conditions. The compression condition changes one or both of the compression rate β and the threshold value SH. In this case, since it is not desired to compress the signal component of the embedded information SC included in the acoustic signal Sas, the threshold value SH shown in FIG. 2 is set in a range exceeding the maximum embedded strength PS. As a result, the embedded information SC having a sound intensity equal to or lower than the maximum embedded intensity PS is not compressed. Further, the amplifier 25 shown in FIG. 14 amplifies the acoustic signal Sas compressed by the compressor 24 at a specified amplification factor. Note that FIG. 14 shows an example of changing the configuration of the second embodiment. Similarly, in the first embodiment, the compressor 24 compresses the acoustic signal Sas and the amplifier 25 amplifies the compressed acoustic signal Sas. It may be configured.

-The compressor 24 may compress the original sound signal OS even in a portion below the threshold value SH with a small compression rate β. Under the compression conditions shown in FIG. 2, the compression rate β suddenly changes at the threshold SH, but as shown in FIG. 15, the portion below the threshold SH is compressed weaker than the compression rate β of the portion exceeding the threshold SH. It may be compressed at a rate. However, the portion having a weak compression ratio is set to a portion exceeding the maximum embedding strength PS. According to this configuration, it is possible to suppress deterioration of sound quality due to compression of the original sound signal OS or the acoustic signal AS. Further, in the configuration of FIG. 14, even if the acoustic signal AS is compressed under the compression conditions shown in FIG. 15, it is possible to prevent a decrease in the sound intensity of the embedded information SC.

-The compressor 24 may adjust both the threshold value SH and the compression rate β. Further, in the second embodiment, the compression information CD may be information indicating a combination of the threshold value SH and the compression rate β. In this case, the display unit 17 of the information terminal 15 that has received the compression information CD may display a threshold value in addition to the compression level indicating the compression rate β. Further, the combination of the compression rate β and the threshold value SH may be displayed as the compression level.

-In the second embodiment, the compressed information CDk received by the acoustic receiving device 30 is transmitted by wireless communication from the antenna 16, but the compressed information CDk may not be transmitted. In this case, the broadcaster can know the received compression rate from the compressed information CDk displayed on the display unit 17 of the information terminal 15. The operator can set an appropriate compression condition by operating the input operation unit 14 and instructing the sound transmission device 20 on the compression condition.

-In the second embodiment, the acoustic signal Sas in which the compression information CD1, CD2, ..., CDn are embedded in the original sound signal OS in advance at different compression rates is stored in the memory of the acoustic transmission device 20, and the memory is stored in the measurement mode. The acoustic signal AS may be emitted from the speaker 12 based on the acoustic signal Sa read from the speaker 12. Further, the acoustic signal Sa recorded in advance in the measurement mode may be input to the acoustic transmission device 20, and the acoustic transmission device 20 may cause the speaker 12 to emit the acoustic signal AS based on the acoustic signal Sa.

-In the second embodiment, the response signal may include reception performance information related to the individual reception performance of the information terminal 15. Here, the reception performance information may be, for example, the product name, product number, or the like of the information terminal 15. The product number may be the product number or the product number of the speaker or sound device. In addition, the reception performance level set in association with the product name or product number can be used as the reception performance information. The reception performance level is divided into, for example, 2 to 5 levels. According to this configuration, the acoustic transmission device 20 may set appropriate compression conditions in consideration of reception performance information. For example, when the acoustic transmission device 20 receives the compressed information CDk from the information terminal 15 whose reception performance level is higher than the standard level, the information terminal 15 having the standard reception performance level has the lowest compression rate that can be received. When setting a compression rate with a high degree of one-step compression, adjust to the lowest compression rate that can be received. Further, when the acoustic transmission device 20 receives the compressed information CDk from the information terminal 15 whose reception performance level is lower than the standard level, the information terminal 15 having the standard reception performance level has the lowest compression rate that can be received. When the compression rate with a high degree of one-step compression is set, the compression rate is adjusted to a higher degree of two-step compression than the lowest compression rate that can be received. Then, the first control unit 23 comprehensively determines each compression rate determined from the response signal from each information terminal 15, and determines an appropriate compression rate βp to be adopted. Although described in the example of determining the compression rate β, the appropriate threshold value SH may be determined or the combination of the appropriate threshold value SH and the compression rate β may be determined by using the reception performance information.

-In the second embodiment, the compressed information CDk and the position information of the information terminal 15 received by the GPS receiver 18 may be displayed on the display unit 17. Then, the first control unit 23 selects the compressed information CDk sent from the information terminal 15 in the assumed reception area RA based on the position information, and determines an appropriate compression condition based on the selected compressed information CDk. You may.

-In the second embodiment, when the position information is outside the assumed reception area RA, the received compressed information CDk may not be transmitted.
The sound receiving device 30 outputs all the compression information CDk, ..., CDn indicating a compression rate of βk or more, which is indicated by the lowest compression information CDk that can be extracted by the extraction unit 33 that constitutes an example of the extraction unit. May be good.

-In each embodiment, the compression rate may be changed for each of a plurality of bands of the acoustic signal Sas. For example, even if the midrange band, which is the vowel band of the announcement voice, is compressed by the first compression rate, and the high-pitched band, which is the consonant band, is compressed by the second compression rate, which is larger than the first compression rate. good.

An appropriate compression rate may be calculated based on the compression information CDk received on the information terminal 15, and the calculated appropriate compression rate may be output to the display unit 17 or the transmission unit 39.
-Masking by sound digital watermarking technology is not limited to forward masking, but may be reverse masking.

-The sound digital watermarking method is not limited to the diffusion method such as the echo diffusion method and the spread spectrum method. For example, an echo method, a periodic phase modulation method, a phase multiplexing method, an amplitude modulation method, or the like may be used. Further, the spread spectrum method may be a direct diffusion method or a frequency hopping method.

The diffusion code is not limited to the PN sequence (pseudo-noise sequence), and may be a Gold sequence or the longest sequence (M sequence) obtained by adding two types of PN sequences.

10 ... Acoustic communication system 11 ... Broadcasting device 12 ... Speaker as an example of sound emitting unit 13 ... Antenna 14 ... Input operation unit 15 ... Information terminal 16 ... Antenna constituting an example of output unit 17 ... Display as an example of output unit Unit 18 ... GPS receiver as an example of position information acquisition unit 20 ... Sound transmitter 20B ... Receiver unit 21 ... First input unit 22 ... Second input unit 23 ... First control unit 24 as an example of compression rate determination unit ... Compressor 25 ... Amplifier as an example of amplification unit 26 ... Diffusion code generator 27 ... Encoding unit 28 ... Embedded unit 29 ... Sound emission processing unit 30 ... Sound receiving device 31 ... Microphone as an example of sound collecting unit 32 ... No. 2 Control unit 33 ... Extraction unit 34 ... Decoding unit 35 ... Memory 36 ... Reference table 37 ... Display processing unit 38 ... Judgment unit 39 ... Transmission unit that constitutes an example of output unit IN ... Internet AS ... Sound signal Sas ... Sound signal OS ... Original sound signal OS1 ... Original sound SH, SH1 to SH5 ... Threshold OSc ... Original sound after compression OSa ... Original sound signal after amplification SC, SC1 to SCn ... Embedded information ID ... Identification information CD, CD1, CD2, ..., CDn, CDk … Compression information α1… Standard sound intensity (embedding intensity)
αp: Predetermined sound intensity (embedded strength)
β ... compression rate βp ... appropriate compression rate

Claims (16)

An acoustic communication system including an acoustic transmission device having a sound emitting unit that emits an acoustic signal in which embedded information is embedded, and an acoustic receiving device having a sound collecting unit that collects the acoustic signal.
The sound transmitter is
An embedded part that embeds embedded information in the original sound signal to generate an acoustic signal,
A sound emitting processing unit that emits the acoustic signal from the sound emitting unit, and
A compressor for compressing the original sound signal before the embedded information is embedded or the acoustic signal before being emitted from the sound emitting unit is provided.
The sound receiving device is
An extraction unit that receives the embedded information by extracting the embedded information from the acoustic signal collected by the sound collection unit, and an extraction unit.
An output section that outputs information and
An acoustic communication system including a control unit that outputs provided information corresponding to the embedded information extracted by the extraction unit to the output unit. The acoustic communication system according to claim 1, further comprising an amplification unit that amplifies the original sound signal compressed by the compressor or the acoustic signal. The compressor claims that the original sound signal or the portion exceeding the threshold value of the acoustic signal is compressed at a predetermined compression rate, and the portion below the threshold value is not compressed or is compressed at a compression rate smaller than the predetermined compression rate. Alternatively, the acoustic communication system according to claim 2. The acoustic communication system according to claim 3, wherein the compressor adjusts at least one of the threshold value and the compression rate. The acoustic communication system according to claim 4, wherein the threshold value is set to a value larger than the embedding strength when the embedding portion embeds the embedding information. The embedded unit detects an original sound having an amplitude equal to or higher than a set value among the input original sound signals, and embeds the embedded information in the detected original sound. Any one of claims 1 to 5. The acoustic communication system described in. The sound transmitter is
A test mode is provided in which the sound emitting processing unit emits a sound from the sound emitting unit by changing the compression condition of the compressor and embedding the embedded information including the compression information related to the compression condition.
The sound receiving device is
The extraction unit is provided with an output unit that outputs the compressed information included in the embedded information that can be extracted.
The acoustic transmission device includes the first control unit which inputs the compression information output by the output unit and causes the compressor to compress the original sound signal or the acoustic signal under compression conditions based on the compression information. The acoustic communication system according to any one of claim 6. The sound receiving device is provided in a portable information terminal having a display unit as the output unit.
The display unit displays the compression information and displays the compression information.
The acoustic transmission device includes an input operation unit for inputting the compression information displayed by the display unit.
The acoustic communication system according to claim 7, wherein the first control unit causes the compressor to compress the original sound signal or the acoustic signal under compression conditions determined based on the input compression information. The sound receiving device is provided in a portable information terminal having a transmitting unit and an antenna as the output unit.
The transmitting unit outputs the compressed information from the antenna by wireless communication.
The acoustic transmission device includes an antenna and a receiving unit that receive the compressed information output by the antenna by wireless communication.
The acoustic communication system according to claim 7 or 8, wherein the first control unit causes the compressor to compress the original sound signal or the acoustic signal under compression conditions determined based on the received compression information. The sound receiving device is provided in a portable information terminal having a position information acquisition unit that acquires its own position information.
The output unit outputs the compression information and the position information, and outputs the compression information and the position information.
The acoustic transmission device inputs or receives the compression information and the position information output by the output unit, and receives or receives the compression information.
The acoustic communication system according to any one of claims 7 to 9, wherein the first control unit determines the compression condition based on the compression information and the position information. The acoustic transmission device includes an encoding unit that encodes information including the compressed information into embedded information.
The embedded portion embeds the embedded information as the embedded information in the original sound signal.
The acoustic communication system according to any one of claims 7 to 10, wherein the extraction unit includes a decoding unit that decodes the embedded information extracted from the acoustic signal into information including the compression information. The acoustic transmission device in the acoustic communication system according to any one of claims 1 to 11.
An embedded unit that embeds embedded information in the original sound signal to generate an acoustic signal, and
A sound emitting processing unit that emits the acoustic signal from the sound emitting unit, and
An acoustic transmission device including a compressor that compresses the original sound signal before the embedded information is embedded or the acoustic signal before being emitted from the sound emitting unit. The acoustic receiving device in the acoustic communication system according to any one of claims 7 to 11.
A sound collecting unit that collects the acoustic signal and
An extraction unit that extracts embedded information from the acoustic signal collected by the sound collection unit, and an extraction unit.
A determination unit for determining whether the information included in the embedded information extracted by the extraction unit is identification information or compressed information, and
When the determination result of the determination unit is the compression information, the compression information in the embedded information extracted by the extraction unit is output to the first output unit, and the determination result of the determination unit is the identification information. In the case, an acoustic receiving device including a control unit that outputs the provided information corresponding to the identification information to the second output unit. A program to be executed by a computer included in the acoustic transmission device in the acoustic communication system according to any one of claims 1 to 11.
Computer,
An embedded unit that embeds embedded information in the original sound signal to generate an acoustic signal.
A sound emitting processing unit that emits the acoustic signal from the sound emitting unit,
A compressor that compresses the original sound signal before the embedded information is embedded or the acoustic signal before being emitted from the sound emitting unit.
A program for functioning as an amplification unit that amplifies the compressed original sound signal or the compressed acoustic signal before being emitted from the sound emitting unit. A program to be executed by a computer included in the acoustic receiving device in the acoustic communication system according to any one of claims 7 to 11.
Computer,
An extraction unit that extracts embedded information from the acoustic signal collected by the sound collection unit,
A determination unit that determines whether the information contained in the embedded information extracted by the extraction unit is identification information or compressed information.
When the determination result of the determination unit is the compression information, the compression information in the embedded information extracted by the extraction unit is output to the first output unit, and the determination result of the determination unit is the identification information. In this case, a program for functioning as a control unit that outputs the provided information corresponding to the identification information to the second output unit. A method of transmitting an acoustic signal in which an acoustic transmitter receives an acoustic signal transmitted by emitting an acoustic signal in which embedded information is embedded from the sound emitting unit, and the acoustic receiving device collects the sound in the sound collecting unit. And,
An embedding step in which the acoustic transmission device embeds embedded information in the original sound signal to generate an acoustic signal.
A sound emitting step in which the acoustic transmitting device emits the acoustic signal from the sound emitting unit, and
An extraction step in which the sound receiving device extracts the embedded information from the sound signal collected by the sound collecting unit, and
The sound receiving device includes a control step for outputting the provided information corresponding to the embedded information extracted in the extraction step to the output unit.
A method for transmitting an acoustic signal, further comprising a compression step in which the acoustic transmission device compresses the original sound signal before the embedded information is embedded or the acoustic signal before being emitted from the sound emitting unit.

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