JP6256342B2 - DTMF signal erasing device, DTMF signal erasing method, and DTMF signal erasing program - Google Patents

Description

  The present invention relates to a DTMF signal erasing device, and more particularly to a DTMF signal erasing device that reduces processing load when DTMF signals are erased.

  A DTMF (Dual-Tone Multi-Frequency) signal is a signal generated when a push button provided in the telephone is pressed. As a communication method of the DTMF signal, there are an in-band method in which the DTMF signal is communicated as an audio signal and an out-of-band method in which the DTMF signal is communicated as a control signal.

  The specification of the DTMF signal used in the case of the in-band system is defined in ITU-T (International Telecommunication Union Telecommunication Standardization Sector) Recommendation Q.24. This specification selects one frequency from the low group frequencies 697Hz, 770Hz, 852Hz, 941Hz and one frequency from the high group frequencies 1209Hz, 1336Hz, 1447Hz, 1644Hz and synthesizes a sine wave of those frequencies. Stipulates that 16 types of signals are represented.

  FIG. 19 shows a DTMF signal corresponding to a combination of a low group frequency and a high group frequency. For example, a combination of 697 Hz and 1209 Hz sine waves represents “1”, and a combination of 941 Hz and 1477 Hz represents “#”.

  In addition, the specification of the DTMF signal used in the case of the out-of-band method is defined in IETF (Internet Engineering Task Force) RFC (Request for Comments) 2833.

  The DTMF signal is used in a teleconference system for command transmission from a conference participation terminal (telephone) to a conference server, such as an acquisition request for the number of conference participation terminals, an individual mute request, and a conference extension request.

  An example of a telephone conference system related to the present invention is described in Patent Document 1. The teleconference system described in Patent Document 1 adjusts the level of the audio signal received from each terminal, synthesizes the audio signal received from other than the distribution destination terminal, and distributes it to the distribution destination terminal. Yes. For example, when terminals A, B, C, and D are having a telephone conference, the telephone conference system distributes to terminal A a synthesized voice signal of terminals B, C, and D. Here, when terminal D transmits a command using an in-band DTMF signal to the telephone conference server that constitutes the telephone conference system, this DTMF signal is transmitted to terminals A, B, and C. become. However, this signal is unnecessary information for each terminal A, B and C. Since these terminals may malfunction due to this signal, it is necessary to delete this signal at the teleconference server.

  An example of an in-band DTMF signal erasing method related to the present invention is described in Patent Document 2. The technique of Patent Document 2 is intended for a ringback tone and a busy tone, but the DTMF signal can be similarly deleted. In the DTMF signal erasing method described in Patent Document 2, the DTMF signal is erased by a band-pass filter that passes frequencies other than those used in the DTMF signal.

  Further, Patent Document 3 specifies a voiceless section, estimates the noise characteristics of the voiceless section from a part or the whole of the voice signal wave, and determines whether the voice section and An example of a technique for identifying a speech section is described.

  Patent Document 4 describes an example of a DTMF signal erasing method technique for erasing a DTMF signal included in an audio signal.

JP 2007-096555 JP 2005-143003 JP Japanese Patent Publication No. 1-1014599 JP 2007-049762

  The first problem in the related art is that if the DTMF signal is deleted, the number of conferences that can be simultaneously processed by the telephone conference server is reduced.

  The reason is that the amount of calculation of the band-pass filter processing performed for erasing the DTMF signal is large.

  A main object of the present invention is to provide a DTMF signal erasing signal device, a DTMF signal erasing method, and a program for increasing the number of conferences that can be processed simultaneously by a telephone conference server.

  A DTMF signal erasing device according to an aspect of the present invention is a processing method determination unit that determines whether a signal other than a DTMF signal is included in an audio signal based on a comparison between the signal level of the audio signal and a threshold value. And a frequency component erasure unit that outputs a first signal in which the frequency component of the DTMF signal is eliminated from the audio signal when a signal other than the DTMF signal is included, and a signal other than the DTMF signal is included. If not, a signal replacement unit that outputs a second signal in which the audio signal is replaced with another signal, and a sound determination unit in which the frequency component erasure unit performs the sound determination of the first signal. The processing method determination unit sets the threshold based on the result of the sound determination of the sound determination unit and the signal level of the audio signal.

  The telephone conference server device according to an aspect of the present invention is a processing method determination unit that determines whether a signal other than a DTMF signal is included in a voice signal based on a comparison between a signal level of the voice signal and a threshold value. And a frequency component erasure unit that outputs a first signal in which the frequency component of the DTMF signal is eliminated from the audio signal when a signal other than the DTMF signal is included, and a signal other than the DTMF signal is included. If not, a signal replacement unit that outputs a second signal in which the audio signal is replaced with another signal, and a sound determination unit in which the frequency component erasure unit performs the sound determination of the first signal. The processing method determination unit sets the threshold based on the sound determination result of the sound determination unit and the signal level of the sound signal; and a DTMF signal erasing device; Received audio signal receiver and received audio DTMF signal included in the signal, performs processing corresponding to the DTMF signal, and outputs the audio signal and the DTMF signal to the DTMF signal erasing device, and the DTMF signal erasing device An audio signal synthesizer that synthesizes the audio signal from which the DTMF signal has been deleted, and an audio signal transmitter that transmits the synthesized audio signal to the terminal.

  A DTMF signal conversion device according to an aspect of the present invention is a processing method determination unit that determines whether a signal other than a DTMF signal is included in an audio signal based on a comparison between the signal level of the audio signal and a threshold value. And a frequency component erasure unit that outputs a first signal in which the frequency component of the DTMF signal is eliminated from the audio signal when a signal other than the DTMF signal is included, and a signal other than the DTMF signal is included. If not, a signal replacement unit that outputs a second signal in which the audio signal is replaced with another signal, and a sound determination unit in which the frequency component erasure unit performs the sound determination of the first signal. The processing method determination unit receives the audio signal, and a DTMF signal erasing device that sets the threshold based on a result of the audio determination of the audio determination unit and the signal level of the audio signal Included in the audio signal receiver and the received audio signal A DTMF signal detection unit that detects a DTMF signal and outputs the audio signal and the DTMF signal to a DTMF signal erasing device; and an audio signal transmission unit that transmits the audio signal from which the DTMF signal erasing device has deleted the DTMF signal; A control signal transmission unit for transmitting the DTMF signal.

  The DTMF signal erasing method according to one aspect of the present invention determines whether a signal other than the DTMF signal is included in the audio signal based on a comparison between the signal level of the audio signal and a threshold value, and other than the DTMF signal. When the signal is included, the first signal from which the frequency component of the DTMF signal is deleted from the audio signal is output, and when the signal other than the DTMF signal is not included, the audio signal is The second signal replaced with the signal is output, the sound determination of the first signal is performed, and the threshold value is set based on the result of the sound determination and the signal level of the audio signal.

  The DTMF signal erasing program according to one embodiment of the present invention determines whether or not a sound signal includes a signal other than a DTMF (Dual-Tone Multi-Frequency) signal in the computer, the signal level of the sound signal, and a threshold value. A process based on the comparison, a process for outputting the first signal in which the frequency component of the DTMF signal is deleted from the audio signal when a signal other than the DTMF signal is included, and a process other than the DTMF signal. When a signal is not included, a process of outputting a second signal obtained by replacing the audio signal with another signal, a process of performing a sound determination of the first signal, and a result of the sound determination And a process of setting the threshold based on the signal level of the audio signal.

  The object of the present invention is also achieved by a computer-readable storage medium storing the above program.

  The first effect of the present invention is to increase the number of conferences that can be processed simultaneously by the telephone conference server.

FIG. 1 is a block diagram showing a configuration of a DTMF signal erasing apparatus 1 according to the first embodiment of the present invention. FIG. 2 is a diagram showing a hardware configuration of the DTMF signal erasing device 1 and its peripheral devices according to the first embodiment of the present invention. FIG. 3 is a flowchart showing the operation of the DTMF signal erasing apparatus 1 according to the first embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of the DTMF signal erasing apparatus 2 according to the second embodiment of the present invention. FIG. 5 is a diagram illustrating an example of information stored in the signal information storage unit 28. As illustrated in FIG. FIG. 6 is a flowchart showing the operation of the DTMF signal erasing apparatus 2 in the second embodiment of the present invention. FIG. 7 is a graph showing the relationship between the signal level and the threshold value. FIG. 8 is a block diagram showing an example of the configuration of the telephone conference server device 40 according to the fourth embodiment of the present invention. FIG. 9 is a block diagram showing another example of the configuration of the telephone conference server device 40 according to the fourth embodiment of the present invention. FIG. 10 is a diagram illustrating another example of information stored in the signal information storage unit. FIG. 11 is a block diagram showing an example of the configuration of the DTMF signal conversion apparatus 50 in the fifth embodiment of the present invention. FIG. 12 is a diagram illustrating an example of information stored in the signal information storage unit 28 by the processing method determination unit 22. FIG. 13 is a diagram illustrating an example of information stored in the signal information storage unit 28 by the sound determination unit 25. As illustrated in FIG. FIG. 14 is an example of information stored in the signal information storage unit 28. FIG. 15 is an example of information stored in the signal information storage unit 28. FIG. 16 is a diagram illustrating an example of information stored in the signal information storage unit 28 when the processing method determination unit 22 updates the threshold value to 80.0. FIG. 17 is a diagram illustrating an example of information stored in the signal information storage unit 28. As illustrated in FIG. FIG. 18 is a diagram illustrating an example of information stored in the signal information storage unit 28 by the process determination method determination unit 22. FIG. 19 shows a DTMF signal corresponding to a combination of a low group frequency and a high group frequency.

  Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Note that, in each embodiment described in each drawing and specification, the same reference numerals are given to components having the same function.

<First Embodiment>
FIG. 1 is a block diagram showing a configuration of a DTMF signal erasing apparatus 1 according to the first embodiment of the present invention.

  Referring to FIG. 1, the DTMF signal erasing apparatus 1 according to the first embodiment of the present invention includes a processing method determining unit 12, a frequency component erasing unit 14, a signal replacing unit 16, a sound determining unit 15, Is provided.

  The DTMF signal erasing apparatus 1 in the first embodiment determines whether or not a signal other than the DTMF signal is included in the audio signal based on the comparison between the signal level of the audio signal and a threshold value. When the DTMF signal erasing apparatus 1 determines that a signal other than the DTMF signal is not included, the DTMF signal erasing apparatus 1 performs processing for replacing the above-described audio signal with another signal.

  That is, the DTMF signal erasing apparatus 1 according to the first embodiment, when the signal level of the audio signal is compared with the threshold value and satisfies a predetermined condition, The process of replacing with the above signal is performed. Therefore, the DTMF signal elimination device 1 can reduce the number of computations and the amount of computation with a large amount of computation such as a band-pass filter required for the DTMF signal elimination processing, thus increasing the number of conferences that can be processed simultaneously by the teleconference server. It becomes possible to make it.

  Hereinafter, each component provided in the DTMF signal erasing apparatus 1 according to the first embodiment will be described.

=== Processing Method Determination Unit 12 ===
The processing method determination unit 12 receives an audio signal, and compares whether the audio signal contains a signal other than a DTMF (Dual-Tone Multi-Frequency) signal by comparing the signal level of the audio signal with a threshold value. Judgment based on.

  For example, the processing method determination unit 12 may determine whether a signal other than the DTMF signal is included in the audio signal based on the magnitude relationship between the signal level of the received audio signal and the threshold value. In this case, the processing method determination unit 12 may determine that the audio signal includes a signal other than the DTMF signal when the signal level of the received audio signal is greater than the threshold value. Further, the processing method determination unit 12 may determine that a signal other than the DTMF signal is not included in the audio signal when the signal level of the received audio signal is equal to or lower than the threshold value.

  When it is determined that the received audio signal includes a signal other than the DTMF signal, the processing method determination unit 12 determines to delete the frequency component of the DTMF signal from the audio signal as the audio signal processing method. Then, the processing method determination unit 12 passes the audio signal to a frequency component elimination unit 14 described later.

  On the other hand, when it is determined that the received audio signal does not include a signal other than the DTMF signal, the processing method determination unit 12 determines to replace the audio signal with another signal as the audio signal processing method. Then, the processing method determination unit 12 passes the audio signal to the signal replacement unit 16 described later.

  Further, the processing method determination unit 12 sets the above-described threshold based on the signal level of the received audio signal and the sound determination result determined by the sound determination unit 15 described later. This method will be described later.

=== Frequency Component Erasing Unit 14 ===
The frequency component erasure unit 14 receives the audio signal from the processing method determination unit 12, and erases the frequency component of the DTMF signal from the received audio signal.

  For example, the frequency component erasure unit 14 may receive the type of the DTMF signal included in the audio signal together with the received audio signal, and erase the frequency component corresponding to the received type from the audio signal.

  The frequency component elimination unit 14 outputs a first signal that is an audio signal from which the frequency component of the DTMF signal has been eliminated, and passes the first signal to the sound determination unit 15 described later.

=== Sound determination unit 15 ===
The sound determination unit 15 determines whether or not the first signal received from the frequency component elimination unit 14 is sound. A specific method of sound determination in the sound determination unit 15 will be described later.

  The sound determination unit 15 passes the result of sound determination to the processing method determination unit 12.

=== Signal Replacement Unit 16 ===
The signal replacement unit 16 receives the audio signal from the processing method determination unit 12, and outputs a second signal that is a signal obtained by replacing the received audio signal with another signal.

  The other signal specifically includes a silence signal or a noise signal, but the other signal is not limited to the signal of these forms.

  Specifically, the signal replacement unit 16 specifies the length of the received audio signal and generates another signal corresponding to the length. Then, the signal replacement unit 16 outputs a second signal in which the generated signal is replaced with the received audio signal.

  FIG. 2 is a diagram showing a hardware configuration of the DTMF signal erasing device 1 and its peripheral devices according to the first embodiment of the present invention. As shown in FIG. 2, the DTMF signal erasing device 1 includes a CPU (Central Processing Unit) 191, a communication I / F 192 (communication interface 192) for network connection, a memory 193, and a storage device such as a hard disk for storing programs. Includes 194. The DTMF signal erasing device 1 is connected to an input device 195 and an output device 196 via a bus 197.

  The CPU 191 operates the operating system to control the entire DTMF signal erasing apparatus 1 according to the first embodiment of the present invention. Further, the CPU 191 reads a program and data from a recording medium mounted on, for example, a drive device to the memory 193, and according to this, the DTMF signal erasing device 1 in the first embodiment includes a processing method determination unit 12, a frequency component Various processes are executed as the erasure unit 14, the sound determination unit 15, and the signal replacement unit 16.

  The storage device 194 is, for example, an optical disk, a flexible disk, a magnetic optical disk, an external hard disk, a semiconductor memory, or the like, and records a computer program so that it can be read by a computer. The computer program may be downloaded from an external computer (not shown) connected to the communication network.

  The input device 195 is realized by, for example, a mouse, a keyboard, or a built-in key button, and is used for an input operation. The input device 195 is not limited to a mouse, a keyboard, or a built-in key button, and may be a touch panel, an accelerometer, a gyro sensor, a camera, or the like.

  The output device 196 is realized by a display, for example, and is used for confirming the output.

  Note that the block diagram (FIG. 1) used in the description of the first embodiment shows functional unit blocks, not hardware unit configurations. These functional blocks are realized by the hardware configuration shown in FIG. However, the means for realizing each unit included in the DTMF signal erasing apparatus 1 is not particularly limited. That is, the DTMF signal erasing device 1 may be realized by one physically coupled device, or by two or more physically separated devices connected by wire or wirelessly, and realized by these multiple devices. May be.

  Further, the CPU 191 reads a computer program recorded in the storage device 194, and operates as a processing method determination unit 12, a frequency component elimination unit 14, a sound determination unit 15, and a signal replacement unit 16 according to the program. Also good.

  In addition, a recording medium (or storage medium) in which the above-described program code is recorded may be supplied to the DTMF signal erasing apparatus 1, and the DTMF signal erasing apparatus 1 may read and execute the program code stored in the recording medium. . That is, the present invention also includes a recording medium 198 that temporarily or non-temporarily stores software (information processing program) to be executed by the DTMF signal erasing apparatus 1 according to the first embodiment.

  FIG. 3 is a flowchart showing the operation of the DTMF signal erasing apparatus 1 according to the first embodiment of the present invention.

  The processing method determination unit 12 of the DTMF signal erasing device 1 receives an audio signal (step S1). Then, the processing method determination unit 12 determines whether a signal other than the DTMF signal is included in the audio signal by comparing the signal level of the audio signal with a threshold value (step S2). Details of the determination method in the processing method determination unit 12 will be described later.

  As a result of the determination, when it is determined that the audio signal includes a signal other than the DTMF signal (YES in step S2), the frequency component erasure unit 14 determines the DTMF signal from the audio signal received from the processing method determination unit 12. The frequency component is deleted (step S3). Then, the frequency component erasure unit 14 outputs a first signal that is an audio signal from which the frequency component of the DTMF signal is eliminated.

  The sound determination unit 15 performs the sound determination of the first signal (step S4).

  The processing method determination unit 12 sets a threshold based on the sound determination result of the sound determination unit 15 and the signal level of the received audio signal (step S5).

  On the other hand, when it is determined that the signal other than the DTMF signal is not included in the audio signal as a result of the determination (NO in step S2), the signal replacement unit 16 determines the length of the audio signal received from the processing method determination unit 12. Other signals are generated and replaced with audio signals (step S6). Then, the signal replacement unit 16 outputs a second signal in which the audio signal is replaced with the other signal described above. The other signal generated at this time may be a silence signal or a noise signal.

  Next, a method in which the processing method determination unit 12 determines the DTMF signal erasing method in step S2 will be described. The audio signal received by the DTMF signal erasing apparatus 1 may include only a DTMF signal, or may include a signal other than the DTMF signal (signal such as human voice or BGM (Background Music)). Here, if the signal level of the DTMF signal is substantially the same, the signal level of the audio signal including other audio signals other than the DTMF signal is increased by the signal level of the other audio signals.

  Therefore, in order to determine the presence or absence of an audio signal other than the DTMF signal, the processing method determination unit 12 compares the signal level of the received audio signal with a threshold value. When the signal level is greater than the threshold value, the processing method determination unit 12 determines that the audio signal includes a signal indicating sound other than the DTMF signal. Then, the processing method determination unit 12 passes the received audio signal to the frequency component elimination unit 14 in order to leave only the audio signal other than the DTMF signal (YES in step S2). The frequency component erasure unit 14 erases the frequency component of the DTMF signal (step S3).

  On the other hand, when the signal level of the audio signal is less than the threshold value, the processing method determination unit 12 determines that the audio signal includes only the DTMF signal, and receives the received audio signal to delete the DTMF signal. To the signal replacement unit 16 (NO in step S2). The signal replacement unit 16 replaces the received audio signal with another signal (step S6). Then, the signal replacement unit 16 outputs a second signal in which the audio signal is replaced with the other signal described above.

  The threshold is set based on the result of sound determination performed by the sound determination unit 15 and the signal level of the audio signal received by the processing method determination unit 12. When the sound determination unit 15 determines that the sound signal is sound, it means that the sound signal includes a signal indicating sound other than the DTMF signal. If the sound determination unit 15 determines that the sound signal is not sound, it means that the sound signal does not include a signal indicating sound other than the DTMF signal.

  When the sound determination unit 15 determines that the first signal received from the frequency component elimination unit 14 is not sound, the processing method determination unit 12 compares the signal level of the received audio signal with a threshold value. Then, a new threshold is specified based on those values. For example, the processing method determination unit 12 may specify the average value of the signal level and threshold value of the received audio signal as a new threshold value, or the maximum value of the signal level and threshold value of the received audio signal May be specified as a new threshold value.

  If a large value is set as the threshold value here, a signal including a signal indicating a sound other than the DTMF signal is erroneously determined to be only the DTMF signal. If a small value is set as the threshold value, an audio signal including only the DTMF signal is erroneously determined as including a signal indicating sound other than the DTMF signal. Therefore, it is desirable that the threshold value be close to the maximum value in the signal level of the audio signal determined by the sound determination unit 15 as not sound.

  The DTMF signal erasing apparatus 1 in the first embodiment determines whether or not a signal other than the DTMF signal is included in the audio signal based on the comparison between the signal level of the audio signal and a threshold value. When the DTMF signal erasing apparatus 1 determines that a signal other than the DTMF signal is included, the DTMF signal erasing apparatus 1 erases the frequency component of the DTMF signal from the audio signal. On the other hand, when the DTMF signal erasing apparatus 1 determines that a signal other than the DTMF signal is not included, the DTMF signal erasing apparatus 1 replaces the aforementioned audio signal with another signal. Then, the DTMF signal erasing device 1 performs the sound determination of the audio signal from which the frequency component of the DTMF signal is erased. Then, the DTMF signal erasing apparatus 1 sets the above-described threshold value based on the above-described sound determination result and the signal level of the audio signal.

  Therefore, the DTMF signal erasing apparatus 1 in the first embodiment, when the signal level of the audio signal is compared with the threshold value, when the predetermined condition is satisfied, Processing to replace with signals. Therefore, the DTMF signal elimination device 1 can reduce the number of computations and the amount of computation with a large amount of computation such as a band-pass filter required for the DTMF signal elimination processing, thus increasing the number of conferences that can be processed simultaneously by the teleconference server. It becomes possible to make it.

<Second Embodiment>
FIG. 4 is a block diagram showing a configuration of the DTMF signal erasing apparatus 2 according to the second embodiment of the present invention.

  Referring to FIG. 4, the DTMF signal erasing device 2 includes a signal input unit 21, a processing method determination unit 22, a signal level calculation unit 23, a frequency component erasure unit 24, a sound determination unit 25, and a silence signal generation. Unit 26, signal output unit 27, and signal information storage unit 28.

  The DTMF signal erasing apparatus 2 in the second embodiment determines whether or not a signal other than the DTMF signal is included in the audio signal based on the comparison between the signal level of the audio signal and a threshold value. When the DTMF signal erasing apparatus 2 determines that a signal other than the DTMF signal is not included, the DTMF signal erasing apparatus 2 performs a process of replacing the above-described audio signal with another signal.

  In other words, the DTMF signal erasing apparatus 2 in the second embodiment, when the signal level of the audio signal is compared with the threshold value, satisfies the predetermined condition, Processing to replace with signals. Therefore, the DTMF signal erasure device 2 can reduce the number and the amount of signal processing with a large amount of calculation such as a bandpass filter necessary for DTMF signal erasure processing, so the number of conferences that can be processed simultaneously by the teleconference server is increased. It becomes possible to make it.

  Hereinafter, each component provided in the DTMF signal erasing apparatus 2 according to the second embodiment will be described.

=== Signal Input Unit 21 ===
The signal input unit 21 receives information indicating the audio signal and the type of the DTMF signal included in the audio signal. The signal input unit 21 adds an audio signal identifier that uniquely identifies the received audio signal to information indicating the type of the audio signal and the DTMF signal, and transmits them to the processing method determination unit 22 described later.

  The information indicating the type of DTMF signal may be information indicating the high group frequency and the low group frequency shown in FIG. 19, or information expressed by a combination of the high group frequency and the low group frequency. May be.

=== Processing Method Determination Unit 22 ===
The processing method determination unit 22 receives information indicating the type of the audio signal identifier, the audio signal, and the DTMF signal from the signal input unit 21. Then, the processing method determination unit 22 passes the audio signal to a signal level calculation unit 23 described later.

  The processing method determination unit 22 receives the signal level calculated from the signal level calculation unit 23, associates the above-described audio signal identifier, the audio signal, and information indicating the type of the DTMF signal with a signal information storage unit described later Save to.

  In addition, the processing method determination unit 22 obtains a threshold value from the signal information storage unit 28, and compares the signal level of the received audio information with the threshold value to determine whether the audio signal includes a signal other than the DTMF signal. Determine whether or not. The determination as to whether or not the audio signal includes a signal other than the DTMF signal by the processing method determination unit 22 may be the same as the determination method by the processing method determination unit 12 in the first embodiment.

=== Signal Level Calculation Unit 23 ===
The signal level calculation unit 23 receives the audio signal from the processing method determination unit 22 and calculates the signal level of the audio signal.

=== Frequency Component Erasing Unit 24 ===
The frequency component erasure unit 24 receives information indicating the audio signal identifier, the audio signal, and the type of the DTMF signal from the processing method determination unit 22. Then, the frequency component erasure unit 24 erases the frequency component of the DTMF signal from the audio signal. Then, the frequency component erasure unit 24 passes the audio signal identifier and the first signal that is an audio signal from which the frequency component of the DTMF signal has been erased, to the sound determination unit 25 described later.

=== Sound determination unit 25 ===
The sound determination unit 25 receives the sound signal identifier and the first signal. Then, the sound determination unit 25 determines whether or not the received first signal is sound, and stores the determination result in the signal information storage unit 28.

=== Silence Signal Generation Unit 26 ===
The silence signal generation unit receives the audio signal from the processing method determination unit 22, and generates a silence signal to replace the audio signal. The silence signal generator 26 outputs a second signal in which the audio signal is replaced with a silence signal.

=== Signal Output Unit 27 ===
The signal output unit 27 receives a signal from the sound determination unit 25 or the silence signal generation unit 26 and outputs the signal.

=== Signal Information Storage Unit 28 ===
The signal information storage unit 28 includes a sound signal identifier, information indicating the type of the DTMF signal, the signal level of the sound signal, and the first signal from which the frequency component of the DTMF signal is deleted by the frequency component deleting unit 24 Is stored in association with the sound determination result of the sound determination unit 25 indicating whether or not.

  FIG. 5 is a diagram illustrating an example of information stored in the signal information storage unit 28. As illustrated in FIG. The information stored in association with the signal information storage unit 28 is as follows. First, the audio signal identifier 281 generated by the signal input unit 21 is stored. Second, a DTMF signal type 282 that is information indicating the type of DTMF signal included in the audio signal is stored. Third, the audio signal level 283 of each audio signal calculated by the signal level calculation unit 23 is stored. Fourth, the sound determination result 284 performed by the sound determination unit 25 is stored.

  The sound determination result 284 has a value only for the signal from which the frequency component erasure unit 24 has erased the frequency component. On the other hand, the sound determination result 284 does not have a value when the silence signal generator 26 replaces the sound signal with a silence signal.

  FIG. 6 is a flowchart showing the operation of the DTMF signal erasing apparatus 2 in the second embodiment of the present invention.

  The signal input unit 21 of the DTMF signal erasing device 2 receives the audio signal and information indicating the type of the DTMF signal included in the audio signal (step S21). Then, the signal input unit 21 adds an audio signal identifier to information indicating the types of the audio signal and the DTMF signal, and passes them to the processing method determination unit 22.

  The processing method determination unit 22 passes the audio signal to the signal level calculation unit 23. The signal level calculation unit 23 calculates the signal level of the received audio signal (step S22), and returns the calculation result to the processing method determination unit 22.

  The processing method determination unit 22 is an audio signal identifier. Information indicating the type of the DTMF signal included in the audio signal is associated with the signal level calculated by the signal level calculation unit 23 and stored in the signal information storage unit 28 (step S23). Then, the processing method determination unit 22 retrieves information stored in the past from the signal information storage unit 28, and determines a DTMF signal erasing method (step S24). Details of the determination method in step S24 will be described later.

  As a result of the determination in step S24, when it is determined that the frequency component of the DTMF signal is to be deleted (YES in step S25), the frequency component deleting unit 24 is based on the information indicating the type of the DTMF signal received from the processing method determining unit 22 The frequency to be erased is obtained and the frequency component obtained from the received audio signal is erased (step S27).

  The sound determination unit 25 performs sound determination of the first signal from which the frequency component erasure unit 24 has deleted the frequency component of the DTMF signal, and associates the sound determination result with the sound signal identifier that identifies the corresponding sound signal. And stored in the signal information storage unit 28 (step S28).

  On the other hand, if it is determined in step S24 that the frequency component of the DTMF signal is not to be erased (NO in step S25), the silence signal generator 26 generates silence of the length of the audio signal received from the processing method determiner 22. A signal is generated (step S26). At this time, the signal generated by the silence signal generator 26 may be a noise signal instead of the silence signal. The silence signal generator 26 outputs a second signal in which the audio signal is replaced with a silence signal.

  The signal output unit 27 outputs the first signal from which the frequency component elimination unit 24 erases the frequency component of the DTMF signal or the second signal generated by the silence signal generation unit 26 (step S29).

  Next, the determination method of the DTMF signal erasing method in step S24 will be described. The audio signal received by the DTMF signal erasing device 2 may include only the DTMF signal or may include a signal other than the DTMF signal (signal such as human voice or BGM (Background Music)). Here, if the signal level of the DTMF signal is substantially the same, the signal level of the audio signal including other audio signals other than the DTMF signal is increased by the signal level of the other audio signals.

  Therefore, in order to determine the presence or absence of an audio signal other than the DTMF signal, the processing method determination unit 22 compares the signal level of the received audio signal with a threshold value. Then, when the signal level is greater than the threshold value, the processing method determination unit 22 determines that the audio signal includes a signal indicating sound other than the DTMF signal, and leaves only the audio signal other than the DTMF signal. Then, the frequency component erasure unit 24 is instructed to erase the frequency component of the DTMF signal (step S27).

  On the other hand, if the signal level of the audio signal is equal to or lower than the threshold value, it is determined that the audio signal contains only the DTMF signal, and the silence signal generator 26 generates a silence signal in order to delete the DTMF signal. An instruction is given (step S26).

  The threshold value is determined using information stored in the signal information storage unit 28. The sound determination result 284 stored in the signal information storage unit 28 is a field in which information indicating whether or not the first signal from which the frequency component of the DTMF signal has been deleted in step S27 is sound is stored. It is. That is, when the value of the sound determination result 284 is sound, it means that the sound signal received by the signal input unit 21 includes a signal indicating sound other than the DTMF signal. On the other hand, when the value of the sound determination result 284 is silent, it means that the audio signal does not include a signal indicating sound other than the DTMF signal. From the sound determination result 284 and the information of the audio signal level 283 field, the relationship between the level of the audio signal received by the signal input unit 21 and whether or not a signal indicating sound other than the DTMF signal is included is clarified. Can be.

  For example, the signal of the audio signal identifier “1” shown in FIG. 6 has a signal level of “x1” and includes a signal indicating sound other than the DTMF signal, and the signal of the audio signal identifier “2” has a signal level of “ “x2” means that signals other than DTMF signals are not included.

  In general, data of a DTMF signal transmitted by a communication terminal apparatus is stored in advance in a file, a memory, or the like included in the communication terminal apparatus. Moreover, it can be considered that the signal level of the same kind of DTMF signal transmitted from the same terminal apparatus is substantially constant. For this reason, the sound signal level 283 when the sound determination result 284 is sound is higher than the sound signal level 283 when the sound determination result 284 is silent.

FIG. 7 is a graph showing the relationship between the signal level and the threshold value. Points N _i (i = 1, 2,...) In the figure represent the signal level of the audio signal whose sound determination result by the sound determination unit 25 is “silence”, and N ₁ ≧ N ₂ ≧…. Further, the point A _i (i = 1, 2,...) In the figure represents the signal level of the audio signal whose sound determination result by the sound determination unit 25 is “sound”, and A ₁ ≦ A ₂ ≦….

If a large value is set as the threshold value here, a signal including a signal indicating a sound other than the DTMF signal is erroneously determined to be only the DTMF signal. If a small value is set as the threshold value, an audio signal including only the DTMF signal is erroneously determined as including a signal indicating sound other than the DTMF signal. Therefore, it is desirable that the threshold value be near the value of N ₁ (the point at which the level is maximum in silence).

  The DTMF signal erasing apparatus 2 in the second embodiment determines whether or not a signal other than the DTMF signal is included in the audio signal based on the comparison between the signal level of the audio signal and a threshold value. When the DTMF signal erasing device 2 determines that a signal other than the DTMF signal is included, the DTMF signal erasing device 2 erases the frequency component of the DTMF signal from the audio signal. On the other hand, when the DTMF signal erasing apparatus 2 determines that a signal other than the DTMF signal is not included, the DTMF signal erasing apparatus 2 replaces the above-described audio signal with another signal. Then, the DTMF signal erasing device 2 performs the sound determination of the audio signal from which the frequency component of the DTMF signal is erased. Then, the DTMF signal erasing device 2 sets the above-described threshold based on the above-described sound determination result and the signal level of the audio signal.

  Therefore, the DTMF signal erasing apparatus 2 according to the second embodiment, when the signal level of the audio signal is compared with the threshold value, when the predetermined condition is satisfied, Processing to replace with signals. Therefore, the DTMF signal erasure device 2 can reduce the number and the amount of signal processing with a large amount of calculation such as a bandpass filter necessary for DTMF signal erasure processing, so the number of conferences that can be processed simultaneously by the teleconference server is increased. It becomes possible to make it.

<Third embodiment>
Next, a third embodiment of the present invention will be described.

  The DTMF signal erasing device 2 in the third embodiment is different from the DTMF signal erasing device 2 in the second embodiment in the following two points. The first point is that the signal input unit 21 receives information indicating the frequency strength of the DTMF signal in addition to the information indicating the audio signal and the type of the DTMF signal included in the audio signal, and transmits the received information to the processing method determination unit 22 Is a point. The second point is a threshold value setting method for the processing method determination unit 22 to determine the DTMF signal erasing method in step S24. Here, the frequency strength of the DTMF signal is the strength of the frequency component of each of the low group and the high group of the received DTMF signal. For example, in the case of the DTMF signal “1”, it is the strength of the frequency components of 697 Hz and 1209 Hz. .

  Next, a threshold value setting method in the third embodiment will be described. The processing method determination unit 22 generates an audio signal of a DTMF signal composed of the frequency intensity of the DTMF signal received from the signal input unit 21. The signal level calculation unit 23 calculates the signal level of the audio signal generated by the processing method determination unit 22. The calculated signal level represents teacher information of signal strength when the received audio signal is only a DTMF signal.

That is, when the audio signal received by the signal input unit 21 does not include a signal indicating sound other than the DTMF signal, the signal level of the audio signal generated by the processing method determination unit 22 and the audio received by the signal input unit 21 The signal levels of the signals match. Therefore, the signal level of the audio signal generated by the processing method determination unit 22 is set to one of N _i (N _x ) in FIG. At this time, considering that the audio signal received by the signal input unit 21 may include noise, the processing method determination unit 22 sets N _x to be larger than the signal level of the generated audio signal. Also good. The subsequent processing is similar to the second embodiment, process determining unit 22 determines a threshold value based on the point N _i and A _i, determine the method of erasing a DTMF signal.

  Next, the effect of the third embodiment will be described. Since the DTMF signal erasing apparatus 2 in the second embodiment does not set a threshold until the sound determination unit 25 determines that there is no sound, the frequency component erasure unit 24 performs frequency component erasure with a large amount of calculation. It was. In the DTMF signal erasing apparatus 2 in the third embodiment, the processing method determination unit 22 can set a threshold value for the first data by setting the threshold value using the frequency intensity of the DTMF signal. Therefore, the DTMF signal erasing apparatus 2 in the third embodiment can reduce the number of frequency component erasures and can reduce the amount of calculation.

  In addition, the DTMF signal erasing device 2 in the third embodiment does not generate a sound signal of the DTMF signal each time, but calculates the signal levels of various strengths in advance, thereby further reducing the amount of calculation. Is possible.

<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described.

  FIG. 8 is a block diagram showing an example of a configuration of the telephone conference server device 40 in the fourth embodiment. Referring to FIG. 8, the DTMF signal erasing apparatus 2 of the fourth embodiment is included in the telephone conference server apparatus 40.

  The teleconference server device 40 in the fourth embodiment includes an audio signal receiving unit 41, a DTMF signal detecting unit 42, a DTMF signal erasing device 2, an audio signal synthesizing unit 43, and an audio signal transmitting unit 44. . Note that there are as many audio signal receivers 41, DTMF signal detectors 42, DTMF signal erasing devices 2 and audio signal transmitters 44 as there are terminals participating in the conference.

=== Audio Signal Receiver 41 ===
The audio signal receiving unit 41 receives an audio signal from each terminal participating in the conference. The audio signal receiving unit 41 passes the received audio signal to the DTMF signal detecting unit 42.

=== DTMF signal detector 42 ===
The DTMF signal detector 42 detects the DTMF signal included in the audio signal received by the audio signal receiver 41. When the DTMF signal detection unit 42 determines that the audio signal includes the DTMF signal, the DTMF signal detection unit 42 transmits at least the audio signal and information indicating the type of the DTMF signal included in the audio signal to the DTMF signal erasing device 2. Send. The DTMF signal detection unit 42 may transmit information indicating the frequency strength of the DTMF signal to the DTMF signal erasing device 2.

  On the other hand, if the DTMF signal detection unit 42 determines that the DTMF signal is not included in the audio signal received by the audio signal reception unit 41, the DTMF signal detection unit 42 passes the audio signal to the audio signal synthesis unit 43.

=== DTMF signal erasing device 2 ===
The DTMF signal erasing device 2 receives the audio signal from the DTMF signal detection unit 42 and erases the DTMF signal. Then, the DTMF signal erasing device 2 passes the audio signal from which the DTMF signal has been deleted to the audio signal synthesis unit 43.

  The configuration and operation of the DTMF signal erasing device 2 are the same as the configuration and operation of the DTMF signal erasing device 2 in the second or third embodiment.

  FIG. 9 is a block diagram showing another example of the configuration of the telephone conference server device 40 according to the fourth embodiment. FIG. 10 is a diagram showing another example of information stored in the signal information storage unit.

  Referring to FIG. 9, one DTMF signal erasing device 2 is included in the telephone conference server device 40. Then, the DTMF signal erasing device 2 may erase the DTMF signal in the audio signals received from a plurality of terminals as shown in FIG. At this time, the signal information storage unit 28 of the DTMF signal erasing apparatus 2 may store information for each terminal as shown in FIG. In this case, the signal information storage unit 28 may store the audio signal identifier, the DTMF signal type, the audio signal level, and the sound determination result in association with the terminal identifier for identifying the terminal.

  Also, at this time, information passed from the signal input unit 21 to the processing method determination unit 22, information passed from the processing method determination unit 22 to the frequency component elimination unit 24, information passed from the processing method determination unit 22 to the silence signal generation unit 26 Information passed from the frequency component elimination unit 24 to the sound determination unit 25, information passed from the sound determination unit 25 to the signal output unit 27, and information passed from the silence signal generation unit 26 to the signal output unit 27, A terminal identifier that can identify each terminal is included.

  The teleconference server device 40 according to the fourth embodiment can reduce the number and amount of computation of a large amount of signal processing such as a band-pass filter that the DTMF signal erasing device 2 was necessary for DTMF signal erasing processing. It is possible to increase the number of conferences that can be processed simultaneously.

<Fifth embodiment>
Next, a fifth embodiment of the present invention will be described. FIG. 11 is a block diagram showing an example of the configuration of the DTMF signal conversion apparatus 50 in the fifth embodiment. Referring to FIG. 11, the DTMF signal erasing apparatus 2 in the fifth embodiment is included in the DTMF signal converting apparatus 50. The DTMF signal conversion device 50 is a device that converts a DTMF signal received as an audio signal into a control signal.

  The DTMF signal conversion device 50 according to the fifth embodiment includes an audio signal receiving unit 51, a DTMF signal detecting unit 52, a DTMF signal erasing device 2, an audio signal transmitting unit 53, and a control signal transmitting unit 54. . The configuration and operation of the DTMF signal erasing device 2 are the same as the configuration and operation of the DTMF signal erasing device 2 in the second or third embodiment.

=== Audio Signal Receiver 51 ===
The audio signal receiving unit 51 receives an audio signal from a terminal or the like. Then, the audio signal receiving unit 51 passes the received audio signal to the DTMF signal detecting unit 52.

=== DTMF Signal Detection Unit 52 ===
The DTMF signal detector 52 detects a DTMF signal included in the audio signal received by the audio signal receiver 51. When the DTMF signal detecting unit 52 determines that the audio signal includes the DTMF signal, the DTMF signal erasing apparatus 2 transmits at least the audio signal and information indicating the type of the DTMF signal included in the audio signal to the DTMF signal erasing apparatus 2. Send. The DTMF signal detection unit 52 may transmit information indicating the frequency strength of the DTMF signal to the DTMF signal erasing device 2. In addition, the DTMF signal detection unit 52 instructs the control signal transmission unit 54 to transmit the detected DTMF signal as a control signal.

  The DTMF signal erasing device 2 receives the audio signal from the DTMF signal detection unit 52, deletes the DTMF signal included in the audio signal, and passes it to the audio signal transmission unit 53.

  On the other hand, when the DTMF signal detection unit 52 determines that the DTMF signal is not included in the audio signal received by the audio signal reception unit 51, the DTMF signal detection unit 52 passes the audio signal to the audio signal transmission unit 53.

=== Audio Signal Transmitter 53 ===
The audio signal transmitting unit 53 transmits the first signal from the DTMF signal erasing apparatus 2 from which the DTMF signal has been deleted or the audio signal transferred from the DTMF signal detecting unit 52 to a terminal or the like.

=== Control Signal Transmitter 54 ===
The control signal transmission unit 54 transmits the DTMF signal as a control signal to the terminal or the like.

<Specific example of the second embodiment>
Next, the operation of the second exemplary embodiment will be described using a specific example.

  The DTMF signal erasing device 2 in this specific example is a server device, and the signal input unit 21 and the signal output unit 27 are realized by a combination of a network interface of the server device and a program executed by the CPU. The processing method determination unit 22, the signal level calculation unit 23, the frequency component elimination unit 24, the sound determination unit 25, and the silence signal generation unit 26 are realized by a program executed by the CPU of the server device. The signal information storage unit 28 is realized by a part of the main storage device of the server device.

  The signal input unit 21 receives the audio signal sampled at 8 kHz and the type of the DTMF signal included in the audio signal. Here, it is assumed that the signal input unit 21 receives an audio signal in units of 102 samples (12.75 seconds). The signal input unit 21 adds an audio signal identifier to the received information and transmits the information to the processing method determination unit 22. In this specific example, the audio signal identifier is a serial number from 1.

  The processing method determination unit 22 transmits the received audio signal to the signal level calculation unit 23. The processing method determination unit 22 receives the signal level calculated by the signal level calculation unit 23 and stores the audio signal identifier, the DTMF signal type, and the signal level in the signal information storage unit 28.

  Here, the DTMF signal type of the DTMF signal included in the audio signal received by the processing method determination unit 22 is set to “1” (FIG. 12). The signal level calculated by the signal level calculation unit 23 is the sum of squares of the intensities of the respective audio samples. Other signal intensity calculation methods may be the absolute value sum of the intensity of each audio sample, the maximum absolute value of the intensity, or the like.

  FIG. 12 is a diagram illustrating an example of information stored in the signal information storage unit 28 by the processing method determination unit 22. Referring to FIG. 12, the signal information storage unit 28 stores “1” as the audio signal identifier 281, “1” as the DTMF signal type 282, and “100.0” as the audio signal level 283.

  Next, the processing method determination unit 22 determines the DTMF signal erasing method. At this point in time, there is no audio signal determined by the sound determination unit 25 as silence, so the processing method determination unit 22 cannot determine the threshold value. Therefore, the processing method determination unit 22 selects frequency component erasing as the DTMF signal erasing method, and transmits the audio signal identifier, the audio signal, and the DTMF signal type, which is the type of the DTMF signal, to the frequency component erasing unit 24.

  The frequency component elimination unit 24 refers to the table of FIG. 19 and detects that the received DTMF signal type “1” is composed of 697 Hz and 1209 Hz. The frequency component erasure unit 24 then erases these frequency components from the audio signal using a bandpass filter or the like, and transmits the audio signal identifier and the audio signal after erasure to the sound determination unit 25.

  The sound determination unit 25 determines whether or not the received sound signal is sound, and stores the result in the sound determination result 284 of the signal information storage unit 28 (FIG. 13). As the sound determination method, a method of comparing the signal level calculated by the same method as the signal level calculation unit 23 with a threshold value, to determine the sound / silence specified in ITU-T G.729 Annex B A method that uses the VAD (Voice Activity Detection) algorithm is considered.

  FIG. 13 is a diagram illustrating an example of information stored in the signal information storage unit 28 by the sound determination unit 25. As illustrated in FIG. Referring to FIG. 13, the signal information storage unit 28 is “1” as the audio signal identifier 281, “1” as the DTMF signal type 282, “100.0” as the audio signal level 283, and “sound” as the sound determination result 284. Are stored in association with each other.

  The sound signal after the sound determination processing by the sound determination unit 25 is transmitted to the signal output unit 27 and then transmitted from the network interface to the outside.

  The same processing is performed for subsequent audio signals until a threshold value can be set, that is, until an audio signal determined to be silent by the sound determination unit 25 appears. If the sound determination result in the sound determination unit 25 becomes silent for the first time with the sound signal with the sound signal identifier “6” (FIG. 14), the signal level of this sound signal is the following sound signal. 70.5 is set as a threshold value in the processing method determination unit 22, and if it is equal to or greater than the threshold value, the frequency component is deleted, and if it is less than the threshold value, it is replaced with a silence signal.

  FIG. 14 is an example of information stored in the signal information storage unit 28. Referring to FIG. 14, the signal information storage unit 28 stores at least three pieces of information. The first is information associated with “1” as the audio signal identifier 281, “1” as the DTMF signal type 282, “100.0” as the audio signal level 283, and “sound” as the sound determination result 284. The second information is associated with “5” as the audio signal identifier 281, “1” as the DTMF signal type 282, “102.1” as the audio signal level 283, and “sound” as the sound determination result 284. The third is information in which “6” is associated with the audio signal identifier 281, “1” as the DTMF signal type 282, “70.5” as the audio signal level 283, and “silence” as the sound determination result 284.

  When the signal level of the audio signal of the next audio signal identifier “7” is 66.0 (FIG. 15), since this signal level is less than the threshold value, the processing method determination unit 22 selects the replacement with the silence signal, The silence signal generator 26 generates a silence signal and outputs it from the signal output unit 27. At this time, since the frequency component erasure unit 24 and the sound determination unit 25 do not perform frequency component deletion and sound determination, respectively, the sound determination result 284 in the signal information storage unit 28 is blank.

  FIG. 15 is an example of information stored in the signal information storage unit 28. Referring to FIG. 15, the signal information storage unit 28 further stores one piece of information with respect to the case of FIG. The information is information associated with “7” as the audio signal identifier 281, “1” as the DTMF signal type 282, and “66.0” as the audio signal level 283. As described above, the sound determination result 284 is not associated with this information.

  Also, like the audio signal of the audio signal identifier “8” in FIG. 16, the audio signal has a higher signal level than the threshold 70.5, but if the sound determination unit 25 determines that there is no sound, The processing method determination unit 22 updates the threshold value to 80.0.

  FIG. 16 is a diagram illustrating an example of information stored in the signal information storage unit 28 when the processing method determination unit 22 updates the threshold value to 80.0. Referring to FIG. 16, the signal information storage unit 28 further stores one piece of information with respect to the case of FIG. The information is associated with “8” as the audio signal identifier 281, “1” as the DTMF signal type 282, “80.0” as the audio signal level 283, and “silence” as the sound determination result 284. The processing method determination unit 22 updates the threshold value to 80.0 because it is determined that an audio signal having a signal level “80.0” greater than the current threshold value is silent.

  Next, consider a case where the DTMF signal erasing apparatus 2 receives the signal of the audio signal identifier “9” in FIG. The audio signal identifier “9” is “2”, which is different from the DTMF signal type. Generally, even if the DTMF signal type is different, the strength of the DTMF signal transmitted from the terminal is almost the same, so the processing method determination unit 22 uses the threshold value in the case of the DTMF signal type “1” as it is. .

  FIG. 17 is a diagram illustrating an example of information stored in the signal information storage unit 28. As illustrated in FIG. Referring to FIG. 17, the signal information storage unit 28 further stores one piece of information with respect to the case of FIG. The information is information in which “9” is associated with the audio signal identifier 281, “2” is associated with the DTMF signal type 282, and “75.0” is associated with the audio signal level 283. Since the signal level of the sound signal with the sound signal identifier “9” is less than the threshold value of 80.0, the frequency component erasure unit 24 and the sound determination unit 25 do not perform frequency component deletion and sound determination, respectively. Therefore, the sound determination result 284 in the signal information storage unit 28 is blank.

  Here, the processing method determination unit 22 may use a different threshold value for each DTMF signal type. Depending on the terminal, the signal strength of the audio signal to be transmitted may differ for each DTMF signal type. By using a different threshold value for each signal type by the processing method determination unit 22, erroneous detection at the terminal can be prevented even in the above-described case.

  In addition, the processing method determination unit 22 uses different threshold values for each DTMF signal type immediately after the start of the session, and after processing audio signals of several types of DTMF signal types, the respective threshold values are close to each other. It may be determined whether or not to make them common. When the processing method determination unit 22 uses a different threshold value for each signal type, it is necessary to delete a large frequency component until the threshold setting is completed, but the threshold value is shared in the middle. As a result, the number of frequency component erasures can be reduced and the load can be reduced.

<Specific example of the third embodiment>
Next, a specific example of the third embodiment will be described.

  First, it is assumed that the signal input unit 21 receives an audio signal whose DTMF signal type is “1”, the frequency intensity at the frequency 697 Hz is −15 dB, and the frequency intensity at the frequency 1209 kHz is −13 dB. The signal input unit 21 adds the audio signal identifier “1” to the received information and transmits it to the processing method determination unit 22.

  The processing method determination unit 22 transmits the received audio signal to the signal level calculation unit 23. The processing method determination unit 22 receives the signal level calculated by the signal level calculation unit 23, and stores the audio signal identifier, the DTMF signal type, and the signal level in the signal information storage unit 28 (FIG. 18). FIG. 18 is a diagram illustrating an example of information stored in the signal information storage unit 28 by the processing method determination unit 22. Referring to FIG. 18, the signal information storage unit 28 stores “1” as the audio signal identifier 281, “1” as the DTMF signal type 282, and “100.0” as the audio signal level 283.

  Next, the processing method determination unit 22 generates an audio signal that combines a sine wave with a frequency intensity of −15 dB at a frequency of 697 Hz and a sine wave with a frequency intensity of −13 dB at a frequency of 1209 Hz, and transmits the audio signal to the signal level calculation unit 23 To do. The signal level calculation unit 23 calculates the signal level of the received audio signal and sets this as Ni. The subsequent processing is the same as the specific example of the second embodiment.

<Specific example of the fourth embodiment>
Next, a specific example of the fourth embodiment will be described.

  The telephone conference server device 40 in this specific example is a server device, and the audio signal receiving unit 41 and the audio signal transmitting unit 44 are realized by a combination of a network interface of the server device and a program executed by the CPU. The DTMF signal detection unit 42 and the audio signal synthesis unit 43 are realized as programs executed by the CPU of the server device.

  The DTMF signal erasing device 2 of this specific example is a software library, and the signal input unit 21 and the signal output unit 27 are realized by a combination of a part of the main storage device of the server device and a program executed by the CPU. This is different from the specific example of the second embodiment and the specific example of the third embodiment.

  Other configurations and operations are the same as the specific example of the second embodiment and the specific example of the third embodiment.

<Specific example of the fifth embodiment>
Next, a specific example of the fifth embodiment will be described.

  The DTMF signal conversion device 50 in this specific example is a server device, and the audio signal receiving unit 51, the audio signal transmitting unit 53, and the control signal transmitting unit 54 are realized by a combination of a network interface of the server device and a program executed by the CPU. Is done. The DTMF signal detection unit 52 is realized by a program executed by the CPU of the server device.

  As in the specific example of the fourth embodiment, the DTMF signal erasing device 2 of this specific example is also a combination of a program that the signal input unit 21 and the signal output unit 27 execute with a part of the main storage device of the server device and the CPU. This is different from the specific example of the second embodiment and the specific example of the third embodiment.

  Other configurations and operations are the same as the specific example of the second embodiment and the specific example of the third embodiment.

  Although the present invention has been described with reference to each embodiment and specific examples, the present invention is not limited to the above-described embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  In addition, each component in each embodiment of the present invention can be realized by a computer and a program as well as its function in hardware. The program is provided by being recorded on a computer-readable recording medium such as a magnetic disk or a semiconductor memory, and is read by the computer when the computer is started up. The read program causes the computer to function as a component in each of the embodiments described above by controlling the operation of the computer.

  A part or all of each of the above embodiments can be described as in the following supplementary notes, but is not limited thereto.

(Appendix 1)
A processing method determination unit that determines whether a signal other than a DTMF (Dual-Tone Multi-Frequency) signal is included in the audio signal based on a comparison between the signal level of the audio signal and a threshold;
When a signal other than a DTMF signal is included, a frequency component erasure unit that outputs a first signal in which the frequency component of the DTMF signal is eliminated from the audio signal;
When a signal other than a DTMF signal is not included, a signal replacement unit that outputs a second signal in which the audio signal is replaced with another signal; and
The frequency component erasure unit comprises a sound determination unit that performs sound determination of the first signal,
The DTMF signal erasing apparatus, wherein the processing method determination unit sets the threshold based on a sound determination result of the sound determination unit and the signal level of the audio signal.

(Appendix 2)
A DTMF signal erasing device according to appendix 1,
The DTMF signal erasing apparatus, wherein the processing method determination unit receives the type of the DTMF signal and sets the threshold value for each type of the DTMF signal.

(Appendix 3)
A DTMF signal erasing device according to appendix 2,
The processing method determination unit is a DTMF signal erasing device that makes common when any of the threshold values for each type of the DTMF signal is close to each other.

(Appendix 4)
A DTMF signal erasing device according to any one of appendices 1 to 3,
The DTMF signal erasing apparatus, wherein the processing method determination unit sets the threshold based on the intensity of a frequency component of a DTMF signal included in the audio signal.

(Appendix 5)
A DTMF signal erasing device according to appendix 4,
The processing method determination unit generates an audio signal composed of frequency components corresponding to the type of the DTMF signal based on the type of the DTMF signal and the intensity of the DTMF signal, and sets the signal level of the generated audio signal. A DTMF signal erasing device that sets the threshold based on the DTMF signal.

(Appendix 6)
A DTMF signal erasing device according to any one of appendices 1 to 5,
The DTMF signal erasing device, wherein the signal replacement unit replaces the audio signal with a noise signal or a silence signal.

(Appendix 7)
The DTMF signal erasing device according to any one of appendices 1 to 6,
An audio signal receiver for receiving audio signals from the terminal;
DTMF signal detection unit that detects a DTMF signal included in the received audio signal, performs processing corresponding to the DTMF signal, and outputs the audio signal and the DTMF signal to the DTMF signal erasing device;
An audio signal synthesizer for synthesizing the audio signal from which the DTMF signal erasing device has erased the DTMF signal;
An audio signal transmitting unit for transmitting the synthesized audio signal to the terminal;
A telephone conference server device comprising:

(Appendix 8)
DTMF signal erasing device according to any one of appendices 1 to 6,
An audio signal receiving unit for receiving an audio signal;
A DTMF signal detection unit that detects a DTMF signal included in the received audio signal and outputs the audio signal and the DTMF signal to a DTMF signal erasing device;
An audio signal transmitting unit that transmits an audio signal from which the DTMF signal is erased by the DTMF signal erasing device;
A control signal transmitter for transmitting the DTMF signal;
DTMF signal conversion device.

(Appendix 9)
The DTMF signal erasing device according to any one of appendices 1 to 6,
The processing method determination unit sets a threshold value for determining whether or not a sound other than a DTMF signal is included. If the signal level is equal to or higher than the threshold value, a sound other than a DTMF signal is included. A DTMF signal erasing device that determines that the sound other than the DTMF signal is not included when it is less than the threshold value.

(Appendix 10)
The DTMF signal erasing device according to any one of appendices 1 to 6 and 9,
A signal information storage unit for storing a result of the sound determination of the sound determination unit;
The DTMF signal erasing device, wherein the processing method determination unit sets the threshold based on a result of the sound determination stored in the signal information storage unit.

(Appendix 11)
The DTMF signal erasing device according to any one of appendices 1 to 6 and 9 to 10,
The processing method determination unit sets a new threshold value for the signal level of the audio signal and the threshold value when the sound determination unit determines that the sound determination unit is not sound. .

(Appendix 12)
The DTMF signal erasing device according to any one of appendices 1 to 6 and 9 to 11,
The processing method determination unit sets a larger value as a new threshold value between the signal level and the threshold value of the audio signal when the sound determination unit determines that the sound determination unit is not sound; DTMF signal eraser.

(Appendix 13)
Determine whether the audio signal contains a signal other than the DTMF (Dual-Tone Multi-Frequency) signal based on the comparison between the signal level of the audio signal and the threshold,
When a signal other than the DTMF signal is included, the first signal in which the frequency component of the DTMF signal is deleted from the audio signal is output.
When the signal other than the DTMF signal is not included, the second signal obtained by replacing the audio signal with another signal is output,
Make a sound determination of the first signal,
A DTMF signal erasing method, wherein the threshold value is set based on a result of the sound determination and the signal level of an audio signal.

(Appendix 14)
A DTMF signal erasing method according to appendix 13,
A DTMF signal erasing method that sets the threshold value for each type of the DTMF signal.

(Appendix 15)
A DTMF signal erasing method according to appendix 14,
A DTMF signal erasing method in which, when any of the threshold values for each type of DTMF signal is close to each other, they are shared.

(Appendix 16)
A DTMF signal erasing method according to any one of appendices 13 to 15,
A DTMF signal erasing method, wherein the threshold value is set based on an intensity of a frequency component of a DTMF signal included in the audio signal.

(Appendix 17)
The DTMF signal erasing method according to appendix 16,
Based on the type of the DTMF signal and the strength of the DTMF signal, an audio signal composed of a frequency component corresponding to the type of the DTMF signal is generated, and the threshold is set based on the signal level of the generated audio signal. The DTMF signal deletion method to be set.

(Appendix 18)
A DTMF signal erasing method according to any one of appendices 13 to 17,
A DTMF signal erasing method for replacing the audio signal with a noise signal or a silence signal when a signal other than a DTMF signal is not included.

(Appendix 19)
Receive audio signals from your device,
The DTMF signal included in the received audio signal is detected, processing corresponding to the DTMF signal is performed, and the DTMF signal erasure according to any one of appendixes 13 to 18 is performed based on the audio signal and the DTMF signal Delete the DTMF signal by the method,
Synthesizes the audio signal from which the DTMF signal has been deleted,
A telephone conference server control method for transmitting a synthesized voice signal to the terminal.

(Appendix 20)
Receive audio signals,
Detecting a DTMF signal included in the received audio signal, and deleting the DTMF signal based on the audio signal and the DTMF signal by the DTMF erasing method according to any one of appendix 13 to appendix 18,
Send the audio signal that erased the DTMF signal,
A DTMF signal conversion method for transmitting the DTMF signal.

(Appendix 21)
The DTMF signal erasing method according to any one of appendices 13 to 18,
A threshold for determining whether or not a sound other than a DTMF signal is included is set, and when the signal level is equal to or higher than the threshold, it is determined that a sound other than a DTMF signal is included. A DTMF signal erasing method that determines that no sound other than the DTMF signal is included when the threshold value is below.

(Appendix 22)
The DTMF signal erasing method according to any one of appendices 13 to 18 and 21,
The result of the sound determination is stored in a signal information storage unit,
A DTMF signal erasing method, wherein the threshold value is set based on a result of the sound determination stored in the signal information storage unit.

(Appendix 23)
The DTMF signal erasing method according to any one of appendices 13 to 18 and 21 to 22,
A DTMF signal erasing method that sets, as a new threshold value, either the signal level of the audio signal or the threshold value when it is determined that there is no sound.

(Appendix 24)
The DTMF signal erasing method according to any one of appendices 13 to 18 and 21 to 23,
A DTMF signal erasing method, wherein a larger one of the signal level and the threshold value of the audio signal when it is determined that there is no sound is set as a new threshold value.

(Appendix 25)
On the computer,
A process for determining whether a signal other than a DTMF (Dual-Tone Multi-Frequency) signal is included in the audio signal based on a comparison between the signal level of the audio signal and a threshold;
When a signal other than the DTMF signal is included, a process of outputting the first signal in which the frequency component of the DTMF signal is deleted from the audio signal;
When a signal other than a DTMF signal is not included, a process of outputting a second signal obtained by replacing the audio signal with another signal;
Processing to determine whether the first signal is sounded;
A DTMF signal erasing program for executing the process of setting the threshold based on the result of the sound determination and the signal level of the audio signal.

(Appendix 26)
A DTMF signal erasing program according to attachment 25,
In the computer,
A DTMF signal erasing program for executing processing for setting the threshold value for each type of the DTMF signal.

(Appendix 27)
A DTMF signal erasing program according to attachment 26,
In the computer,
A DTMF signal erasing method for executing a process of making them common when any of the threshold values for each type of the DTMF signal is close to each other.

(Appendix 28)
A DTMF signal erasing program according to any one of appendices 25 to 27,
In the computer,
A DTMF signal erasing program for executing processing for setting the threshold based on the intensity of a frequency component of a DTMF signal included in the audio signal.

(Appendix 29)
A DTMF signal erasing program according to attachment 28,
In the computer,
Based on the type of the DTMF signal and the strength of the DTMF signal, an audio signal composed of a frequency component corresponding to the type of the DTMF signal is generated, and the threshold is set based on the signal level of the generated audio signal. DTMF signal erasure program for executing the setting process.

(Appendix 30)
A DTMF signal erasing program according to any one of appendices 25 to 29,
In the computer,
A DTMF signal erasing program for executing processing for replacing the audio signal with a noise signal or a silence signal when a signal other than a DTMF signal is not included.

(Appendix 31)
A DTMF signal erasing program according to any one of appendices 25 to 30,
In the computer,
Processing for storing the result of the sound determination in the signal information storage unit;
A DTMF signal erasing program for executing the processing for setting the threshold value based on the sound determination result stored in the signal information storage unit.

(Appendix 32)
The DTMF signal erasing program according to any one of appendices 25 to 31,
In the computer,
A DTMF signal erasing program for executing processing for setting, as a new threshold value, either the signal level or the threshold value of the audio signal when it is determined that there is no sound.

(Appendix 33)
The DTMF signal erasing program according to any one of appendices 25 to 32,
In the computer,
A DTMF signal erasing program for executing a process of setting a larger value as a new threshold value between the signal level and the threshold value of the audio signal when it is determined that there is no sound.

This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2012-214872 for which it applied on September 27, 2012, and takes in those the indications of all here.
[Industrial applicability]
As an example of use of the present invention, a teleconference server device for conducting a conference call with a plurality of terminals, a DTMF signal conversion device that converts in-band and out-of-band DTMF signals, and audio from the terminals There is an answering machine server for recording.

DESCRIPTION OF SYMBOLS 1, 2 DTMF signal elimination apparatus 12, 22 Processing method determination part 13 Signal level calculation part 14 Frequency component elimination part 15 Sound determination part 16 Signal substitution part 21 Signal input part 26 Silent signal generation part 27 Signal output part 28 Signal information storage Unit 40 Telephone conference server device 41, 51 Audio signal receiver 42, 52 DTMF signal detector 43 Audio signal synthesizer 44, 53 Audio signal transmitter 50 DTMF signal converter 54 Control signal transmitter 191 CPU
192 Communication I / F
193 Memory 194 Storage device 195 Input device 196 Output device 197 Bus 198 Recording medium 281 Audio signal identifier 282 DTMF signal type 283 Audio signal level 284 Sound determination result

Claims (10)

A processing method determination unit that determines whether a signal other than a DTMF (Dual-Tone Multi-Frequency) signal is included in the audio signal based on a comparison between the signal level of the audio signal and a threshold;
When a signal other than a DTMF signal is included, a frequency component erasure unit that outputs a first signal in which the frequency component of the DTMF signal is eliminated from the audio signal;
When a signal other than a DTMF signal is not included, a signal replacement unit that outputs a second signal in which the audio signal is replaced with another signal; and
The frequency component erasure unit comprises a sound determination unit that performs sound determination of the first signal,
The DTMF signal erasing apparatus, wherein the processing method determination unit sets the threshold based on a sound determination result of the sound determination unit and the signal level of the audio signal. The DTMF signal erasing device according to claim 1,
The DTMF signal erasing apparatus, wherein the processing method determination unit receives the type of the DTMF signal and sets the threshold value for each type of the DTMF signal. The DTMF signal erasing device according to claim 2,
The processing method determination unit is a DTMF signal erasing device that makes common when any of the threshold values for each type of the DTMF signal is close to each other. The DTMF signal erasing device according to any one of claims 1 to 3,
The DTMF signal erasing apparatus, wherein the processing method determination unit sets the threshold based on the intensity of a frequency component of a DTMF signal included in the audio signal. The DTMF signal erasing device according to claim 4,
The processing method determination unit generates an audio signal composed of frequency components corresponding to the type of the DTMF signal based on the type of the DTMF signal and the intensity of the DTMF signal, and sets the signal level of the generated audio signal. A DTMF signal erasing device that sets the threshold based on the DTMF signal. A DTMF signal erasing device according to any one of claims 1 to 5,
The DTMF signal erasing device, wherein the signal replacement unit replaces the audio signal with a noise signal or a silence signal. A DTMF signal erasing device according to any one of claims 1 to 6,
An audio signal receiver for receiving audio signals from the terminal;
DTMF signal detection unit that detects a DTMF signal included in the received audio signal, performs processing corresponding to the DTMF signal, and outputs the audio signal and the DTMF signal to the DTMF signal erasing device;
An audio signal synthesizer for synthesizing the audio signal from which the DTMF signal erasing device has erased the DTMF signal;
An audio signal transmitting unit for transmitting the synthesized audio signal to the terminal;
A telephone conference server device comprising: A DTMF signal erasing device according to any one of claims 1 to 6,
An audio signal receiving unit for receiving an audio signal;
A DTMF signal detection unit that detects a DTMF signal included in the received audio signal and outputs the audio signal and the DTMF signal to a DTMF signal erasing device;
An audio signal transmitting unit that transmits an audio signal from which the DTMF signal is erased by the DTMF signal erasing device;
A control signal transmitter for transmitting the DTMF signal;
DTMF signal conversion device. Determine whether the audio signal contains a signal other than the DTMF (Dual-Tone Multi-Frequency) signal based on the comparison between the signal level of the audio signal and the threshold,
When a signal other than the DTMF signal is included, the first signal in which the frequency component of the DTMF signal is deleted from the audio signal is output.
When the signal other than the DTMF signal is not included, the second signal obtained by replacing the audio signal with another signal is output,
Make a sound determination of the first signal,
A DTMF signal erasing method, wherein the threshold value is set based on a result of the sound determination and the signal level of an audio signal. On the computer,
A process for determining whether a signal other than a DTMF (Dual-Tone Multi-Frequency) signal is included in the audio signal based on a comparison between the signal level of the audio signal and a threshold;
When a signal other than the DTMF signal is included, a process of outputting the first signal in which the frequency component of the DTMF signal is deleted from the audio signal;
When a signal other than a DTMF signal is not included, a process of outputting a second signal obtained by replacing the audio signal with another signal;
Processing to determine whether the first signal is sounded;
A DTMF signal erasing program for executing the process of setting the threshold based on the result of the sound determination and the signal level of the audio signal.

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