JP7385533B2 - Acoustic receiving device, program, and acoustic signal receiving method in the acoustic receiving device - Google Patents

Description

The present invention relates to an acoustic receiving device, a program, and an acoustic signal receiving method in the acoustic receiving device that receive information embedded in an acoustic signal such as a sound wave.

As an acoustic communication system, a technique described in Patent Document 1 is known. The acoustic communication system described in Patent Document 1 includes an acoustic signal transmitting device that emits an acoustic signal in which identification information is embedded using an audio digital watermarking technique, and a microphone that collects (receives) the emitted acoustic signal. It is equipped with an acoustic receiving device (mobile terminal). The acoustic receiving device extracts identification information from the acoustic signal and outputs related information associated with the identification information to a display section or a sound emitting section, thereby providing the user with the relevant information. Embedded information in which identification information is encoded is embedded in the acoustic signal transmitted by the acoustic signal transmitting device. Therefore, the acoustic receiving device includes a decoding section that decodes embedded information extracted from the received acoustic signal into identification information. The acoustic receiving device is used by being built into a mobile terminal such as a smartphone or a tablet, for example.

Japanese Patent Application Publication No. 2016-153906

By the way, when the volume of the acoustic signal received by the acoustic receiving device is low, reception errors repeatedly occur. In this case, the decoding section within the audio receiving device repeatedly performs the decoding process as long as it receives the audio signal. In this way, the decoding unit repeats the decoding process without guaranteeing that the decoding process will be successful. Therefore, there is a problem that the battery power of the mobile terminal is wasted. Further, if the acoustic receiving device is configured to receive power from a commercial power source, there is a problem that power consumption increases.

Therefore, the present invention provides an audio receiving device, a program, and an audio signal receiving method in the audio receiving device that can suppress power consumption by optimizing whether or not to perform decoding processing.

Below, means for solving the above problems and their effects will be described.
(1) An acoustic receiving device that solves the above problem is an acoustic receiving device that uses a sound pickup section to collect an acoustic signal in which embedded information is embedded, and that adjusts the volume of the acoustic signal collected by the sound pickup section. a sound volume detection unit that performs detection; a determination unit that determines whether the detected sound volume detected by the volume detection unit exceeds a threshold; an extraction unit that performs an extraction process that extracts the embedded information from the audio signal; a decoding unit that performs a decoding process to decode embedded information into identification information, the decoding unit performing the decoding process when the detected volume exceeds the threshold, and the decoding unit performs the decoding process when the detected volume exceeds the threshold; In this case, the decoding process is not performed.

According to this configuration, when the detected volume of the acoustic signal collected by the sound collection section is less than or equal to the threshold value, the decoding section does not perform the decoding process. That is, if there is no audio signal or if the volume of the audio signal is too low and there is a high possibility that decoding will fail even if decoding is performed, wasteful decoding is not performed. Therefore, power consumption of the portable acoustic receiving device can be reduced. Therefore, the power consumption of the acoustic receiving device can be suppressed by optimizing whether or not to perform decoding processing.

(2) In the acoustic receiving device, the volume detection section may calculate an average volume per unit time of the acoustic signal, and the determination section may perform the determination by comparing the average volume with the threshold. good.

According to this configuration, the determination unit compares the average volume and the threshold value to make the determination. Therefore, even if there is a momentary small volume part due to the breathing of words in the audio or acoustic noise contained in the audio signal, by using the average volume per unit time, there will be no problem even if the audio signal is decoded. It is possible to appropriately determine whether or not the volume is appropriate.

(3) In the acoustic receiving device, the extraction unit may perform the extraction process when the detected volume exceeds the threshold, and may not perform the extraction process when the detected volume is equal to or less than the threshold. .

According to this configuration, when the detected volume of the acoustic signal collected by the sound collection section is below the threshold value, the extraction process is not performed in addition to the decoding process. That is, if there is no audio signal or if the volume of the audio signal is too low and there is a high possibility that the decoding process will fail, the extraction process is not performed in addition to the decoding process. Therefore, the power consumption of the acoustic receiving device can be further reduced.

(4) In the acoustic receiving device, the determining unit further determines whether or not the embedded information is present in the acoustic signal, and the decoding unit determines that even if the detected sound volume exceeds the threshold, there is no embedded information. If it is determined that the above decoding process is not performed.

According to this configuration, the determination unit determines the presence or absence of embedded information in the acoustic signal. If there is no embedded information, no decoding processing will be performed even if the detected volume exceeds the threshold. That is, if no embedded information is embedded in the audio signal, no wasteful decoding processing is performed. Therefore, power consumption of the acoustic receiving device can be reduced. Therefore, the power consumption of the acoustic receiving device can be suppressed by optimizing whether or not to perform decoding processing.

(5) In the acoustic receiving device, the determining section may determine whether or not the embedded information is present based on an extraction processing result by the extracting section or a decoding processing result by the decoding section.

According to this configuration, the presence or absence of embedded information is determined using the extraction processing result by the extraction section or the decoding processing result by the decoding section, so there is no need to separately provide a processing section to detect the presence or absence of embedded information. Moreover, it is possible to accurately determine the presence or absence of embedded information. Therefore, problems such as not performing decoding even though embedded information exists, or conversely, decoding processing occurring even though there is no embedded information, are reduced. Therefore, power consumption of the acoustic receiving device can be appropriately reduced.

(6) In the audio receiving device, the extraction unit may stand by without performing the extraction process if it is determined that there is no embedded information even if the detected volume exceeds the threshold.
According to this configuration, if it is determined that there is no embedded information even if the detected sound volume exceeds the threshold value, the decoding section waits without performing the decoding process, and the extracting section waits without performing the extraction process. Therefore, the power consumption of the acoustic receiving device can be further reduced.

(7) In the acoustic receiving device, when the detected sound volume exceeds the threshold, the output unit outputs provided information corresponding to the identification information obtained by decoding by the decoding unit, and the detected sound volume is equal to or less than the threshold. In this case, the information processing apparatus may include a control section that causes the output section to output a message indicating that there is no information to be provided.

According to this configuration, when the detected sound volume exceeds the threshold value, the provided information corresponding to the identification information obtained by decoding by the decoding section is output to the output section. On the other hand, if the detected sound volume is less than or equal to the threshold, the decoding section does not perform decoding, and a message indicating that there is no provided information is output to the output section. Not only can useful information be appropriately provided to users, but it is also possible to reduce errors in which inappropriate information is provided due to decoding failures. Therefore, the power consumption of the acoustic receiving device can be appropriately reduced, and useful information can be appropriately provided to the user.

(8) In the acoustic receiving device, the embedded information in which the same identification information is encoded is embedded in the acoustic signal multiple times in succession, and the decoding unit detects the embedded information each time it is successfully decoded. It is also possible to wait without decoding during the first standby time corresponding to the plurality of consecutive times.

According to this configuration, during the predetermined standby time, at least decoding is not performed even if the sound collection section receives an acoustic signal, so that the power consumption of the battery can be further reduced. In this case, if the volume exceeds the threshold, if the embedded information is successfully decoded the first time out of multiple successive times, the embedded information will continue to contain the same identification information for the remaining number of repetitions. Therefore, by waiting without decoding during that time, the number of unnecessary decoding operations can be reduced. Note that the predetermined waiting time corresponding to the plurality of times is not limited to the waiting time corresponding to the plurality of times, but may be the waiting time corresponding to the number of times less than the plurality of times by one or two times.

(9) In the acoustic receiving device, when the number of consecutive times the determination unit determines that the detected volume is equal to or less than the threshold value reaches a set number of times, the volume detection unit detects the detected volume during the second standby time. It is also possible to wait without performing detection.

According to this configuration, when the number of consecutive times the detected volume is determined to be less than or equal to the threshold value reaches the set number of times, the detected volume is not detected during the second standby time. If the embedded information cannot be correctly decoded due to noise surrounding the user carrying the mobile terminal, not only is the decoding not performed, but also unnecessary detection and determination of the detected volume is not performed. Therefore, the power consumption of the battery of the mobile terminal can be further reduced.

(10) The acoustic receiving device is included in a mobile terminal having a battery, and includes a control section that detects a remaining amount of the battery, and the control section is configured to detect a remaining amount of the battery when the remaining amount of the battery is a first remaining amount. The second standby time may be set to be longer when the second remaining amount is smaller than the first remaining amount.

According to this configuration, the second standby time is set longer as the remaining battery level of the mobile terminal is lower, and the power consumption of the battery can be reduced.
(11) A program for solving the above problem is a program that causes a computer included in an audio receiving device that collects an audio signal in which embedded information is embedded in a sound collecting section to be executed, and the program causes the computer to A volume detection unit that detects the volume of the audio signal collected by the sound unit, a determination unit that determines whether the detected volume detected by the volume detection unit exceeds a threshold, and extracts the embedded information from the audio signal. an extraction unit that performs an extraction process to perform an extraction process, when the detected sound volume exceeds the threshold value, performs a decoding process to decode the embedded information into identification information, and when the detected sound volume is below the threshold value, performs the decoding process; It functions as a decoding section that does not perform any decoding. Therefore, by having a computer execute the program, it is possible to suppress the power consumption of the acoustic receiving device by optimizing whether or not to perform decoding processing.

(12) An acoustic signal receiving method in an acoustic receiving device that solves the above problem is an acoustic signal receiving method in an acoustic receiving device in which an acoustic signal in which embedded information is embedded is collected by a sound collecting section, a volume detection step of detecting the volume of the audio signal collected by the unit; a determination step of determining whether the detected volume detected in the volume detection step exceeds a threshold; and a determination step of determining the embedded information from the audio signal. an extraction step of performing an extraction process to extract; if the detected sound volume exceeds the threshold value, a decoding process of decoding the embedded information into identification information; and if the detected sound volume is below the threshold value, the decoding step; and a decoding step that does not perform any processing. Therefore, the power consumption of the acoustic receiving device can be suppressed by optimizing whether or not to perform decoding processing.

According to the present invention, it is possible to suppress power consumption of an acoustic receiving device by appropriately determining whether or not to decode embedded information.

FIG. 1 is a schematic diagram showing an acoustic communication system in a first embodiment. FIG. 1 is a schematic diagram showing an acoustic communication system. FIG. 1 is a block diagram showing the configuration of an acoustic communication system. A graph explaining the echo diffusion method. 5 is a flowchart showing acoustic signal reception processing. FIG. 2 is a block diagram showing the configuration of an acoustic receiving device in a second embodiment. 5 is a flowchart showing acoustic signal reception processing.

(First embodiment)
The acoustic communication system 10 of the first embodiment will be described below with reference to FIGS. 1 to 5.
As shown in FIG. 1, the acoustic communication system 10 includes an acoustic transmitter 20 having a speaker 12 as an example of one or more sound emitting units, and a mobile phone that receives an acoustic signal AS emitted from the speaker 12. The terminal 15 includes an acoustic receiving device 30 built into the terminal 15. Embedded information SC (see FIG. 2) is embedded in the acoustic signal AS. The user carries the portable mobile terminal 15 with him when he moves. The acoustic receiving device 30 built into the mobile terminal 15 receives the embedded information SC embedded in the acoustic signal AS. For example, a user uses the audio receiving device 30 of the mobile terminal 15 to receive an audio signal AS broadcast from a speaker 12 of a broadcasting station such as a station, a shopping mall, a public facility, or the like. The mobile terminal 15 is, for example, a mobile phone, a smartphone, a tablet, a notebook computer, or the like. The acoustic receiving device 30 acquires the provided information provided by the broadcaster based on the embedded information SC embedded in the acoustic signal AS. In this way, the user using the audio receiving device 30 can receive the information provided by the broadcasting entity.

The broadcasting entity is, for example, a person or business operator who broadcasts the audio signal AS, or a person or business operator who requests the broadcasting of the audio signal AS. The broadcasting entity may be a person who generates the audio signal AS himself or a business operator. The broadcasting entity does not have to be a person who generates the audio signal AS himself or a business operator. For example, broadcasting entities include businesses that operate stores, businesses that operate public transportation such as railways, businesses or organizations that operate learning facilities including schools, businesses that operate museums and exhibitions, businesses that operate swimming pools, etc. These include businesses that operate leisure facilities, businesses that operate accommodation facilities, and local governments that broadcast disaster warnings.

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 provision information is stored on a server on the Internet IN. In other examples, the provided information is stored in the acoustic receiving device 30. Examples of provided information are listed below. If the broadcasting entity is a business that operates a store, the provided information is detailed content of products in the store. When the broadcasting entity is a local government, the provided information is a map showing evacuation locations in the event of a disaster. When the broadcasting entity is a business that operates an exhibition, the provided information is information showing details of the exhibit. The provided information may be an announcement that is broadcast as an acoustic signal AS and translated into another language. When the broadcasting entity is a movie theater, the provided information may be subtitles of movie lines. The provided information may be link information (for example, URL: Uniform Resource Locator) indicating a location 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 mobile terminal 15, or may be emitted from headphones or earphones connected to the earphone jack of the mobile terminal 15, or may be emitted from the speaker of the mobile terminal 15. You can.

The acoustic signal AS is a sound wave containing frequencies in the audible range. Embedded information SC is embedded in the audio signal AS as an audio digital watermark. The acoustic signal AS is broadcast from the broadcasting device 11. Examples of the acoustic signal AS include announcements, warnings, sound signs for the general public or visually impaired people, BGM (background music), explanatory sounds output at museums or exhibitions, and broadcast programs. The data length of one piece of embedded information SC embedded with an audio digital watermark is, for example, about 8 bits. In addition, acoustic noise may be added to the acoustic signal AS due to various causes such as the distance in which the acoustic signal AS is propagated, the volume of the sound emitted, the presence or absence of obstacles, and the noise surrounding the user who carries the mobile terminal 15. or the volume of the acoustic signal AS becomes excessively low. In this case, there is a high possibility that the mobile terminal 15 cannot receive the embedded information SC embedded in the acoustic signal AS. Therefore, the acoustic transmitting device 20 repeatedly emits the same embedded information SC multiple times so that even if the acoustic receiving device 30 fails to receive the embedded information SC once, it can receive the embedded information SC the next time.

As shown in FIG. 2, the acoustic transmitting device 20 includes a device main body 20A and a speaker 12 connected to the device main body 20A. The acoustic transmitting device 20 generates an acoustic signal Sas, which is a digital signal, by embedding embedded information SC in the original sound signal OS (see FIG. 3), and emits an acoustic signal AS based on the acoustic signal Sas from the speaker 12. . The acoustic signal AS is composed of an original sound signal OS made of voice or music, and a plurality of embedded information SC embedded one by one for each original sound in the original sound signal OS.

The mobile terminal 15 has a built-in acoustic receiving device 30. The acoustic receiving device 30 includes an application (software) installed on the mobile terminal 15 and a CPU (not shown) that executes the application. The mobile terminal 15 includes a microphone 31 as an example of a sound collection section. The mobile terminal 15 collects the acoustic signal AS using the microphone 31. Furthermore, the acoustic receiving device 30 takes in the acoustic signal AS picked up by the microphone 31 as an electrical signal, and extracts the embedded information SC from the acoustic signal Sas made of the electrical signal. The acoustic receiving device 30 restores the embedded information SC to identification information ID. The acoustic receiving device 30 outputs provided information corresponding to the identification information ID to the mobile terminal 15. As a result, the user can view the provided information displayed on the display section 17 (see FIG. 3) of the mobile terminal 15, or use the headphones, earphones, or speakers (all not shown) connected to the earphone jack of the mobile terminal 15. ) You can listen to the provided information output from.

Next, with reference to FIG. 3, the configurations of the acoustic transmitter 20 and the acoustic receiver 30 will be described. In this embodiment, in order to distinguish between a sound signal caused by a sound wave transmitted in space and an electric signal, a sound wave is referred to as an acoustic signal AS, and an electric signal is referred to as an acoustic signal Sas. Further, the original sound signal OS is an electrical signal. Further, the embedded information SC is a sound wave embedded in the acoustic signal AS, and an electric signal embedded in the acoustic signal Sas.

The acoustic transmitting device 20 embeds the identification information ID in the original sound signal OS using audio digital watermarking technology, and emits the sound from the speaker 12 as an acoustic signal AS. The identification information ID is embedded in the acoustic signal AS as embedded information SC. The acoustic transmitting device 20 may be built in the broadcasting device 11 that includes a speaker 12 that outputs the acoustic signal AS as a sound wave. On the other hand, the acoustic receiving device 30 is built into a mobile terminal 15 such as a smartphone. The acoustic receiving device 30 extracts embedded information SC from the acoustic signal Sas picked up by the microphone 31. This acoustic receiving device 30 is configured as a device built into the mobile terminal 15, but may be the mobile terminal 15 itself.

First, with reference to FIG. 3, the detailed configuration of the acoustic transmitter 20 will be described.
The acoustic transmitter 20 includes a first input section 21 into which the original sound signal OS is input, and a second input section 22 into which the identification information ID is input. This acoustic transmitting device 20 includes a first control section 23 that controls the acoustic transmitting device 20 in an integrated manner. The acoustic transmitting device 20 also includes a spreading code generator 26, an encoding section 27, an embedding section 28 having a function of convolving the embedding information SC into the original sound signal OS, and a transmitting section 29 including an amplifier and the like.

Further, the spreading code generator 26 generates a spreading code. The spreading code may be any code. For example, a PN sequence is used as the spreading code. The PN sequence is a sequence called a pseudo-noise sequence.

The encoding unit 27 encodes the identification information ID into embedded information SC. The embedded information SC in which the identification information ID is encoded is, for example, 8-bit information.
The embedding unit 28 embeds the embedding information SC into the audio signal AS by convolving the embedding information SC into 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) in which embedded information SC is embedded. Further, the original sound signal OS of this example has a frequency in the audible range. Note that the original sound signal OS may have a frequency in an inaudible range.

The method by which the embedding unit 28 convolutes and embeds the embedding information SC into the original sound signal OS is an echo diffusion method or a spread spectrum method. The embedding method may be another method. Note that it is preferable to adopt a spreading method in which a PN sequence spreading code functions as a secret key in order to improve the confidentiality of the embedded information SC.

The acoustic transmitter 20 includes an electronic board on which a CPU, 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 section 23, 26 to 28 made of software is configured within the acoustic transmitter 20. In other words, the program stored in the memory within the acoustic transmitter 20 causes the computer to function as each of the units 23, 26-28. Note that each section 23, 26 to 28 may be configured by software and hardware, or may be configured by hardware.

Next, with reference to FIG. 3, the mobile terminal 15 incorporating the acoustic receiving device 30 will be described.
The mobile terminal 15 includes a microphone 31 that functions as an example of a sound collection unit that collects the acoustic signal AS, an operation unit 16 that is operated by the user, and a display unit 17 that serves as an example of an output unit that outputs provided information and the like. , a battery BT, and various functional units that function as a mobile terminal. The various functional units include a telephone functional unit, a mail functional unit, an Internet communication functional unit, a GPS functional unit, and the like.

The acoustic receiving device 30 includes a second control section 32 that controls the acoustic receiving device 30 in an integrated manner. The acoustic receiving device 30 also includes a receiving section 33 including an amplifier and the like, which converts the acoustic signal AS picked up by the microphone 31 into an acoustic signal Sas which is an electrical signal.

The acoustic reception device 30 includes a volume detection unit 34 that detects the volume of the audio signal Sas output from the reception unit 33, and a determination unit 35 that determines whether the detected volume detected by the volume detection unit 34 exceeds a threshold value. Equipped with The acoustic receiving device 30 also includes an extraction unit 36 that extracts embedded information SC from the acoustic signal Sas input from the receiving unit 33, and an extraction unit 36 that converts the embedded information SC extracted from the acoustic signal Sas by the extraction unit 36 into identification information ID. and a decoding section 37 for decoding. Furthermore, the acoustic receiving device 30 includes a memory 38 that stores necessary data and setting values including the reference table DT, and a display processing section 39 that performs a process of displaying provided information and the like on the display section 17. The set values include a threshold for determination, a set number of times described below, a first standby time T1, a second standby time T2, and the like.

The acoustic signal Sas output from the receiving section 33 is input to the volume detecting section 34 and the extracting section 36. The volume detection unit 34 detects the volume of the acoustic signal AS picked up by the microphone 31. Specifically, the volume detection unit 34 calculates the average level of volume per unit time of the audio signal Sas based on the audio signal Sas input from the reception unit 33, thereby calculating the average level of the audio signal AS picked up by the microphone 31. Detect volume. The determining unit 35 determines whether the average volume, which is an example of the detected volume detected by the volume detecting unit 34, exceeds a threshold value. Here, the upper limit of the volume below a predetermined value at which it is considered that the embedded information SC cannot be correctly decoded into the identification information ID is set as the threshold value. In this example, by determining the average volume of the audio signal Sas, it is possible to determine whether the volume of the embedded information SC embedded at a certain ratio of the volume of the original sound in the audio signal Sas is a volume that can be correctly decoded. Indirectly determine whether

Here, the threshold value can be set to an appropriate value from the viewpoint of power saving and utilization of provided information. For example, the threshold may be set to a value that allows selection not to decode when the probability of incorrect decoding is 100%. Further, the threshold value may be set to a value that allows selection of not decoding when the probability of incorrect decoding is 50% or more.

The determination unit 35 activates the extraction unit 36 and the decoding unit 37 when the average volume of the audio signal Sas exceeds the threshold value. On the other hand, the determination unit 35 does not activate the extraction unit 36 and the decoding unit 37 if the average volume of the acoustic signal Sas does not exceed the threshold. Specifically, when the average volume exceeds the threshold, the determination unit 35 outputs a determination value “1” to the extraction unit 36 and the decoding unit 37. On the other hand, if the average volume does not exceed the threshold, the determination unit 35 outputs a determination value of “0” to the extraction unit 36 and the decoding unit 37.

The extraction unit 36 starts when the judgment value "1" is input, and does not start or stops starting when the judgment value "0" is input. Further, the decoding unit 37 is activated when the determination value "1" is input, and does not activate or stops activation when the determination value "0" is input. In this way, when the extraction section 36 is activated, the decoding section 37 is also activated, whereas when the extraction section 36 is not activated, the decoding section 37 is also not activated. Therefore, while the audio receiving device 30 is activated, the volume detection unit 34 and the determination unit 35 are activated, but while the audio signal Sas whose average volume is below the threshold is being received, the extraction unit 36 and the decoding unit 37 are activated. does not start. Then, while the audio receiving device 30 is activated, the extraction unit 36 and the decoding unit 37 are activated only when an audio signal Sas whose average volume exceeds the threshold is received.

The extraction unit 36 extracts the embedded information SC from the acoustic signal Sas using a method according to the diffusion method that the acoustic communication system 10 employs as a method for embedding the embedded information SC. When the embedding method is an echo diffusion method, the extraction unit 36 extracts the embedding information SC, which is spread in the time axis as an echo of the original sound included in the original sound signal OS, from the acoustic signal Sas. Specifically, the extraction unit 36 performs cepstral transformation on the acoustic signal Sas to extract embedded information SC consisting of a string of binary "0" and "1" determined from the time intervals of the plurality of extracted peaks. . Further, when the embedding method is a spread spectrum method, the extraction unit 36 extracts the embedded information SC from the acoustic signal Sas by demodulating the embedded information SC that has been spectrally spread to the original sound included in the original sound signal OS. do. Further, when the embedding method is another method, the extraction unit 36 extracts the embedding information SC from the acoustic signal Sas using an extraction method corresponding to the other method. Note that details of the echo diffusion method will be described later.

The decoding unit 37 decodes the embedded information SC into identification information ID. The decoding unit 37 decodes the embedded information SC into identification information ID by despreading the spread using the spreading code adopted by the encoding unit 27 of the audio transmitting device 20. Specifically, the decoding unit 37 uses a spreading code to cross-correlate the PN sequence spread by the embedding unit 28 with the same PN sequence, thereby converting the embedded information SC into the identification information ID before encoding. Decrypt. The decoding unit 37 sends the decoded identification information ID to the second control unit 32.

The acoustic receiving device 30 includes an electronic board on which a CPU, a memory 38, and the like are mounted. The memory 38 stores a program for acoustic signal reception processing (see FIG. 5). By executing the program read from the memory 38, the CPU functions as each section 32 to 37, 39 comprised of software in the acoustic receiving device 30. That is, the program stored in the memory 38 in the acoustic receiving device 30 causes the computer to function as each of the units 32 to 37 and 39. Specifically, the program stored in the memory 38 in the audio receiving device 30 causes the computer to function as the second control section 32, the volume detection section 34, the determination section 35, the extraction section 36, the decoding section 37, and the display processing section 39. let Note that among the units 32 to 37, 39, one or both of the receiving unit 33 and the display processing unit 39 may be hardware included in the mobile terminal 15. Further, each of the units 32, 34 to 37 may be configured by software and hardware, or may be configured by hardware.

Next, with reference to FIG. 4, an embedding method for embedding the embedding information SC into the acoustic signal Sas will be described using an echo diffusion method as an example. FIG. 4 shows the original sound and echo kernel obtained by the echo diffusion method. Divide the time axis into multiple time frames from the offset time when the original sound is "1", and use a PN sequence for the multiple time frames to correspond to the binary values of "0" and "1". Multiple peaks are located at different time differences. α is the embedding strength when the diffusion length is L. That is, α is the amplitude of the PN sequence forming the echo. In the echo diffusion method, the same detection accuracy is ensured even if the embedding strength α is set to 1/L of the embedding strength of a single echo in the echo method. The digital watermark embedding process is performed by the embedding unit 28 convolving the original signal and the echo kernel. Further, at the time of detection, the extraction unit 36 performs cepstral transformation on the signal of the embedded information SC embedded in the original signal. On the other hand, when using the spread spectrum method, the embedding unit 28 uses a PN sequence to spread the signal over an occupied band several ten times larger than the carrier wave before modulation. At the time of detection, the extraction unit 36 performs despreading to extract the embedded information SC. Here, the unit strength of the original sound "1" corresponds to the volume of the original sound in the acoustic signal Sas, and the embedding strength α corresponds to the volume of the signal component of the embedded information SC. Then, the embedding information SC is embedded in the original sound signal OS at a volume that is a constant ratio α to the volume of the original sound.

Next, the operation of the acoustic communication system 10 will be explained.
Users carrying mobile terminals 15 move around stations and shopping streets, watch movies in art galleries, museums, movie theaters, and watch games in facilities such as stadiums and conference halls. The user operates the operation unit 16 to activate the audio receiving device 30 while the mobile terminal 15 is powered on. An acoustic signal AS is emitted from a speaker 12 of a broadcasting device 11 mainly used for broadcasting in an area where users move or in a facility where they view music. The mobile terminal 15 collects the acoustic signal AS with the microphone 31. The acoustic receiving device 30 provides the user with the provided information by outputting the provided information corresponding to the embedded information SC embedded in the received acoustic signal AS to the mobile terminal 15.

When the audio receiving device 30 is activated while the mobile terminal 15 is powered on, the CPU of the mobile terminal 15 executes the audio signal reception processing routine program shown in FIG. When the acoustic signal AS is emitted from the speaker 12 of the acoustic transmitter 20, the microphone 31 of the mobile terminal 15, which is powered on, picks up the acoustic signal AS. The receiving section 33 amplifies the acoustic signal Sas from the microphone 31 and outputs it to the volume detecting section 34 and the extracting section 36 . The extraction unit 36 and the decoding unit 37 do not start up while the acoustic receiving device 30 is started up as long as the judgment value input from the judgment unit 35 is “0”. The extraction unit 36 that is not activated does not accept the acoustic signal Sas.

Hereinafter, with reference to FIG. 5, the operation of the acoustic receiving device 30, which is driven by the CPU of the mobile terminal 15 executing a program, will be described. The program corresponds to an application that is installed in the mobile terminal 15 and causes the CPU (computer) to function as each of the units 32 to 39 configuring the acoustic receiving device 30. The CPU executes the program at predetermined unit time intervals (for example, within a range of several milliseconds to several tens of milliseconds).

First, in step S11, the CPU determines whether or not the acoustic signal Sas has been received. That is, the CPU determines whether the receiving section 33 has input the acoustic signal Sas. If the acoustic signal Sas is not received, the process remains on standby; if the acoustic signal Sas is received, the process proceeds to step S12.

In the next step S12, the CPU determines whether the waiting time has elapsed. Here, the waiting time includes a first waiting time T1 that is set when the determination result of step S14 is a positive determination in the process before the previous time, and a first waiting time T1 that is set when the determination result of step S14 is a negative determination in the process before the previous time. A second waiting time T2 is included, which is set when the number of consecutive times reaches a set number of times. The first standby time T1 is set to a time corresponding to a plurality of times that the embedded information SC, in which the same identification information ID is encoded, is repeatedly embedded in the audio signal AS. The first standby time T1 is set, for example, to a time within a range of 0.1 to 2 seconds. In addition, the second standby time T2 is set when the number of consecutive times that the detected sound volume becomes below the threshold reaches a set number of times, and for a while after that, the sound signal AS does not reach the sound volume that the detected sound volume exceeds the threshold. Set when there is no prospect of return. For example, if the position of the mobile terminal 15 carried by the user is far from the speaker 12 of the broadcasting device 11, the number of consecutive times the detected sound volume becomes equal to or less than the threshold value may reach the set number of times. On the other hand, if an obstacle temporarily exists between the speaker 12 and the mobile terminal 15, or if temporary acoustic noise rides on the acoustic signal AS, the number of times the detected volume falls below the threshold is only one. There are cases where the number of consecutive times does not reach the set number of times, such as when the game ends. In this case, the second waiting time T2 is not set. Therefore, an affirmative determination is made in step S12 next time as well. If the waiting time has elapsed, the CPU proceeds to step S13, and if the waiting time has not elapsed, the CPU ends the routine. Note that during the standby period for waiting for the standby time to elapse, the power consumption of the CPU that executes the calculation of the average volume (step S13) and the determination process (step S14) is saved.

In step S13, the CPU calculates the average volume. This process is performed by the volume detection section 34. The volume detection unit 34 samples the volume at N points per unit time of the audio signal Sas, integrates the volume at the N points, and divides the total value by N, thereby calculating the average volume of the audio signal Sas. The average volume per unit time of this acoustic signal Sas corresponds to an example of the detected volume. In addition, in this embodiment, the process of this step S13 corresponds to an example of the volume detection step.

In the next step S14, the CPU determines whether the average volume exceeds a threshold value. This determination is made by the determination unit 35. If the average volume exceeds the threshold, the process advances to step S15, and if the average volume does not exceed the threshold, the process advances to step S18. Here, if the average sound volume exceeds the threshold value, the determination section 35 outputs a determination value of "1", so the extraction section 36 and the decoding section 37 are activated. On the other hand, if the average volume does not exceed the threshold, the determination unit 35 outputs a determination value of “0”, so the extraction unit 36 and the decoding unit 37 are not activated or stop activation. In addition, in this embodiment, the process of this step S14 corresponds to an example of a determination step.

In step S15, the CPU extracts embedded information SC. This process is performed by the extraction unit 36. The extraction unit 36 extracts embedded information SC from the audio signal Sas input from the reception unit 33. The embedded information SC is extracted using an extraction method depending on the spreading method employed, such as an echo diffusion method or a spread spectrum method. Note that in this embodiment, the process of step S15 corresponds to an example of an extraction step.

In the next step S16, the CPU executes decoding processing. This process is performed by the decoding section 37. The decoding unit 37 decodes the embedded information SC into the identification information ID before encoding by cross-correlating the embedded information SC with the same PN sequence as the PN sequence spread by the embedding unit 28. do. The decoding unit 37 sends the decoded identification information ID to the second control unit 32.

In the next step S17, the CPU causes the output unit to output the provision information corresponding to the identification information ID. This process is performed by the second control unit 32. The second control unit 32 obtains the provision information corresponding to the identification information ID by referring to the reference table DT (see FIG. 3) stored in the memory 38 based on the identification information ID. Then, the second control unit 32 outputs the provided information by display or audio. That is, the second control unit 32 causes the display unit 17 to display the provided information via the display processing unit 39, and causes the sound output processing unit to display the provided information on the headphones or earphones connected to the earphone jack, or the speaker (any one) of the mobile terminal 15. (not shown) to emit provided information.

For example, the display unit 17 of the mobile terminal 15 may display any one of store information, product information, coupon information, a map, a description of an exhibit, a translated text of the announcement, etc. related to the announcement of the original sound signal OS. Multiple items are displayed. In addition, from the headphones, earphones, or speakers connected to the mobile terminal 15, any one or more of store information, product information, coupon information, route guidance voice, translated voice of the announcement, etc. related to the announcement of the original sound signal OS is transmitted. Multiple sounds are emitted. For example, when the original sound signal OS is music such as BMG, and when the user carrying the mobile terminal 15 is moving around a shopping district or department store, among the store information, product information, coupon information, map, and route guidance audio, One or more are displayed or sounded on the mobile terminal 15. In addition, if the original sound signal OS is music such as BMG, and the user carrying the mobile terminal 15 is inside a building such as an art gallery or a museum, inside a station, or inside a facility such as a stadium or conference hall, explanations may be provided. One or more of sentences, multilingual explanatory voices, guidance sentences, multilingual guidance voices, etc. are displayed or emitted on the mobile terminal 15.

On the other hand, if the average volume does not exceed the threshold, the CPU sets a standby time in step S18. Here, the CPU sets the second waiting time T2. In other words, even if the volume of the acoustic signal Sas exceeds the threshold, if it is determined that the embedded information SC is not embedded in the acoustic signal Sas, the determination unit 35 outputs the determination value "0". , the extraction section 36 and the decoding section 37 are stopped from being activated, or are kept in a stopped state. Then, a standby time for continuing the stopped state is set. Then, in the next step S19, the CPU causes the output unit to output a message to the effect that there is no provided information. This process is performed by the second control unit 32. The second control unit 32 outputs the fact that there is no provided information by display or sound. That is, the second control unit 32 causes the display unit 17 to display that there is no information to be provided via the display processing unit 39, or causes the sound output processing unit to display the headphones or earphones connected to the earphone jack, or the mobile terminal 15. For example, a speaker (all not shown) may emit a sound indicating that there is no information to be provided. In addition to outputting "No information provided," the "no information provided" may also include information such as "Unable to receive," "Unable to detect," or "Out of reception area." . In addition, in this embodiment, the processing of steps S17 and S19 corresponds to an example of an output step.

Furthermore, in the present embodiment, embedded information SC in which the same identification information ID is encoded is consecutively embedded in the acoustic signal AS emitted from the speaker 12 of the acoustic transmitter 20 a plurality of times. That is, the microphone 31 of the acoustic receiving device 30 consecutively receives the embedded information SC encoded with the same identification information ID a plurality of times. If the average sound volume, which is the detected sound volume, exceeds the threshold (affirmative determination in step S14), the second control unit 32 sets the embedded information SC to the second level according to a plurality of consecutive times, every time the decoding unit 37 succeeds in decoding. 1. Set standby time T1. In this case, if the embedded information SC is successfully decoded the first time out of a plurality of consecutive embedded information SCs, then the embedded information SC will remain the same identification information for the remaining number of times the embedded information SC is repeated. Since the data is decoded into an ID, the number of unnecessary decodings can be reduced by waiting without decoding during that time.

Here, the first waiting time T1 according to the plurality of times is not limited to the waiting time corresponding to the remaining number of repetitions ((multiple times - 1) times) among the plurality of times, but is one time or more than the number of repetitions. The waiting time may be equivalent to two times less. For example, if the number of consecutive embedded information SCs with the same identification information ID is n times, and the interval time between embedded information SCs is t seconds, then the nth embedded information SC from the time when the first embedded information SC is received is The first standby time T1 is, for example, (n-1)t seconds, which is a time corresponding to (n-1) times, which is the remaining number of repetitions until the reception timing of receiving the information SC. Note that the first standby time T1 may be set to an appropriate value within the range of (nk)t≦T1<nt. However, k is a natural number satisfying nk≧1. In this way, each time the decoding unit 37 succeeds in decoding, it waits without performing decoding for a first waiting time T1 corresponding to the number of consecutive embedded information SCs.

Further, if the average volume, which is the detected volume, is less than or equal to the threshold (negative determination in step S14), the CPU counts the consecutive number of times the detected volume does not exceed the threshold using a counter (not shown). Then, when the consecutive number of times reaches the set number of times, the CPU sets the second standby time T2. The second standby time T2 is set to be longer than the first standby time T1 (T2>T1).

Further, the second control unit 32 may detect the remaining amount of the battery BT and adjust the length of the second standby time T2 according to the remaining amount of the battery BT. For example, the second control unit 32 sets the second standby time T2 more when the remaining amount of the battery BT is at the second remaining amount, which is less than the first remaining amount, than when the remaining amount of the battery BT is at the first remaining amount. Set it to a longer time. In this case, the second standby time T2 may be set in multiple stages so as to change stepwise with respect to the remaining battery power, or may be set so as to change continuously with changes in the remaining battery power. It's okay.

Further, the second control unit 32 may change the number of consecutive times depending on the remaining amount of the battery BT. For example, the second control unit 32 controls the number of consecutive times to be smaller when the remaining amount of the battery BT is at the second remaining amount, which is less than the first remaining amount, than when the remaining amount of the battery BT is the first remaining amount. Set to . Therefore, as the remaining amount of the battery BT decreases, the number of consecutive times that the detected sound volume becomes equal to or lower than the threshold value decreases, and the second standby time T2 starts earlier.

According to the mobile terminal 15 incorporating the audio receiving device 30 of the present embodiment, when the volume of the received audio signal Sas exceeds the threshold and the detected volume is such that the embedded information SC can be correctly decoded into the identification information ID, As long as the extraction section 36 and the decoding section 37 are activated. On the other hand, if the volume of the received acoustic signal Sas is below the threshold and the detected volume is such that there is a high possibility that the embedded information SC cannot be correctly decoded into the identification information ID, the extraction unit 36 and the decoding unit 37 are not activated. Therefore, wasteful consumption of battery power of the mobile terminal 15 can be reduced.

Therefore, even if the user carries the mobile terminal 15 with the acoustic receiving device 30 activated, the user does not need to worry so much about the power consumption of the battery BT. As a result, useful information can be obtained from the mobile terminal 15 at a shopping mall, facility, etc. while the acoustic receiving device 30 is activated. Furthermore, even though the volume of the acoustic signal Sas is too low, the embedded information SC is forcibly decoded, resulting in an error output in which incorrect provided information corresponding to the incorrect identification information ID is output from the mobile terminal 15. The frequency of occurrence decreases.

As described in detail above, according to the first embodiment, the following effects can be obtained.
(1) The acoustic receiving device 30 is provided in the mobile terminal 15 having a microphone 31 and a battery BT, and receives an acoustic signal AS embedded with embedded information SC in which identification information ID is encoded. The acoustic receiving device 30 includes a volume detection unit 34 that detects the volume of the audio signal Sas picked up by the microphone 31, a determination unit 35 that determines whether the detected volume detected by the volume detection unit 34 exceeds a threshold value. It includes an extraction section 36 that performs an extraction process to extract embedded information SC from the acoustic signal Sas, and a decoding section 37 that performs a decoding process that decodes the embedded information SC into identification information ID. The decoding unit 37 performs the decoding process when the detected volume exceeds the threshold value, and does not perform the decoding process when the detected volume is below the threshold value. According to this configuration, if the acoustic signal Sas is not received or the volume of the acoustic signal Sas is too small and there is a high possibility that decoding the embedded information SC into the identification information ID will fail, the decoding is unnecessary. No processing takes place. Therefore, power consumption of the battery BT of the mobile terminal 15 can be reduced. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be suppressed by optimizing whether or not to perform the decoding process.

(2) The volume detection unit 34 calculates the average volume per unit time of the acoustic signal Sas. The determination unit 35 makes a determination by comparing the average volume and a threshold value. According to this configuration, the determination unit 35 makes a determination by comparing the average volume with a threshold value. Therefore, even if there is a momentary small volume part due to the breathing of words in the audio or acoustic noise contained in the audio signal Sas, the audio signal Sas can be decoded by using the average volume per unit time. It is possible to appropriately determine whether or not the volume is appropriate without any problems.

(3) The extraction unit 36 performs the extraction process when the detected volume exceeds the threshold, and does not perform the extraction process when the detected volume is below the threshold. According to this configuration, when the detected volume of the acoustic signal Sas picked up by the microphone 31 is below the threshold value, the extraction process is not performed in addition to the decoding process. That is, if the acoustic signal Sas is not received, or if the volume of the acoustic signal Sas is too small and there is a high possibility that decoding the embedded information SC into the identification information ID will fail, the extraction process is performed in addition to the decoding process. Not done. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be further reduced.

(4) The mobile terminal 15 has a display unit 17 and a sound emitting unit such as an earphone jack and a speaker as an output unit that outputs the provided information corresponding to the identification information ID obtained by decoding the embedded information SC by the decoding unit 37. Equipped with When the detected sound volume exceeds the threshold, the output section outputs the provided information corresponding to the identification information ID obtained by decoding by the decoding section 37, and when the detected sound volume is below the threshold, the output section outputs the provided information corresponding to the identification information ID obtained by decoding by the decoding section 37. A second control unit 32 is provided to output a message. According to this configuration, when the detected sound volume exceeds the threshold value, the provided information corresponding to the identification information ID obtained by decoding by the decoding section 37 is output to the output section. On the other hand, if the detected sound volume is below the threshold, the decoding unit 37 does not perform decoding, and a message indicating that there is no provided information is output to the output unit. In addition to being able to appropriately provide useful information to users, it is possible to reduce errors in which inappropriate information is provided due to erroneous decoding. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be appropriately reduced, and the user of the mobile terminal 15 can be appropriately provided with useful information.

(5) Embedded information SC encoded with the same identification information ID is consecutively embedded multiple times in the acoustic signal AS. Each time the decoding unit 37 succeeds in decoding, it waits without performing decoding for a first waiting time T1 corresponding to the number of consecutive times the embedded information SC is received. According to this configuration, during the predetermined standby time, even if the microphone 31 receives the acoustic signal Sas, at least no decoding is performed, so that the power consumption of the battery BT can be further reduced. In this case, when the volume exceeds the threshold, if the embedded information SC is successfully decoded the first time out of the consecutive multiple times, then the embedded information SC is decoded for the remaining number of times. Since they are decoded into the same identification information ID, by waiting without decoding during that time, it is possible to reduce the number of unnecessary decodings. Note that the predetermined waiting time corresponding to the plurality of times is not limited to the waiting time corresponding to the plurality of times, but may be the waiting time corresponding to the number of times less than the plurality of times by one or two times.

(6) When the number of consecutive times the determination unit 35 determines that the detected volume is less than or equal to the threshold value reaches the set number, the volume detection unit 34 waits without detecting the detected volume during the second standby time T2. According to this configuration, when the number of consecutive times the detected volume is determined to be less than or equal to the threshold value reaches the set number of times, the detected volume is not detected during the second standby time T2. If the embedded information SC cannot be correctly decoded due to noise surrounding the user carrying the mobile terminal 15, not only is the decoding not performed, but also unnecessary detection and determination of the detected sound volume is not performed. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be further reduced.

(7) The second control unit 32 is provided to detect the remaining amount of the battery BT. The second control unit 32 sets the second standby time T2 to be longer when the remaining amount of the battery BT is a second remaining amount, which is less than the first remaining amount, than when the remaining amount of the battery BT is the first remaining amount. Set to time. According to this configuration, the second standby time T2 is set longer as the remaining amount of the battery BT of the mobile terminal 15 is lower, and the power consumption of the battery BT can be reduced.

(8) A spreading method is adopted in which embedded information SC, in which identification information ID is encoded, is spread and embedded in the acoustic signal AS. The decoding unit 37 decodes the embedded information SC into identification information ID. Specifically, the embedded information SC is embedded in the acoustic signal AS using an echo spread method or a spread spectrum method, and the decoding unit 37 performs decoding processing using a spread code. According to this configuration, since the embedded information SC in which the identification information ID is encoded is embedded in the audio signal Sas, it is possible to prevent the original sound such as voice or music included in the audio signal AS from becoming difficult to hear.

(9) The program is executed by a computer included in the acoustic receiving device 30 included in the mobile terminal 15 having the microphone 31 and the battery BT. The acoustic receiving device 30 receives, through the microphone 31, an acoustic signal AS in which embedded information SC in which identification information ID is encoded is embedded. The program includes a computer, a volume detection unit 34 that detects the volume of the audio signal Sas picked up by the microphone 31, a determination unit 35 that determines whether the detected volume detected by the volume detection unit 34 exceeds a threshold, and an audio signal Sas. It functions as an extraction section 36 that extracts embedded information SC from Sas, and a decoding section 37 that decodes embedded information SC into identification information ID. The decoding unit 37 decodes the embedded information SC when the detected volume exceeds the threshold, and does not decode the embedded information SC when the detected volume is below the threshold. By causing a computer to execute the program, power consumption of the battery BT of the mobile terminal 15 can be suppressed by optimizing whether or not to decode the embedded information SC.

(10) The information output method in the acoustic receiving device 30 provided in the mobile terminal 15 having the microphone 31, the output section, and the battery BT includes the following steps. That is, this method includes a volume detection step (S13) in which the volume of the acoustic signal Sas picked up by the microphone 31 is detected, and a determination step (S14) in which it is determined whether the detected volume detected in the volume detection step exceeds a threshold value. ), an extraction step (S15) for extracting the embedded information SC from the acoustic signal Sas, and an output step (S16 to S19). In the output step, when the detected sound volume exceeds the threshold, the embedded information SC is decoded into identification information ID and the provided information corresponding to the identification information ID is outputted to the output section, and when the detected sound volume is below the threshold, The embedded information SC is not decoded and the output unit outputs a message indicating that there is no provided information. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be suppressed by appropriately determining whether or not to decode the embedded information SC.

(Second embodiment)
Next, a second embodiment will be described with reference to FIGS. 6 and 7. The second embodiment has the above-mentioned point that the decoding unit 37 in the audio receiving device 30 determines whether or not to continue the decoding process based on the detection result of the volume detection unit 34 and the decoding process result of the decoding unit 37. This is different from the first embodiment. The other configuration of the acoustic communication system 10 is the same as that of the first embodiment. Hereinafter, a description will be given focusing on the configuration different from the first embodiment.

As shown in FIG. 6, the acoustic receiving device 30 installed in the mobile terminal 15 includes a second control section 32, a receiving section 33, a volume detecting section 34, a determining section 35, and an extracting section 35, as in the first embodiment. It includes a section 36, a decoding section 37, a memory 38, and a display processing section 39.

The extraction unit 36 extracts the embedded information SC from the audio signal Sas collected by the microphone 31, which is an example of a sound collection unit, and inputted via the reception unit 33. The volume detection section 34 inputs the acoustic signal Sas. The volume detection unit 34 detects the volume of the embedded information SC. The determining unit 35 determines whether the detected volume detected by the volume detecting unit 34 exceeds a threshold value. The decoding unit 37 decodes the embedded information SC into identification information ID.

In this embodiment, the volume detecting section 34 detects the volume of the acoustic signal Sas in the same manner as in the first embodiment. Then, the determining unit 35 determines whether the volume of the acoustic signal Sas detected by the volume detecting unit 34 exceeds a threshold value. When the determining unit 35 determines that the volume of the acoustic signal Sas exceeds the threshold, the extracting unit 36 and the decoding unit 37 are activated.

However, even if the volume of the acoustic signal Sas exceeds the threshold value, the embedded information SC may not be embedded in the acoustic signal Sas. Therefore, the determination unit 35 determines the presence or absence of embedded information SC. For example, in the case of the echo diffusion method, it is difficult to determine the presence or absence of embedded information SC unless the decoding unit 37 performs decoding processing. Therefore, the determining unit 35 determines the presence or absence of the embedded information SC based on the decoding result information (decoding processing result) of the decoding unit 37. Further, for example, in the case of the spread spectrum method, the presence or absence of the embedded information SC can be determined from the extraction result information (extraction processing result) of the extraction section 36 even if the decoding section 37 does not perform decoding processing. Therefore, the determination unit 35 determines the presence or absence of embedded information SC based on the extraction result information of the extraction unit 36. In this way, the determining unit 35 determines whether embedded information SC is present based on the decoding result information of the decoding unit 37 or the extraction result information of the extracting unit 36, depending on the embedding method of the embedded information SC.

When the determination unit 35 determines the presence or absence of the embedded information SC based on the decoding result information, the decoding result information may be the identification information ID itself. When the determination unit 35 receives the identification information ID from the decoding unit 37, it determines that there is embedded information. Further, if the decoding section 37 cannot obtain the identification information ID as a result of the decoding process, it sends decoding result information indicating this to the determining section 35 . When the determination unit 35 receives decoding result information indicating that the identification information ID was not obtained from the decoding unit 37, it determines that there is no embedded information. Further, if the decoding result information of the decoding unit 37 is an error indicating a decoding failure in which the embedded information SC could not be decoded into the correct identification information ID, the determining unit 35 determines that embedded information is present. There is a possibility that an error occurred due to decoding failure due to temporary noise, so it is determined that there is embedded information SC. Note that, on the contrary, if the decoding result information of the decoding unit 37 is an error indicating a decoding failure, the determining unit 35 may determine that there is no embedded information.

As a result of the determination, if there is no embedded information SC, the determination unit 35 outputs a determination value of "0". As a result, if there is no embedded information SC, the extraction section 36 and the decoding section 37 are stopped from being activated, or their stopped state is continued. On the other hand, if the embedded information SC is present, the determination unit 35 outputs a determination value of "1". In this case, the extraction section 36 and the decoding section 37 are activated or continue to be activated.

At this time, if the determination unit 35 outputs a determination value of "0", a waiting time is set. In this example, for example, the second waiting time T2 is set. Further, the second waiting time T2 may be set when the number of consecutive determinations that there is no embedded information SC reaches a predetermined number.

Furthermore, even if there is embedded information SC, if the noise around the mobile terminal 15 is large, it may not be possible to decode the embedded information SC. In this case as well, the identification information ID cannot be obtained. Even when decoding fails, the decoding unit 37 sends decoding result information indicating that there is no identification information ID to the determining unit 35. If the determination unit 35 determines that decoding has failed based on the decoding result information and the number of consecutive decoding failures reaches a set number, it outputs a determination value of "0" and sets a second waiting time T2. You may. This type of noise surrounding the mobile terminal 15 includes the sound of trains and station announcements when the user is at a station, traffic noise when the user is near a road with a lot of traffic such as cars, etc. Examples include conversations with people around the user, such as when the user is in a crowd.

In this way, in this embodiment, since the presence or absence of the embedded information SC is determined, it is not limited to the case where the embedded information SC is not embedded in the acoustic signal Sas. It is possible to appropriately determine whether the volume is low. However, in order to determine the presence or absence of the embedded information SC, it is necessary to activate the extraction section 36 and the decoding section 37. Further, in order to detect the volume from the signal component of the embedded information SC, it is necessary to activate the extraction unit 36. Therefore, the power consumption required for the extraction section 36 and the decoding section 37 tends to be larger than that in the first embodiment. However, in the first embodiment, when the volume of the audio signal Sas exceeds the threshold, the decoding unit 37 continues the decoding process even if the embedded information SC is not embedded in the audio signal Sas. In contrast, in the present embodiment, even if the volume of the acoustic signal Sas exceeds the threshold, if the embedded information SC is not embedded in the acoustic signal Sas, the extraction unit 36 and the decoding unit 37 are stopped from starting. be done. Therefore, overall, the power consumption of the battery BT can be suppressed more than in the first embodiment. Note that if the presence or absence of the embedded information SC can be determined based on the embedded information SC extracted by the extraction unit 36, the extraction result information obtained by the extraction process performed by the extraction unit 36 may be sent to the determination unit 35. In this case, if the determination unit 35 determines that the embedded information SC is embedded in the acoustic signal Sas based on the extraction result information sent from the extraction unit 36, it activates the decoding unit 37. On the other hand, if the determining unit 35 determines that the embedded information SC is not embedded in the acoustic signal Sas based on the extraction result information sent from the extracting unit 36, the determining unit 35 stops the activation of the decoding unit 37 or stops the decoding unit 37. continue.

Next, the operation of the acoustic receiving device 30 will be explained.
Hereinafter, with reference to FIG. 7, the operation of the acoustic receiving device 30, which is driven by the CPU of the mobile terminal 15 executing a program, will be described. Note that the program corresponds to an application that is installed in the mobile terminal 15 and causes the CPU (computer) to function as each of the units 32 to 39 configuring the acoustic receiving device 30. Further, in FIG. 7, steps S11 and S12 that are common to the first embodiment are omitted. Below, processing that is different from the first embodiment will be mainly explained. Other processes are basically the same as those in the first embodiment.

The user operates the operation unit 16 of the mobile terminal 15 to activate the acoustic receiving device 30. Upon this activation, the CPU executes the program of the acoustic signal reception processing routine shown in FIG.
The processing in steps S11 to S16 is the same as in the first embodiment. That is, upon receiving the acoustic signal Sas (affirmative determination in step S11), the CPU determines whether or not the standby time has elapsed (step S12). That is, if either one of the first standby time T1 and the second standby time T2 has not elapsed (negative determination in step S12), the CPU waits until the standby time has elapsed. On the other hand, if both the first standby time T1 and the second standby time T2 have elapsed, the process advances to step S13.

The CPU calculates the average volume (step S13). This process is performed by the volume detection section 34. The volume detection unit 34 samples the volume at N points per unit time of the audio signal Sas, integrates the volume at the N points, and divides the total value by N, thereby calculating the average volume of the audio signal Sas. This step corresponds to an example of the volume detection step.

Then, the CPU determines whether the average volume exceeds the threshold (step S14). This determination is made by the determination unit 35. If the average volume exceeds the threshold, the process advances to step S15, and if the average volume does not exceed the threshold, the process advances to step S18. Here, if the average sound volume exceeds the threshold value, the determination section 35 outputs a determination value of "1", so the extraction section 36 and the decoding section 37 are activated. On the other hand, if the average volume does not exceed the threshold, the determination unit 35 outputs a determination value of “0”, so the extraction unit 36 and the decoding unit 37 are not activated or stop activation. In addition, in this embodiment, the process of this step S14 corresponds to an example of a determination step.

Further, the CPU extracts embedded information SC (step S15). This process is performed by the extraction unit 36. The extraction unit 36 extracts embedded information SC from the audio signal Sas input from the reception unit 33. The embedded information SC is extracted using an extraction method depending on the spreading method employed, such as an echo diffusion method or a spread spectrum method. Note that the process in step S15 corresponds to an example of an extraction step.

The CPU executes decoding processing (step S16). This process is performed by the decoding section 37. The decoding unit 37 decodes the embedded information SC into the identification information ID before encoding by cross-correlating the embedded information SC with the same PN sequence as the PN sequence spread by the embedding unit 28. do. The decoding unit 37 sends the decoding result information to the determining unit 35 and also sends the decoded identification information ID to the second control unit 32.

In the next step S21, the CPU determines whether or not there is identification information ID. This process is performed by the determination unit 35. That is, the determination unit 35 determines the presence or absence of the embedded information SC by determining the presence or absence of the identification information ID decoded by the decoding unit 37. That is, the presence or absence of embedded information SC in the acoustic signal AS is determined. If the CPU has the identification information ID, the process proceeds to step S17, and if there is no identification information ID, the process proceeds to step S18. In the echo diffusion method, the presence or absence of embedded information SC cannot be determined without decoding processing, so both the extraction processing by the extraction section 36 and the decoding processing by the decoding section 37 are performed. For example, in the spread spectrum method, if the presence or absence of the embedded information SC can be determined from the acoustic signal AS without decoding, then the extraction process by the extraction unit 36 may be performed without decoding. This can be done by performing the minimum amount of processing necessary to determine the presence or absence of the embedded information SC, depending on the embedding method employed. Alternatively, the presence or absence of the embedded information SC may be determined by using another method without activating either the extraction unit 36 or the decoding unit 37.

The processing in steps S17 to S19 is similar to that in the first embodiment shown in FIG. That is, in step S17, the CPU causes the output unit to output the provision information corresponding to the identification information ID. The second control unit 32 obtains the provision information corresponding to the identification information ID by referring to the reference table DT (see FIG. 6) stored in the memory 38 based on the identification information ID. Then, the second control unit 32 displays the provided information on the display unit 17 via the display processing unit 39, and causes the sound output processing unit to display the provided information on the headphones or earphones connected to the earphone jack, or the speaker (any one) of the mobile terminal 15. (not shown) to emit provided information.

In step S21, if there is no embedded information SC, the CPU moves to step S18. In step S18, the CPU sets a standby time. In other words, even if the volume of the acoustic signal Sas exceeds the threshold, if it is determined that the embedded information SC is not embedded in the acoustic signal Sas, the determination unit 35 outputs the determination value "0". , the extraction section 36 and the decoding section 37 are stopped from being activated, or are kept in a stopped state. Then, the CPU sets a standby time for continuing the stopped state. Here, the CPU sets the second waiting time T2. Then, in step S19, the CPU outputs to the output section that there is no identification information ID.

As described above in detail, according to the second embodiment, in addition to the effects (4) to (8) of the first embodiment, the following effects can also be obtained.
(11) The determining unit 35 further determines the presence or absence of embedded information SC in the acoustic signal Sas, and if it is determined that there is no embedded information SC even if the detected sound volume exceeds the threshold, the decoding unit 37 decodes No processing is performed. According to this configuration, the determination unit 35 determines the presence or absence of embedded information SC in the acoustic signal Sas. If there is no embedded information SC, no decoding process will be performed even if the detected volume exceeds the threshold. That is, if the embedded information SC is not embedded in the acoustic signal Sas, no wasteful decoding processing is performed. Therefore, power consumption of the acoustic receiving device 30 can be reduced. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be suppressed by optimizing whether or not to perform the decoding process.

(12) The determination unit 35 determines the presence or absence of embedded information SC based on the extraction processing result by the extraction unit 36 or the decoding processing result by the decoding unit 37. According to this configuration, there is no need to separately provide a processing unit for detecting the presence or absence of embedded information SC, and the presence or absence of embedded information SC can be accurately determined. Therefore, the problem of not performing decoding even though there is embedded information SC, or conversely, performing decoding even though there is no embedded information SC is reduced. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be appropriately reduced.

(13) If it is determined that there is no embedded information SC even if the detected volume exceeds the threshold, the extraction unit 36 waits without performing the extraction process. Therefore, if it is determined that there is no embedded information even if the detected sound volume exceeds the threshold, the decoding section 37 waits without performing the decoding process, and the extracting section 36 waits without performing the extraction process. Therefore, the power consumption of the battery BT of the mobile terminal 15 can be further reduced.

The embodiment is not limited to the above, and may be modified in the following manner.
- In each embodiment, the volume determination including volume detection by the volume detection unit 34 and determination by the determination unit 35 is performed during the initial startup period when the audio signal AS is first received after the user activates the audio receiving device 30. It may be executed only if Furthermore, in addition to the initial startup period of the acoustic receiving device 30, the volume is not determined in real time thereafter, but is determined regularly or irregularly at predetermined time intervals that are sufficiently longer than the execution cycle of the CPU. Good too. The time interval is, for example, a time in the range of 10 seconds to 10 minutes.

- In each embodiment, the volume detection by the volume detection unit 34 and the determination by the determination unit 35 are performed only during the initial startup period when the audio signal AS is first received after the user activates the audio receiving device 30. You can.

- In each embodiment, the second control unit 32 detects the remaining amount of the battery BT, and when the remaining amount of the battery BT becomes equal to or less than the remaining amount threshold, the second control unit 32 executes the acoustic signal reception processing routine shown in FIGS. 5 and 7. It may also be configured to execute. In this case, the volume detecting section 34, the determining section 35, the extracting section 36, and the decoding section 37 may be activated at all times while the remaining amount of the battery BT exceeds the remaining amount threshold. The remaining capacity threshold of the battery BT is, for example, 50%. Note that the remaining amount threshold is not limited to 50%, but may be 70% or 30%.

- In each embodiment, the first standby time T1 may be set as follows. The second control unit 32 uses a counter to count how many times the same embedded information SC has succeeded out of n consecutive times, and if it has succeeded the pth time, it sets the first waiting time T1 as T1=(n -p)t may be set.

- In each of the above embodiments, the first standby time T1 is set, but the setting of the first standby time T1 may be omitted.
- In each of the above embodiments, the second standby time T2 is set, but the setting of the second standby time T2 may be omitted. In addition, the second standby time T2 is set when the number of consecutive times the detected sound volume is below the threshold reaches the set number, but if the detected sound volume is below the threshold even once, the second standby time T2 cannot be set. good.

- In the second embodiment, the determination unit 35 may determine the presence or absence of the embedded information SC based on the extraction result information (extraction processing result) of the extraction unit 36. For example, in the case of the spread spectrum method, the signal component of the embedded information SC may be extracted from the acoustic signal Sas, and the presence or absence of the embedded information SC may be determined based on this signal component. According to this configuration, the activation of the decoding section 37 can be stopped when the determining section 35 determines the presence or absence of the embedded information SC, so that the power consumption of the battery BT can be further reduced.

- In the second embodiment, the determination unit 35 may only determine the presence or absence of the embedded information SC among the determination of the volume of the audio signal and the determination of the presence or absence of the embedded information SC. In this case, if there is no embedded information SC, the decoding unit 37 does not perform decoding processing, so power consumption can be suppressed.

- The acoustic receiving device 30 is not limited to the configuration provided in the mobile terminal 15. The acoustic receiving device 30 may be included in a device that is not portable. In this case, the non-portable device may not include a battery and may be configured to receive power from a commercial power source through a cable. Even if the device does not include a battery, the power consumption of the acoustic receiving device 30 can be suppressed.

・Masking using audio and digital watermarking technology is not limited to forward masking, but may also be backward masking.
- The audio digital watermarking method is not limited to the echo diffusion method or the spread spectrum method, but other diffusion methods may also be used. As long as the acoustic receiving device 30 includes the decoding section 37 that decodes a spreading code, a periodic phase modulation method, a phase multiplexing method, an amplitude modulation method, etc. may be used, for example. Further, the spread spectrum method may be a direct spread method or a frequency hopping method.

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

DESCRIPTION OF SYMBOLS 10... Acoustic communication system 11... Broadcasting device 12... Speaker as an example of a sound emitting part 15... Mobile terminal 16... Operation part 17... Display part as an example of an output part 20... Sound transmitting device 21... First input part 22... Second input section 23... First control section 26... Spreading code generator 27... Encoding section 28... Embedding section 29... Transmitting section 30... Sound receiving device 31... Microphone as an example of a sound collection section 32... An example of the control section 33...Receiving unit 34...Sound volume detection unit 35...Determination unit 36...Extraction unit 37...Decoding unit 38...Memory 39...Display processing unit BT...Battery DT...Reference table AS...Acoustic signal Sas...Acoustic signal OS...Original sound signal SC...Embedded information ID...Identification information T1...First standby time T2...Second standby time

Claims (20)

An acoustic receiving device that collects an acoustic signal in which embedded information is embedded, using a sound collecting section,
a volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit;
a determination unit that determines whether the detected volume detected by the volume detection unit exceeds a threshold;
an extraction unit that performs an extraction process to extract the embedded information from the acoustic signal;
a decoding unit that performs decoding processing to decode the embedded information into identification information,
The decoding unit performs the decoding process when the detected volume exceeds the threshold, and does not perform the decoding when the detected volume is below the threshold;
The determination unit further determines the presence or absence of the embedded information in the acoustic signal,
If it is determined that there is no embedded information even if the detected sound volume exceeds the threshold, the extraction unit performs the extraction process for a predetermined waiting time from the time when it is determined that there is no embedded information. The acoustic receiving device waits without performing extraction processing, and restarts the extraction processing when the waiting time elapses . An acoustic receiving device that collects an acoustic signal in which embedded information is embedded, using a sound collecting section,
a volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit;
a determination unit that determines whether the detected volume detected by the volume detection unit exceeds a threshold;
an extraction unit that performs an extraction process to extract the embedded information from the acoustic signal;
a decoding unit that performs decoding processing to decode the embedded information into identification information ;
It is equipped with a control section ,
The decoding unit performs the decoding process when the detected volume exceeds the threshold, and does not perform the decoding when the detected volume is below the threshold;
The control unit causes an output unit to output provided information corresponding to the identification information obtained by decoding by the decoding unit when the detected volume exceeds the threshold, and when the detected volume is below the threshold, , an acoustic receiving device that causes the output unit to output a message indicating that there is no information to be provided . An acoustic receiving device that collects an acoustic signal in which embedded information is embedded, using a sound collecting section,
a volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit;
a determination unit that determines whether the detected volume detected by the volume detection unit exceeds a threshold;
an extraction unit that performs an extraction process to extract the embedded information from the acoustic signal;
a decoding unit that performs decoding processing to decode the embedded information into identification information,
The embedded information in which the same identification information is encoded is consecutively embedded in the acoustic signal a plurality of times,
The decoding unit performs the decoding process when the detected volume exceeds the threshold, and does not perform the decoding when the detected volume is below the threshold;
When the decoding process is performed, the audio receiving device waits without performing decoding for a first standby time corresponding to the plurality of consecutive times of the embedded information each time the decoding is successful. An acoustic receiving device that collects an acoustic signal in which embedded information is embedded, using a sound collecting section,
a volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit;
a determination unit that determines whether the detected volume detected by the volume detection unit exceeds a threshold;
an extraction unit that performs an extraction process to extract the embedded information from the acoustic signal;
a decoding unit that performs decoding processing to decode the embedded information into identification information,
The decoding unit performs the decoding process when the detected volume exceeds the threshold, and does not perform the decoding when the detected volume is below the threshold;
When the number of consecutive times the determination unit determines that the detected volume is less than or equal to the threshold value reaches a set number, the volume detection unit performs sound reception in which the volume detection unit waits without detecting the detected volume during a second standby time. Device. The volume detection unit calculates an average volume per unit time of the acoustic signal,
The acoustic receiving device according to any one of claims 1 to 4, wherein the determination unit makes the determination by comparing the average volume and the threshold value. The extraction unit performs the extraction process when the detected volume exceeds the threshold, and does not perform the extraction process when the detected volume is equal to or less than the threshold. The acoustic receiving device described in . The determination unit further determines the presence or absence of the embedded information in the acoustic signal,
The decoding unit does not perform the decoding process when it is determined that the embedded information is not present even if the detected sound volume exceeds the threshold value . Receiving device. 8. The acoustic receiving apparatus according to claim 1 , wherein the determination section determines whether or not the embedded information is present based on the extraction processing result by the extraction section or the decoding processing result by the decoding section. When the detected sound volume exceeds the threshold, the output unit outputs provided information corresponding to the identification information obtained by decoding by the decoding unit, and when the detected sound volume is below the threshold, the output unit The acoustic receiving device according to any one of claims 1 , 3, and 4, further comprising a control unit that outputs a message indicating that there is no provided information. The embedded information in which the same identification information is encoded is consecutively embedded in the acoustic signal a plurality of times,
Each time the decoding unit succeeds in decoding, the decoding unit waits without performing decoding for a first waiting time corresponding to the plurality of consecutive times of the embedded information. The acoustic receiving device according to any one of the items. When the number of consecutive times in which the detected volume is determined to be less than or equal to the threshold value by the determining unit reaches a set number of times, the volume detecting unit waits without detecting the detected volume during a second standby time. The acoustic receiving device according to any one of claims 1 to 3 . provided in a mobile terminal having a battery,
comprising a control unit that detects the remaining amount of the battery,
The control unit sets the second standby time to be longer when the battery has a second remaining capacity that is lower than the first remaining capacity than when the battery has a first remaining capacity. The acoustic receiving device according to claim 4, wherein the acoustic receiving device is set to . A program that is executed by a computer included in an acoustic receiving device that collects an acoustic signal in which embedded information is embedded in a sound collecting section,
computer,
a volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit;
a determination unit that determines whether the detected volume detected by the volume detection unit exceeds a threshold , and determines whether or not the embedded information is present in the audio signal ;
an extraction unit that performs an extraction process to extract the embedded information from the acoustic signal, and if it is determined that the embedded information does not exist even if the detected sound volume exceeds the threshold value, the embedded information is not present; The extraction unit waits without performing the extraction process for a predetermined waiting time from when it is determined that the extraction process is resumed after the waiting time has elapsed;
When the detected volume exceeds the threshold, a decoding process is performed to decode the embedded information into identification information, and when the detected volume is below the threshold, the unit functions as a decoding unit that does not perform the decoding process. program for. A program that is executed by a computer included in an acoustic receiving device that collects an acoustic signal in which embedded information is embedded in a sound collecting section,
computer,
a volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit;
a determination unit that determines whether the detected volume detected by the volume detection unit exceeds a threshold;
an extraction unit that performs an extraction process to extract the embedded information from the acoustic signal;
a decoding unit that performs a decoding process to decode the embedded information into identification information when the detected volume exceeds the threshold, and does not perform the decoding process when the detected volume is below the threshold;
When the detected sound volume exceeds the threshold, the output unit outputs provided information corresponding to the identification information obtained by decoding by the decoding unit, and when the detected sound volume is below the threshold, the output unit A program to function as a control unit that outputs a message indicating that there is no provided information . A program that is executed by a computer included in an acoustic receiving device that collects an acoustic signal in which embedded information is embedded in a sound collecting section,
computer,
a volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit;
a determination unit that determines whether the detected volume detected by the volume detection unit exceeds a threshold;
an extraction unit that performs an extraction process to extract the embedded information from the acoustic signal;
A decoding unit that performs a decoding process to decode the embedded information into identification information when the detected volume exceeds the threshold, and does not perform the decoding process when the detected volume is below the threshold, When the decoding process is performed, each time the decoding is successful, a first waiting time corresponding to the plurality of times the embedded information in which the same identification information is encoded in the acoustic signal is consecutively embedded. A program for functioning as the decoding section that waits without performing decoding during this period . A program that is executed by a computer included in an acoustic receiving device that collects an acoustic signal in which embedded information is embedded in a sound collecting section,
computer,
a volume detection unit that detects the volume of the acoustic signal collected by the sound collection unit;
a determination unit that determines whether the detected volume detected by the volume detection unit exceeds a threshold;
an extraction unit that performs an extraction process to extract the embedded information from the acoustic signal;
a decoding unit that performs a decoding process to decode the embedded information into identification information when the detected volume exceeds the threshold, and does not perform the decoding process when the detected volume is below the threshold;
When the number of consecutive times in which the detection volume is determined to be less than or equal to the threshold by the determination unit reaches a set number of times, the volume detection unit functions as the volume detection unit that waits without detecting the detection volume during a second standby time. program for. An acoustic signal receiving method in an acoustic receiving device in which an acoustic signal in which embedded information is embedded is collected by a sound collecting section, the method comprising:
a volume detection step of detecting the volume of the acoustic signal collected by the sound collection unit;
a first determination step of determining whether the detected volume detected in the volume detection step exceeds a threshold;
an extraction step of performing an extraction process to extract the embedded information from the acoustic signal;
a decoding step of performing a decoding process of decoding the embedded information into identification information if the detected volume exceeds the threshold, and not performing the decoding process if the detected volume is below the threshold ;
a second determination step of determining the presence or absence of the embedded information in the acoustic signal;
In the extraction step, if it is determined that there is no embedded information even if the detected volume exceeds the threshold, the extraction process is performed for a predetermined waiting time from the time when it is determined that there is no embedded information. An acoustic signal receiving method in an acoustic receiving apparatus , wherein the acoustic signal receiving apparatus waits without performing extraction processing, and restarts the extraction processing when the waiting time elapses . An acoustic signal receiving method in an acoustic receiving device in which an acoustic signal in which embedded information is embedded is collected by a sound collecting section, the method comprising:
a volume detection step of detecting the volume of the acoustic signal collected by the sound collection unit;
a determination step of determining whether the detected volume detected in the volume detection step exceeds a threshold;
an extraction step of performing an extraction process to extract the embedded information from the acoustic signal;
a decoding step of performing a decoding process of decoding the embedded information into identification information if the detected volume exceeds the threshold, and not performing the decoding process if the detected volume is below the threshold ;
When the detected sound volume exceeds the threshold, the output section outputs provided information corresponding to the identification information obtained by decoding by the decoding process, and when the detected sound volume is below the threshold, the output section An acoustic signal receiving method in an acoustic receiving device, comprising : outputting a message indicating that there is no provided information . An acoustic signal receiving method in an acoustic receiving device in which an acoustic signal in which embedded information is embedded is collected by a sound collecting section, the method comprising:
a volume detection step of detecting the volume of the acoustic signal collected by the sound collection unit;
a determination step of determining whether the detected volume detected in the volume detection step exceeds a threshold;
an extraction step of performing an extraction process to extract the embedded information from the acoustic signal;
a decoding step of performing a decoding process of decoding the embedded information into identification information when the detected volume exceeds the threshold, and not performing the decoding process when the detected volume is below the threshold ;
The embedded information in which the same identification information is encoded is consecutively embedded in the acoustic signal a plurality of times,
In the decoding step, when the decoding process is performed, the acoustic receiving device waits without performing decoding for a first standby time corresponding to the plurality of successive times of the embedded information each time the decoding is successful. Acoustic signal reception method. An acoustic signal receiving method in an acoustic receiving device in which an acoustic signal in which embedded information is embedded is collected by a sound collecting section, the method comprising:
a volume detection step of detecting the volume of the acoustic signal collected by the sound collection unit;
a determination step of determining whether the detected volume detected in the volume detection step exceeds a threshold;
an extraction step of performing an extraction process to extract the embedded information from the acoustic signal;
a decoding step of performing a decoding process of decoding the embedded information into identification information when the detected volume exceeds the threshold, and not performing the decoding process when the detected volume is below the threshold ;
In the sound volume detection step, when the number of consecutive times the detected sound volume is determined to be equal to or less than the threshold value reaches a set number of times, the sound receiving device waits without detecting the detected sound volume for a second waiting time, and the sound signal is How to receive.