JP2005191966A - Sound echo preventing apparatus, system, method, and program, and centralized management device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a sound echo etc. by simple constitution and at low costs while reducing the processing burden of a CPU without using special hardware. <P>SOLUTION: This sound echo prevention device 1 can communicate with another sound echo prevention device through a network, and is provided with an echo prevention function by an application program 3 for packet sound speech for on/off-controlling at least either voice input on the side of its own device or voice input on the side of another sound echo prevention device through the network in the case of speech. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an acoustic echo prevention device, a central management device, an acoustic echo prevention system, an acoustic echo prevention method, and an acoustic echo prevention program for preventing, for example, acoustic echo and howling.

  Conventionally, when an application program for packet voice communication is used in an environment where a general-purpose personal computer (hereinafter abbreviated as a personal computer), a speaker, a microphone, and the like are appropriately combined and a headset, headphones, earphones, etc. are not used, After the audio sent from the end-talker's computer is output from the speaker connected to the far-end speaker's computer, it is picked up again by the microphone connected to the far-end speaker's computer Returning to the end speaker side causes a so-called acoustic echo, which makes speech difficult to hear and makes conversation difficult. In general, an acoustic echo canceller that performs arithmetic processing using special hardware on which a DSP is mounted is used as a means for preventing and removing acoustic echo and howling utterances that adversely affect calls.

  As this type of technology, for example, there is a method of estimating an echo signal (waveform) from an output audio signal using an adaptive filter and removing the echo signal from an input signal.

Here, Patent Document 1 discloses an echo suppression system in a situation where a fluctuation range of a network transmission delay amount when a VoIP application is used via the Internet is large. Patent Document 2 relates to a mute device of a digital communication device system. A method and device for canceling an acoustic echo caused by a sound signal that circulates from a counterpart's phone and becomes a return signal and is transmitted after being delayed. It is disclosed.
JP 2002-204187 A JP 2000-196493 A

  In the technique described in Patent Document 1, it is assumed that special hardware is used for both the VoIP application and the echo canceller, and the purpose is to use an application program for packet voice call on a general-purpose personal computer. Is more costly. In addition, since the acoustic echo that wraps around from the far-end talker side is canceled by the near-end talker side, when considering application to a packet voice call system, voice data packets that should be deleted flow over the network. There is redundancy such as.

  On the other hand, in the technique described in Patent Document 2, echoes that cannot be completely erased by the echo canceller in the main apparatus are suppressed by the mute control. It takes. Further, since the near-end speaker side performs acoustic echo cancellation and mute processing, when considering application to a packet voice communication system, there is a redundancy that a voice data packet to be deleted flows on the network. is there.

  In view of these points, a method of simply mounting the echo canceller itself on a general-purpose personal computer OS instead of a DSP can be adopted, but the numerical computation processing of the echo canceller is heavy and occupies a large amount of CPU resources. There is a risk of hindering other applications.

  An object of the present invention is to prevent acoustic echoes and the like with a simple configuration and low cost while reducing the processing load on the CPU without using special hardware.

  In order to achieve the above object, according to the first aspect of the present invention, communication with other acoustic echo prevention devices is possible via a network, voice input on the own device side during transmission, and other via a network There is provided an acoustic echo prevention device comprising an echo prevention function for on / off control of at least one of voice inputs on the acoustic echo prevention device side.

  In the second aspect of the present invention, in the first aspect, the echo prevention function is automatically detected by a signal related to the intention to transmit input by a manual operation of a user interface or a silence detection unit. There is provided an acoustic echo prevention apparatus characterized in that on / off control of the voice input is performed based on a signal related to the utterance state.

  In the third aspect of the present invention, communication with other acoustic echo prevention devices is possible via a network, and voice input on the other acoustic echo prevention devices side via the network is turned on / off during voice input on the own device side. It is provided with an echo prevention function for controlling on / off of voice input on its own device side according to control by the other acoustic echo prevention device at the time of voice input on the other acoustic echo prevention device side An acoustic echo prevention device is provided.

  According to a fourth aspect of the present invention, in the third aspect, the echo prevention function is a signal relating to the intention to transmit input by a manual operation of a user interface or an utterance automatically detected by a silence detection unit. There is provided an acoustic echo prevention apparatus that transmits and receives predetermined command information based on a signal related to a state and controls the voice input on / off based on the command information.

  In the fifth aspect of the present invention, communication with other acoustic echo prevention devices is possible via a network, and when the own device is not outputting voice data when the own device is inputting voice, There is provided an acoustic echo prevention device comprising an echo prevention function for on / off control of voice input on the acoustic echo prevention device side.

  In a sixth aspect of the present invention, in the fifth aspect, the echo prevention function is a signal relating to the intention to transmit input by a manual operation of a user interface or a speech automatically detected by a silence detection unit. By transmitting predetermined command information based on a signal relating to a state to another acoustic echo prevention device, the voice input on the other acoustic echo prevention device side is turned on / off. An acoustic echo prevention device is provided.

  In the seventh aspect of the present invention, when a voice packet can be communicated with a plurality of acoustic echo prevention devices via a network and a voice packet is received from one acoustic echo prevention device, the voice packet is analyzed, A centralized management device characterized in that predetermined control information based on the analysis result is sent out on the other acoustic echo prevention device side to turn on / off the voice input on the other acoustic echo prevention device side Provided.

  According to an eighth aspect of the present invention, there is provided an acoustic echo prevention method by a centralized management apparatus capable of communicating with a plurality of acoustic echo prevention apparatuses via a network, wherein the centralized management apparatus performs voice from one acoustic echo prevention apparatus side. When a packet is received, the voice packet is analyzed, and predetermined control information based on the result of the analysis is sent out on the other acoustic echo prevention apparatus side. An acoustic echo prevention method characterized by controlling on / off of an input is provided.

  According to a ninth aspect of the present invention, there is provided an acoustic echo prevention program by an acoustic echo prevention apparatus capable of communicating with another acoustic echo prevention apparatus via a network, wherein the acoustic echo prevention apparatus is configured to transmit a voice on its own device side during transmission. An acoustic echo prevention program is provided that executes an echo prevention function for controlling on / off of at least one of input and voice input on the other acoustic echo prevention apparatus side via a network.

  In a tenth aspect of the present invention, in the ninth aspect, the echo prevention function is automatically detected by a signal relating to the intention to transmit input by a manual operation of a user interface, or a silence detection unit. There is provided an acoustic echo prevention program characterized in that the voice input is controlled to be turned on / off based on a signal related to the utterance state.

  According to an eleventh aspect of the present invention, there is provided an acoustic echo prevention program by an acoustic echo prevention apparatus capable of communicating with another acoustic echo prevention apparatus via a network, wherein the acoustic echo prevention apparatus is connected to the network at the time of voice input on the own apparatus side. ON / OFF control of the voice input on the other acoustic echo prevention device side via the or when the voice input on the other acoustic echo prevention device side is turned on according to the control by the other acoustic echo prevention device An acoustic echo prevention program characterized by executing an echo prevention function for controlling on / off is provided.

  According to a twelfth aspect of the present invention, in the eleventh aspect, the echo prevention function is a signal relating to the intention to transmit input by a manual operation of a user interface or an utterance automatically detected by a silence detection unit. There is provided an acoustic echo prevention program characterized by transmitting / receiving predetermined command information based on a signal relating to a state and performing on / off control of the voice input based on the command information.

  According to a thirteenth aspect of the present invention, there is provided an acoustic echo prevention program by an acoustic echo prevention apparatus capable of communicating with another acoustic echo prevention apparatus via a network, wherein the acoustic echo prevention apparatus is configured to input a voice of its own device. An acoustic echo prevention program for executing an echo prevention function for on / off control of voice input on another acoustic echo prevention device side via a network when the own device is not outputting voice data Is provided.

  In a fourteenth aspect of the present invention, in the thirteenth aspect, the echo prevention function is a signal relating to a will to be transmitted input by a manual operation of a user interface or an utterance automatically detected by a silence detection unit. By transmitting predetermined command information based on a signal related to the state, the sound input is controlled to turn on / off the voice input based on the command information, and an acoustic echo prevention program is provided.

  According to the present invention, it is possible to prevent unnecessary packets from flowing out on the network while reducing the processing load of the CPU without using special hardware, and further, acoustic echoes and the like with a simple configuration and low cost. Acoustic echo prevention device, centralized management device, acoustic echo prevention system, acoustic echo prevention method, and acoustic echo prevention program can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a conceptual diagram common to the acoustic echo prevention apparatus and acoustic echo prevention system according to the first to fourth embodiments of the present invention, and will be described in detail.

  As shown in FIG. 1, the acoustic echo prevention apparatus 1 is provided with an application program 3 for packet voice call. Further, the acoustic echo prevention apparatus 1 includes a network interface 2 for communication, a user interface 6 conceptually including an operation member for performing various controls and a display unit such as a display, and a user for communicating with the user interface 6. It has an interface module 4, a sound device 5 for controlling input / output of audio signals, a microphone 7 for receiving audio input, a speaker 8 for outputting audio, and the like.

  The installed application program 3 includes a packet processing unit 3a for analyzing packets, an echo prevention module 3b for preventing acoustic echo, a codec 3c including a digital encoder and a decoder, and the like. ing. Furthermore, the acoustic echo prevention apparatus 1 has a control channel (connection) for mute control in addition to an audio channel (connection) that can be controlled based on the application program 3.

  The user interface 6 also includes various drawing means such as a drawing lamp and a physical lamp (LED, etc.) on the display device for notifying the state of the device (whether or not a call is possible), and various input means such as a mouse and keyboard. Of course, it is included above.

  In such a configuration, the acoustic echo prevention device 1 does not perform arithmetic processing using special hardware such as a DSP, and performs processing based on the application program 3 for packet voice call, and the network interface 2 or the like. Acoustic echoes are prevented by controlling on / off the voice input at the near-end side, the far-end side, or both acoustic echo prevention devices via the illustrated network. The echo prevention function described in the claims is a function realized by the application program 3 for packet voice call.

  Hereinafter, each embodiment will be described in detail based on the above characteristics.

(First embodiment: local control system)
FIG. 2 shows the configuration of the acoustic echo prevention apparatus and acoustic echo prevention system according to the first embodiment of the present invention, which will be described in detail.

  As shown in FIG. 2, the acoustic echo prevention apparatus 11 is provided with an application program 111 for packet voice call, and the application program 111 includes a mute function 112. Furthermore, a speaker 113, a user interface 114, and a microphone 115 are connected to the acoustic echo prevention device 11.

  Similarly, the acoustic echo prevention apparatus 12 is provided with an application program 121 for packet voice call, and the application program 121 includes a mute function 122. Furthermore, a speaker 123, a user interface 124, and a microphone 125 are connected to the acoustic echo prevention device 12. The user interfaces 114 and 124 conceptually include a display unit indicating whether voice input is possible or the like, a display unit such as an LED, and operation members such as a mouse and a switch for inputting a voice transmission intention during manual operation.

  And both are connected via the network 13 so that communication is possible, and the acoustic echo prevention system is comprised by this. The acoustic echo prevention system has a voice channel (connection) that can be controlled based on application programs 111 and 121 for packet voice call. Here, only the two acoustic echo prevention devices 11 and 12 are illustrated, but it is needless to say that connection (communication) with further acoustic echo prevention devices is possible.

  In addition to the configuration described above, the acoustic echo prevention devices 11 and 12 include the network interface 2, the user interface module 4, the sound device 5, etc. as described above with reference to FIG. In the following, the same components as those in FIG. 1 will be described using the same reference numerals.

  FIG. 3 shows in detail the manual function of the echo prevention module included in the application program 121 for packet voice call.

  The application program 111 has the following functions as well.

  The packet voice call application program 121 includes a voice input processing unit 121a, a voice input control unit 121b, and a voice output processing unit 121c as an echo prevention module. When receiving the input of audio data from the sound device 5, the audio input processing unit 121a outputs transmission audio data Pa to the packet processing unit 3a. The audio output processing unit 121 c receives the received audio data Pb from the packet processing unit 3 a and outputs the audio data to the sound device 5. The voice input control unit 121b receives user interface input flag data Ia from the user interface module 4 or outputs user interface output flag data Od to the user interface module 4.

  When the voice input control unit 121b receives the user interface input flag data Ia from the user interface module 4, the voice input control unit 121b controls the voice input processing based on the voice output state flag data Ib from the voice output processing unit 121c. The flag data Oe is output to the voice input processing unit 121a. The voice input processing unit 121a controls the mute of voice input on / off based on the voice input process control flag data Oe. In addition, the voice input control unit 121b outputs user interface output flag data Od to the user interface module 4, and controls display on the display unit. In the manual operation, the mute function 122 in FIG. 2 is realized by the above functions of the audio input processing unit 121a, the audio input control unit 121b, and the audio output processing unit 121c.

  Hereinafter, with reference to the flowchart of FIG. 4, the manual operation on the acoustic echo prevention apparatus 12 side will be described in detail. In the initial state, the voice input processing unit 121a is muted (disabled) (voice input processing control flag data Oe = OFF), and that the voice input is prohibited (speech transmission disabled state display) is displayed on the user interface. 124 (user interface output flag data Od = OFF) (step S1).

  Under such a state, the user manually operates the operation member of the user interface 124 to transmit a voice transmission intention to the acoustic echo prevention apparatus 12 (step S2).

  In this step S2, when the voice transmission intention is indicated by the user, user interface input flag data Ia (= ON) is input to the voice input control unit 121b.

  Subsequently, the voice input control unit 121b determines whether or not the acoustic echo prevention device 12 itself is outputting voice data based on the voice output state flag data Ib (step S3). In step S3, when the audio data is being output (audio output state flag data Ib = ON), the audio input control unit 121b holds the audio input processing unit 121a muted (disabled), and Control is performed so that the voice transmission impossible display is continuously displayed on the display unit. In this case, since the state only needs to be maintained, the voice input processing control flag data Oe is not transmitted to the voice input processing unit 121a, and the user interface output flag data Od is not transmitted to the user interface module 4.

  On the other hand, when it is determined that voice data is not being output when the user's voice transmission intention is input, the voice input control unit 121b cancels (enables) the mute of the voice input processing unit 121a to In addition to enabling input, control is performed so that the voice transmission enabled state display is displayed on the display unit of the user interface 124 instead of the voice transmission disabled state display (step S4). In this case, the voice input control unit 121b transmits the voice input processing control flag data Oe (= ON) to the voice input processing unit 121a, and transmits the user interface output flag data Od (= ON) to the user interface module 4.

  Subsequently, the voice input control unit 121b determines based on the user interface input flag data Ia whether or not the user has manually operated the operation member of the user interface 124 and the voice transmission intention is continuously desired. (Step S5).

  In step S5, when the voice transmission intention is not continued (user interface input flag data Ia = OFF), the voice input control unit 121b mutes (disables) the voice input processing unit 121a (step S6). . In this case, the voice input control unit 121b transmits voice input processing control flag data Oe (= OFF) to the voice input processing unit 121a. User interface output flag data Od (= OFF) is transmitted to the user interface module 4. The series of processing described above is performed independently by the far-end and near-end acoustic echo prevention devices 11 and 12, thereby preventing acoustic echo.

  FIG. 5 shows in detail the automatic function of the echo prevention module of the application program 126 for packet voice call. Here, it demonstrates centering on difference with FIG.

  The difference from the configuration of FIG. 3 described above is that a silence detection processing unit 126d is provided. In the manual configuration described above, it is necessary for the user to operate the operation unit of the user interface 124 to transmit the voice transmission intention. However, in this automatic configuration, the operation of the operation unit is not necessary, and silence detection is performed. The processing unit 126d automatically detects a silent state, and thereby performs an equivalent process.

  That is, when voice data is input from the sound device 5 to the voice input processing unit 126a, the transmission voice data Pa is sent from the voice input processing unit 126a to the silence detection processing unit 126d. When the silence detection processing unit 126d detects a silence state, the silence detection processing unit 126d transmits the silence detection state flag data Ic to the voice input control unit 126b at a predetermined timing.

  On the other hand, when the received audio data Pb is input to the audio output processing unit 126c, the audio output processing unit 126c transmits the audio output state flag data Ib to the audio input control unit 126b. When the voice input control unit 126b receives the silent detection state flag data Ic, the voice input control unit 126b detects the state of the voice output state flag data Ib, and based on the result, the voice input processing control flag data Oe is detected by the silence detection processing unit 126d. Send to. When the silent detection processing unit 126d receives the voice input processing control flag data Oe (= OFF), it mutes (disables) the voice input. At this time, the transmission voice data is discarded without being sent to the packet processing unit 3a. The same applies to voice data.

  Further, the silence detection processing unit 126d cancels (enables) the mute of the voice input when receiving the voice input process control flag data Oe (= ON).

  The voice input control unit 126b outputs user interface output flag data Od according to the state of the silence detection state flag data Ic and the voice output state flag data Ib, and appropriately switches the display on the display unit of the user interface 124. Control.

  2 is realized by the silence detection processing unit 126d, the audio input control unit 126b, and the audio output processing unit 126c.

  Hereinafter, the automatic operation on the acoustic echo prevention apparatus 12 side will be described in detail with reference to the flowchart of FIG. Here, it demonstrates centering on difference with FIG.

  In step S2 of FIG. 4, the user transmits the intention of voice transmission to the acoustic echo prevention device 22 by manually operating the operation member of the user interface 6, but in step S12 of FIG. 6, the silence detection processing unit 126d. However, by sending the silence detection state flag data Ic to the voice input control unit 126b, the voice input control unit 126b is notified of the presence or absence of voice data.

  In step S5 in FIG. 4, the voice input control unit 121b determines whether the user interface input flag data Ia (= On) is held, that is, whether the voice transmission intention is continued, and is continued. In this case, the voice input is continued. In step S15 of FIG. 6, the voice input control unit 126b determines the continuation of the voice transmission intention based on the silence detection state flag data Ic. Note that steps S11, S13, S14, and S16 in FIG. 6 are the same as steps S1, S3, S4, and S6 in FIG.

  As described above, according to the first embodiment of the present invention, acoustic echo and howling in each acoustic echo prevention device can be simplified by independent control by the acoustic echo prevention device constituting the acoustic echo prevention system. With a simple configuration, it can be efficiently prevented.

(Second embodiment: mutual remote control system)
FIG. 7 shows and describes the configuration of an acoustic echo prevention apparatus and system according to the second embodiment of the present invention. Here, it demonstrates centering on difference with 1st Embodiment (FIG. 2).

  As shown in FIG. 7, application programs 211 and 221 for packet voice calls are installed in the acoustic echo prevention apparatuses 21 and 22, respectively, and the programs 211 and 221 include mute functions 212 and 222. It is. These mute functions 212 and 222 can be controlled by the other acoustic echo prevention device. For example, if the control target is a far-end acoustic echo prevention device, the mute function of the far-end acoustic echo prevention device can be controlled by the near-end acoustic echo prevention device.

  That is, when the user manually transmits the voice transmission intention by operating the operation member of the user interface on the one acoustic echo prevention device side or when the voice input by the user is automatically detected, When it is determined that the output is not in progress, one acoustic echo prevention device transmits a command packet to mute (disable) the voice input of the acoustic echo prevention device at the other end. In order to realize this, this acoustic echo prevention system has a channel for mute control (connection) in addition to a sound channel (connection) that can be controlled by the application programs 211 and 221. As described above with reference to FIG. 1, the acoustic echo prevention devices 21 and 22 include the network interface 2, the user interface module 4, the sound device 5, and the like. The description of the elements will be made using the same reference numerals.

  FIG. 8 shows in detail the manual function of the echo prevention module included in the application program 221 for packet voice call. The following functions are also provided for the application program 211 in the same manner.

  The application program 221 for packet voice call has a voice input processing unit 221a, a voice input control unit 221b, and a voice output processing unit 221c as an echo prevention module. The audio input processing unit 221a receives input of audio data from the sound device 5, and outputs transmission audio data Pa to the packet processing unit 3a. The audio output processing unit 221c receives the received audio data Pb from the packet processing unit 3a and outputs the audio data to the sound device 5. The voice input control unit 221 b receives user interface input flag data Ia from the user interface module 4 or outputs user interface output flag data Od to the user interface module 4.

  When the audio input control unit 221b receives the user interface input flag data Ia, the audio input control unit 221b transmits a transmission control signal Sa for muting (disabling) the audio input of another acoustic echo prevention device. In addition, when receiving the reception control signal Sb from another acoustic echo prevention device, the voice input control unit 221b outputs the voice input processing control flag data Oe to the voice input processing unit 221a, and performs the voice input processing. The part 221a is muted (disabled). In this case, the output of the transmission audio data Pa is stopped. Further, the voice input control unit 221b switches the display by outputting the user interface output flag data Od to the user interface module 4. At the time of manual operation, the mute function 222 of FIG. 7 is realized by the audio input processing unit 221a and the audio input control unit 221b.

  The operation of the above configuration will be described below with reference to the flowchart of FIG.

  FIG. 9A shows a manual process of muting (disabling) the voice input of the far-end acoustic echo prevention device by the near-end acoustic echo prevention device. Here, the near-end side will be described as the acoustic echo prevention device 22, and the far-end side will be described as the acoustic echo prevention device 21.

  In the initial state, the voice input processing unit 221a of the near-end acoustic echo prevention device 22 is unmuted (enabled) (voice input processing control flag data Oe = ON), and the voice transmission disabled state display is displayed by the user. It is displayed on the display unit of the interface 6 (user interface output flag data Od = OFF) (step S21). Under such a condition, the user manually operates the operation member of the user interface 224 to transmit the voice transmission intention to the acoustic echo prevention device 22 (step S22). This voice transmission intention is input to the voice input control unit 221b as user interface input flag data Ia (= ON). The voice input control unit 221b determines whether or not the voice input of the near-end acoustic echo prevention device 22 is muted (disabled) (step S23).

  If the voice input is muted (disabled) in step S23, the voice input control unit 221b holds the voice input processing unit 221a muted (disabled) and displays a voice transmission disabled indication. Control to display continuously on the screen.

  On the other hand, when the mute of the sound input of the near-end acoustic echo prevention device 22 is canceled (enabled) in step S23, the sound input control unit 221b performs the sound input of the far-end acoustic echo prevention device 21. A transmission control signal Sa for muting (disabling) is transmitted to the packet processing unit 3a. The transmission control signal Sa is sent as a command packet by the packet processing unit 3a and sent to the far-end acoustic echo prevention device 21 (step S24).

  Subsequently, the voice input control unit 221b of the near-end acoustic echo prevention device 22 determines whether or not an ACK is received from the far-end acoustic echo prevention device 21 within the timer time (step S25). This is to prevent deadlock when both parties intend to transmit at the same time and to prevent both sides from being muted at the same time. Here, if no ACK is received, it is also assumed that the command packet has not been transmitted to the far-end acoustic echo prevention device 21, so the process returns to step S22 and the above operation is repeated. On the other hand, when ACK is received, the voice input control unit 221b transmits user interface input flag data Ia (= ON), and displays a voice transmission enabled state display on the display unit of the user interface 224 (step S26). .

  Subsequently, the voice input control unit 221b determines whether or not the user interface input flag data Ia (= ON) is held, that is, whether or not the voice transmission intention is continued. Continue (step S27). When the user interface input flag data Ia (= OFF) is received, the transmission control signal Sa for instructing the far-end acoustic echo prevention device 21 to cancel (enable) the audio input mute is transmitted. This transmission control signal Sa is sent as a command packet by the packet processing unit 3a and sent to the far-end acoustic echo prevention device 21. Further, the voice input control unit 221b outputs user interface input flag data Ia (= OFF), and displays a voice transmission impossible state display on the display unit of the user interface 224 (step S28). By performing the above control with both the far-end and near-end acoustic echo prevention devices, acoustic echo is effectively prevented.

  FIG. 9B shows a manual process in which the sound input of the near-end acoustic echo prevention device is muted (disabled) by the far-end acoustic echo prevention device. Here, the description will be made with the near-end side positioned as the acoustic echo prevention device 22 and the far-end side positioned as the acoustic echo prevention device 21.

  The initial state is the same as in FIG. Under such a condition, when the near-end acoustic echo prevention device 22 receives a command packet for muting (disabling) the voice input from the far-end acoustic echo prevention device 21, the packet processing unit 3a receives the command packet. The command packet is analyzed. The voice input control unit 221b is in a standby state until the reception control signal Sb is sent. When this reception control signal Sb is received (step S29), it is determined whether or not it is in an ACK waiting state (step S30). If it is not in an ACK waiting state, the voice input of the acoustic echo prevention device 22 on the near end side is input. Mute (disable) (step S31), transmit ACK to the far-end acoustic echo prevention device 21 (step S32), and return to step S29.

  FIG. 9C shows a process of canceling (enabling) the audio input of the near-end acoustic echo prevention device by the far-end acoustic echo prevention device. Here, the description will be made with the near-end side positioned as the acoustic echo prevention device 22 and the far-end side positioned as the acoustic echo prevention device 21.

  The initial state is the same as in FIG. In this state, when the near-end acoustic echo prevention device 22 receives from the far-end acoustic echo prevention device 21 a command packet for canceling (enabling) audio input, the packet processing unit 3a The command packet is analyzed at. The voice input control unit 221b is in a standby state until the reception control signal Sb is sent. When the reception control signal Sb is received (step S33), the audio input of the near-end acoustic echo prevention device 22 is unmuted (enabled) (step S34), and the process returns to step S33.

  Next, FIG. 10 shows in detail and shows the automatic function of the echo prevention module included in the application program 226 for packet voice call. The following functions are provided for the application program 216 as well.

  Here, the difference from the configuration in FIG. 8 will be mainly described.

  The difference from the configuration of FIG. 8 described above is that a silence detection processing unit 226d is provided. In the manual configuration described above, it is necessary for the user to operate the operation unit of the user interface 224 to convey the voice transmission intention. However, in this automatic configuration, the operation of the operation unit is not necessary, and silence detection is performed. The processing unit 226d automatically detects a silent state, and thereby performs an equivalent process.

  That is, when voice data is input from the sound device 5 to the voice input processing unit 226a, the transmission voice data is sent from the voice input processing unit 226a to the silence detection processing unit 226d. On the other hand, when the silence detection processing unit 226d detects the silence state, the silence detection processing unit 226d transmits the silence detection state flag data Ic to the voice input control unit 226b. Further, when the received audio data is input to the audio output processing unit 226c, the audio output processing unit 226c transmits the audio output state flag data Ib to the audio input control unit 226b.

  When receiving the reception control signal Sb, the voice input control unit 226b transmits the voice input processing control flag data Oe to the silence detection processing unit 226d based on the result. When receiving the voice input processing control flag data Oe, the silence detection processing unit 226d discards the transmission voice data without sending it to the packet processing unit 3a. Further, when receiving the reception control signal Sb, the voice input control unit 226b appropriately switches the display on the display unit of the user interface 224.

  In the automatic mode, the mute function 222 of FIG. 7 is realized by the silence detection processing unit 226d and the audio input control unit 226b.

  Hereinafter, with reference to the flowchart of FIG. 11, a description will be given of automatic processing for muting (disabling) the voice input of the far-end acoustic echo prevention device by the near-end acoustic echo prevention device. Here, it demonstrates centering on difference with Fig.9 (a).

  It should be noted that manual processing for muting (disabling) the voice input of the near-end acoustic echo prevention device by the far-end acoustic echo prevention device, and near-end acoustic echo prevention by the far-end acoustic echo prevention device The process for canceling (enabling) muting the audio input of the apparatus is the same as that shown in FIGS. 9B and 9C described above, and a duplicate description is omitted here.

  In the process of FIG. 9A, in step S22, the user manually operates the operation member of the user interface 6 to inform the acoustic echo prevention apparatus 22 of the intention of voice transmission. In this process, the silence detection processing unit 226d sends the silence detection state flag data Ic to the voice input control unit 226b, thereby notifying the voice input control unit 226b of the presence or absence of voice data (step S42).

  In the process of FIG. 9A, in step S27, the voice input control unit 221b determines whether the user interface input flag data Ia (= ON) is held, that is, whether the voice transmission intention is continued. In the process of FIG. 11, the voice input control unit 226b determines the continuation of the voice transmission intention based on the silence detection state flag data Ic. S47).

  Steps S41, S43 to S46, and S48 are the same as steps S21, S23 to S26, and S28 of FIG.

  As described above, according to the second embodiment of the present invention, both the far-end side and near-end side acoustic echo prevention devices mutually turn on / off the mute function of the communication partner. Acoustic echo, howling, etc. can be effectively prevented.

(Third embodiment: floor control system)
FIG. 12 shows and describes the configuration of an acoustic echo prevention apparatus and system according to the third embodiment of the present invention. Here, it demonstrates centering on difference with 1st Embodiment (FIG. 2).

  As shown in FIG. 12, application programs 311 and 321 for packet voice communication are installed in the acoustic echo prevention devices 31 and 32, respectively, and the programs 311 and 321 include mute functions 312 and 322, respectively. ing. The mute functions 312 and 322 can be controlled by a specific acoustic echo prevention device.

  Now, the acoustic echo prevention device 32 is positioned on the near end side, and the acoustic echo prevention device 31 is positioned on the far end side. Under such a relationship, when the user's intention to transmit is input to the near-end acoustic echo prevention device 32, the voice input to the far-end acoustic echo prevention device 31 is performed only when the voice data is not being output. A command packet for mute (disable) is transmitted, and the mute of the sound input of the acoustic echo prevention device 32 on the near end side is released (enabled). At the same time, a voice transmission enabled state display is displayed on the display unit of the user interface 324.

  When the input of the user's intention to transmit to the near-end acoustic echo prevention device 32 is completed, a command packet for unmuting (enabling) the voice input of the far-end acoustic echo prevention device 31 is transmitted. The voice input impossible state is displayed on the display unit of the user interface 324 at the same time as the voice input on the end side is disabled. These controls are unilaterally controlled by the far-end or near-end application software to prevent acoustic echo and howling.

  In order to realize the above, the acoustic echo prevention devices 31 and 32 have audio channels (connections) that can be controlled by the application programs 311 and 321 and channels (connections) for mute control. As described above with reference to FIG. 1, each of the acoustic echo prevention devices 31 and 32 includes the network interface 2, the user interface module 4, the sound device 5, and the like. The same constituent elements will be described using the same reference numerals.

  FIG. 13 shows in detail the manual function of the echo prevention module included in the application program 321 for packet voice call.

  The packet voice call application program 321 includes a voice input processing unit 321a, a voice input control unit 321b, and a voice output processing unit 321c as an echo prevention module. The audio input processing unit 321a receives input of audio data from the sound device 5, and outputs transmission audio data Pa to the packet processing unit 3a. The audio output unit 321 c receives the received audio data Pb from the packet processing unit 3 a and outputs the audio data to the sound device 5. The voice input control unit 321 b receives user interface input flag data Ia from the user interface module 4 or outputs user interface output flag data Od to the user interface module 4.

  When receiving the user interface input flag data Ia, the voice input control unit 321b transmits a transmission control signal Sa for muting the voice input to the other acoustic echo prevention device. Further, when receiving the reception control signal Sb from the other acoustic echo prevention device, the voice input control unit 321b detects the state of the voice output state flag data Ib, and controls voice input processing based on the result. The flag data Oe is output to the voice input processing unit 321a, and the user interface flag data Od is output to the user interface module 4 while controlling the voice input processing unit 321a to stop the output of the transmission voice data Pa.

  During manual operation, the mute function 322 in FIG. 12 is realized by the audio input processing unit 321a and the audio input control unit 321b.

  Hereinafter, the operation of the above configuration will be described with reference to the flowchart of FIG.

  FIG. 14A shows a manual process in which the sound input of the far-end acoustic echo prevention device 31 is muted (disabled) by the near-end acoustic echo prevention device 32.

  In the initial state, the voice input processing unit 321a of the near-end acoustic echo prevention device 32 is muted (disabled) (voice input processing control flag data Oe = OFF), and the voice transmission disabled state display is displayed on the user interface. It is displayed on the display unit 324 (user interface output flag data Od = OFF) (step S60).

  Under such a state, the user manually operates the operation member of the user interface 324 to inform the acoustic echo prevention apparatus 32 of the intention of voice transmission (step S61).

  When the user indicates the voice transmission intention, the user interface input flag data Ia is input to the voice input control unit 321b. The voice input control unit 321b sends a transmission control signal Sa for muting (disabling) the voice input of the acoustic echo prevention device 31 on the far end side. The transmission control signal Sa is converted into a command packet by the packet processing unit 3a, and then transmitted to the far-end acoustic echo prevention device 31. Further, the voice input control unit 321b cancels (enables) the mute of the voice input processing unit 321a to enable input of voice data, and displays a voice transmission enabled state display instead of the voice transmission disabled state display. Control is performed to display on the display unit of the user interface 324 (step S63).

  The transmission control signal Sa may be transmitted when a sound signal from the acoustic echo prevention device 31 on the far end side is detected by the acoustic echo prevention signal 32 on the near end side. For the detection of the sound signal, a method using the silence detection processing unit used in the present invention can be considered, but it is needless to say that the present invention is not limited to this.

  In this case, the voice input control unit 321b sends the voice input processing control flag data Oe (= ON) to the voice input processing unit 321a, and sends the user interface output flag data Od (= ON) to the user interface module 4.

  Subsequently, the voice input control unit 321b determines, based on the user interface input flag data Ia, whether or not the voice transmission intention is continuously desired by manually operating the operation member of the user interface 324 by the user. (Step S64).

  In step S64, when the voice transmission intention is not continuously transmitted, that is, when the input of the user's voice transmission intention is completed, the voice input control unit 321b performs acoustic echo prevention on the far end side. A transmission control signal Sa for releasing (enabling) muting of the audio input of the device 31 is transmitted. The transmission control signal Sa is converted into a command packet by the packet processing unit 3a, and then transmitted to the far-end acoustic echo prevention device 31. Further, the voice input control unit 321b mutes (disables) the voice input processing unit 321a, and displays a transmission impossible state display on the display unit (step S65). In this case, the voice input control unit 321b sends the voice input processing control flag data Oe (= OFF) to the voice input processing unit 321a, and sends the user interface output flag data Od (= OFF) to the user interface module 4. To do. The above-described series of processing is performed by the near-end acoustic echo prevention device 32, thereby effectively preventing acoustic echo.

  FIG. 14B shows a manual process in which the sound input of the far-end acoustic echo prevention device 31 is muted (disabled) by the near-end acoustic echo prevention device 32.

  The function of the echo prevention module in the application program 311 mounted on the far-end acoustic echo prevention device 31 is the same as that shown in FIG. The description will be made with appropriate reference with reference numerals.

  In the initial state, the voice input processing unit 321a of the far-end acoustic echo prevention device 31 is unmuted (enabled) (voice input processing control flag data Oe = ON), and the voice transmission enabled state display is the user interface 314. (User interface output flag data Od = ON) (step S66).

  In this state, when the far-end acoustic echo prevention device 31 receives a command packet for muting (disabling) voice input from the near-end acoustic echo prevention device 32, the packet processing unit 3a receives the command packet. The instruction packet is analyzed, and the standby state is kept until the reception control signal Sb is sent to the voice input control unit 321b. When the voice input control unit 321b receives the reception control signal Sb (step S67), the voice input is muted (disabled), and control is performed so as to display a voice transmission impossible state display on the display unit (step S68). In this case, the voice input control unit 321b sends the voice input processing control flag data Oe (= OFF) to the voice input processing unit 321a, and sends the user interface output flag data Od (= OFF) to the user interface module 4. Will do.

  FIG. 14C shows a manual process in which the sound input of the far-end acoustic echo prevention device 31 is unmuted (enabled) by the near-end acoustic echo prevention device 32.

  The function of the echo prevention module in the application program 311 mounted on the far-end acoustic echo prevention device 31 is the same as that shown in FIG. The description will be made with appropriate reference with reference numerals.

  When the far-end acoustic echo prevention device 31 receives the reception control signal Sb from the near-end acoustic echo prevention device 32 under the state of the branch point between steps S66 and S67 in FIG. In step S70, the audio input of the acoustic echo prevention device 31 on the near end side is released (enabled), and a voice transmission enabled state is displayed on the display unit of the user interface 314 (step S71).

  In this case, the voice input control unit 321b transmits the voice input processing control flag data Oe (= ON) to the voice input processing unit 321a, and sends the user interface output flag data Od (= ON) to the user interface module 4. Send to.

  Next, FIG. 15 shows in detail the automatic function of the echo prevention module included in the application program 326 for packet voice call.

  Here, the difference from the configuration in FIG. 13 will be mainly described.

  The difference from the configuration of FIG. 13 described above is that a silence detection processing unit 326d is provided. In the manual configuration described above, it is necessary for the user to operate the operation unit of the user interface 324 to convey the voice transmission intention. However, in this automatic configuration, the operation unit is not required to be operated, and the silence detection is performed. The processing unit 326d automatically detects a silence state, and thereby performs an equivalent process.

  That is, when voice data is input from the sound device 5 to the voice input processing unit 326a, transmission voice data is sent from the voice input processing unit 326a to the silence detection processing unit 326d. On the other hand, if the silence detection processing unit 326d detects a silence state, the silence detection processing unit 326d transmits the silence detection state flag data Ic to the voice input control unit 326b and discards the silence data. Further, when the received voice data is input to the voice output processing unit 326c, the voice output processing unit 326c transmits the voice output state flag data Ib to the voice input control unit 326b.

  When receiving the reception control signal Sb, the voice input control unit 326b detects the state of the voice output state flag data Ib, and transmits the voice input processing control flag data Oe to the silence detection processing unit 326d based on the result. When receiving the voice input processing control flag data Oe, the silence detection processing unit 326d discards the transmission voice data without sending it to the packet processing unit 3a. In addition, when the reception control signal Sb is received, the voice input control unit 326b appropriately switches the display on the display unit of the user interface 6.

  In the automatic mode, the mute function 322 in FIG. 12 is realized by the silence detection processing unit 326d and the voice input control unit 326b.

  Hereinafter, a process of muting (disabling) the voice input of the far-end acoustic echo prevention device by the near-end acoustic echo prevention device will be described with reference to the flowchart of FIG.

  Here, it demonstrates centering on difference with Fig.14 (a).

  As described above, in the process of FIG. 14A, in step S61, the user has manually communicated the operation member of the user interface 324 to inform the acoustic echo prevention device 32 of the intention of voice transmission. In the process of FIG. 16, the silence detection processing unit 326d sends the silence detection state flag data Ic to the voice input control unit 326b to notify the voice input control unit 326b of the presence or absence of voice data (step S72).

  14A, in step S64, the voice input control unit 321b determines whether the user interface input flag data Ia (= On) is held, that is, whether the voice transmission intention is continued. In the process of FIG. 16, the voice input control unit 326b determines the continuation of the voice transmission intention based on the silence detection state flag data Ic. S75).

  In addition, Steps S71, S73, S74, and S76 are the same as Steps S60, S62, S63, and S65 in FIG.

  The automatic processing for muting (disabling) the sound input of the far-end acoustic echo prevention device 31 by the near-end acoustic echo prevention device 32 is the same as that shown in FIG. The automatic processing for canceling (enabling) the sound input of the far-end acoustic echo prevention device 31 by the acoustic echo prevention device 32 is the same as in FIG.

  As described above, according to the third embodiment of the present invention, the acoustic echo is controlled by centrally controlling on / off of the mute functions of the plurality of acoustic echo prevention devices by the near-end acoustic echo prevention device. And howling can be effectively prevented.

(Fourth embodiment: centralized control method)
In FIG. 17, the structure of the acoustic echo prevention system based on the 4th Embodiment of this invention is shown and demonstrated. As shown in the figure, the centralized management device 43 is connected to the acoustic echo prevention devices 41 and 44 through a network 42 so as to be able to communicate. Here, only the two acoustic echo prevention devices 41 and 44 are shown, but communication with a plurality of devices is possible. The centralized management apparatus 43 has an echo prevention control application program 431 installed therein.

  Hereinafter, the function of the program 431 will be briefly described with reference to FIG.

  The program 431 includes packet analysis processing units 431a and 431c and an echo prevention packet transmission unit 431b as functions. In such a configuration, when receiving the voice packet transmitted from one acoustic echo prevention device, the packet analysis processing units 431a and 431c analyze the packet and send the result to the echo prevention packet transmission unit 431b. . The echo prevention packet transmission unit 431b transmits a control packet to the acoustic echo prevention apparatus that is the transmission destination of the packet. This control packet controls the mute functions 411 and 441 of the acoustic echo prevention device. Upon receiving this control packet, the destination acoustic echo prevention apparatus mutes (disables) the voice input.

  Then, the echo prevention packet transmission unit 431b transmits the control packet to the acoustic echo prevention apparatus again at a predetermined timing such as after a predetermined time has elapsed. The destination acoustic echo prevention device cancels (enables) the mute of the audio input based on the control packet. In this way, unnecessary voice packets are prevented from flowing out on the network.

  As described above, according to the fourth embodiment of the present invention, acoustic echo and howling in a plurality of acoustic echo prevention devices are effectively prevented by a centralized management device independent of the acoustic echo prevention device. Can do.

  The first to fourth embodiments of the present invention have been described above. However, the present invention is not limited to this, and various modifications and changes can be made without departing from the spirit of the present invention. is there. For example, in the above embodiment, an example of an acoustic echo prevention device has been shown. However, application software for packet voice calls having various features as described above is installed in a general-purpose personal computer and started on the OS. By doing so, it is possible to easily realize the above processing. In the above description, “silence” means not only a state in which no sound is output, but also a state in which only sound output below a predetermined threshold is being output.

The conceptual diagram common to the acoustic echo prevention apparatus and acoustic echo prevention system which concern on the 1st thru | or 4th embodiment of this invention. The figure which shows the structure of the acoustic echo prevention apparatus which concerns on the 1st Embodiment of this invention, and an acoustic echo prevention system. The figure which shows the function at the time of the manual operation of the echo prevention module contained in the application program for packet voice calls mounted in the acoustic echo prevention apparatus which concerns on the 1st Embodiment of this invention. The flowchart explaining the operation | movement at the time of the manual operation of the acoustic echo prevention apparatus which concerns on the 1st Embodiment of this invention. The figure which shows the function at the time of the automatic of the echo prevention module of the application program for packet voice calls mounted in the acoustic echo prevention apparatus which concerns on the 1st Embodiment of this invention. The flowchart explaining the operation | movement at the time of the automatic at the acoustic echo prevention apparatus side which concerns on the 1st Embodiment of this invention in detail. The figure which shows the structure of the acoustic echo prevention apparatus which concerns on the 2nd Embodiment of this invention, and an acoustic echo prevention system. The figure which shows the function at the time of the manual operation of the echo prevention module contained in the application program for packet voice calls mounted in the acoustic echo prevention apparatus which concerns on the 2nd Embodiment of this invention. (A) is a flowchart showing a manual process for muting the voice input of the far-end acoustic echo prevention apparatus, and (b) shows a manual process for muting the voice input of the near-end acoustic echo prevention apparatus. The flowchart, (c) is a flowchart showing a process of canceling the mute of the voice input of the near-end acoustic echo prevention apparatus. The automatic function of the echo prevention module included in the application program for packet voice communication implemented in the acoustic echo prevention apparatus according to the second embodiment of the present invention will be shown and described in detail. The flowchart which shows the process at the time of automatic which mutes the audio | voice input of the far-end acoustic echo prevention apparatus by the near-end acoustic echo prevention apparatus in the 2nd Embodiment of this invention. The figure which shows the structure of the acoustic echo prevention apparatus which concerns on the 3rd Embodiment of this invention, and an acoustic echo prevention system. The figure which shows the function at the time of the manual operation of the echo prevention module contained in the application program for packet voice calls implemented in the acoustic echo prevention apparatus which concerns on the 3rd Embodiment of this invention. (A) is a flowchart showing a manual process for muting the voice input of the far-end acoustic echo prevention device by the near-end acoustic echo prevention device, and (b) is a far-end acoustic echo prevention device by the near-end acoustic echo prevention device. The flowchart which shows the process at the time of the manual which mutes the audio | voice input of the side acoustic echo prevention apparatus, (c) is the manual time which cancels | releases the audio | voice input of the far-end acoustic echo prevention apparatus by the near-end acoustic echo prevention apparatus The flowchart which shows the process of. The automatic function of the echo prevention module included in the application program for packet voice communication implemented in the acoustic echo prevention apparatus according to the third embodiment of the present invention will be shown and described in detail. The flowchart which shows the process which mutes the audio | voice input of the acoustic echo prevention apparatus of a far end by the acoustic echo prevention apparatus of a near end in the 3rd Embodiment of this invention. The figure which shows the structure of the acoustic echo prevention apparatus which concerns on the 4th Embodiment of this invention, and an acoustic echo prevention system. The conceptual diagram for demonstrating the function of the program mounted in the centralized management apparatus of the acoustic echo prevention system which concerns on the 4th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Acoustic echo prevention apparatus, 2 ... Network interface, 3 ... Application program, 3a ... Packet processing part, 3b ... Echo prevention module, 3c ... Codec, 4 ... User Interface module, 5 ... sound device, 6 ... user interface, 7 ... microphone, 8 ... speaker.

Claims (14)

It can communicate with other acoustic echo prevention devices via the network,
An acoustic echo comprising an echo prevention function for on / off control of at least one of the voice input on the own device side and the voice input on the other acoustic echo prevention device side via a network during transmission Prevention device.   The echo prevention function is an on / off control of the voice input based on a signal related to the intention to transmit input by manual operation of the user interface or a signal related to the utterance state automatically detected by the silence detection unit. The acoustic echo prevention device according to claim 1, wherein: It can communicate with other acoustic echo prevention devices via the network,
On / off control of voice input on the other acoustic echo prevention device side via the network at the time of voice input on the own device side, or according to control by the other acoustic echo prevention device at the time of voice input on the other acoustic echo prevention device side An acoustic echo prevention apparatus comprising an echo prevention function for controlling on / off of voice input on the own apparatus side.   The echo prevention function transmits and receives predetermined command information based on a signal related to the intention to transmit input by manual operation of the user interface or a signal related to the utterance state automatically detected by the silence detection unit, and 4. The acoustic echo prevention apparatus according to claim 3, wherein the voice input is on / off controlled based on command information. It can communicate with other acoustic echo prevention devices via the network,
Equipped with an echo prevention function for on / off control of voice input on the other acoustic echo prevention device side via the network when the own device is not outputting voice data at the time of voice input of the own device. A characteristic acoustic echo prevention device.   The echo prevention function refers to a predetermined command information based on a signal relating to a speech transmission input by manual operation of a user interface or a signal relating to an utterance state automatically detected by a silence detection unit, to other acoustic echoes. The acoustic echo prevention apparatus according to claim 5, wherein the audio input on the other acoustic echo prevention apparatus side is on / off controlled by transmitting to the prevention apparatus. It is possible to communicate with multiple acoustic echo prevention devices via a network,
When an audio packet is received from one acoustic echo prevention device side, the audio packet is analyzed, and predetermined control information based on the result of the analysis is sent out on the other acoustic echo prevention device side. A centralized management apparatus that performs on / off control of voice input on another acoustic echo prevention apparatus side.   An acoustic echo prevention method by a centralized management device capable of communicating with a plurality of acoustic echo prevention devices via a network, and when the centralized management device receives a voice packet from one acoustic echo prevention device side, the voice Analyzing the packet, and sending out predetermined control information based on the result of the analysis on the other acoustic echo prevention device side, to turn on / off the voice input on the other acoustic echo prevention device side A characteristic acoustic echo prevention method. An acoustic echo prevention program by an acoustic echo prevention device capable of communicating with other acoustic echo prevention devices via a network,
The acoustic echo prevention device executes an echo prevention function for controlling on / off of at least one of the voice input on the own device side and the voice input on the other acoustic echo prevention device side via the network at the time of transmission. An acoustic echo prevention program characterized by   The echo prevention function is an on / off control of the voice input based on a signal related to the intention to transmit input by manual operation of the user interface or a signal related to the utterance state automatically detected by the silence detection unit. The acoustic echo prevention program according to claim 9, wherein: An acoustic echo prevention program by an acoustic echo prevention device capable of communicating with other acoustic echo prevention devices via a network,
The acoustic echo prevention device controls on / off the voice input on the other acoustic echo prevention device side via the network at the time of voice input on the own device side, or the other sound on the voice input on the other acoustic echo prevention device side. An acoustic echo prevention program for executing an echo prevention function for on / off control of voice input on the device side according to control by the echo prevention device.   The echo prevention function transmits and receives predetermined command information based on a signal related to the intention to transmit input by manual operation of the user interface or a signal related to the utterance state automatically detected by the silence detection unit, and The acoustic echo prevention program according to claim 11, wherein the voice input is on / off controlled based on command information. An acoustic echo prevention program by an acoustic echo prevention device capable of communicating with other acoustic echo prevention devices via a network,
If the sound echo prevention apparatus is not outputting sound data when the sound input of the apparatus itself is being performed, an echo for on / off controlling the sound input on the other acoustic echo prevention apparatus via the network An acoustic echo prevention program characterized by executing a prevention function.   The echo prevention function refers to transmitting predetermined command information based on a signal related to the intention to transmit input by manual operation of the user interface or a signal related to the utterance state automatically detected by the silence detection unit. The acoustic echo prevention program according to claim 13, wherein the voice input is on / off controlled based on the command information.

Images