JP4919077B2 - Voice communication terminal and voice communication system - Google Patents

Description

  The present invention relates to a voice communication terminal and a voice communication system that perform voice communication via a transmission line having a plurality of channels.

Conventionally, various voice communication terminals for generating voice signals for each speaker and performing voice communication have been devised (see Patent Document 1). The conference call device of Patent Document 1 collects sound for each sound collection direction, that is, for each speaker, generates an audio signal, stores the audio signal in each channel of the transmission line, and outputs it. At this time, when the number of channels on the transmission line is larger than the number of speakers, voice communication can be performed using a different channel for each speaker, so that a voice signal can be distinguished for each speaker.
Japanese Unexamined Patent Publication No. Sho 63-31255

  However, if the number of channels on the transmission line is less than the number of speakers, the conference call device synthesizes the voice signals of the speakers at a predetermined ratio and mixes them down to a multi-channel signal, and then converts the multi-channel signal to the transmission line. Output. At this time, since all voice signals are synthesized with the same priority, the voice signal of a specific speaker cannot be distinguished from other voice signals.

  Therefore, an object of the present invention is to provide a voice communication terminal and a voice communication system that perform voice communication by distinguishing a voice signal of a specific speaker from other voice signals using a limited number of channels.

  The voice communication terminal according to the present invention synthesizes sound collecting means for collecting sound from the surroundings of its own device, generating a sound signal, a plurality of dedicated channels for transmitting specific sound signals in association with each other, and other sound signals. Communication control means for performing voice communication via a transmission line including a shared channel for transmission, and the communication control means is configured to transmit the voice if a dedicated channel is assigned in accordance with a set channel assignment. The signal is stored in a dedicated channel of the transmission line, and if a shared channel is assigned, the presence or absence of an audio signal already stored in the shared channel is confirmed, and if there is another audio signal, the other audio signal And the collected audio signal are stored in a shared channel and output.

  In this configuration, the voice communication terminal performs voice communication via a transmission line including a plurality of dedicated channels that respectively transmit specific voice signals and a shared channel that combines and transmits other voice signals. The voice communication terminal stores the collected voice signal in a dedicated channel of the transmission line if the voice signal is assigned to a dedicated channel, and shares the transmission line if the collected voice signal is assigned to a shared channel. Store in channel and output. As a result, the voice communication terminal can transmit a specific voice signal in distinction from other voice signals, and can also reliably transmit other voice signals, even if transmission lines with a limited number of channels are used.

  In the audio communication terminal of the present invention, the communication control means attenuates the signal level of the audio signal by a predetermined level if the signal level of the audio signal to be stored in the shared channel is equal to or higher than a preset clip prevention threshold. It is characterized by making it.

  In this configuration, the audio communication terminal attenuates the signal level of the audio signal by a predetermined level when the signal level of the audio signal to be stored in the shared channel is equal to or higher than the predetermined clip prevention threshold. As a result, it is possible to prevent clipping (sound cracking) of the audio signal stored in the shared channel, so that a large number of audio signals can be synthesized and stored in the shared channel.

  Furthermore, the voice communication system of the present invention is a voice communication system in which voice communication terminals are connected by a transmission line capable of communicating using a plurality of channels, and one of the plurality of voice communication terminals is set as a master, The communication control means of the plurality of voice communication terminals makes a channel acquisition request to the master voice communication terminal when the sound pickup means generates a voice signal, and outputs output channel designation information of the voice signal from the master voice communication terminal. Acquiring and storing the audio signal in a designated channel.

  In this configuration, the voice communication system includes the plurality of voice communication terminals and is connected using the transmission line. The plurality of voice communication terminals make an acquisition request for the storage destination channel of the collected voice signal to the master voice communication terminal. When the channel of the transmission line for storing the collected audio signal is designated by the master audio communication terminal, the audio communication terminal stores the collected audio signal in the designated channel.

  According to the present invention, the voice communication terminal assigns a specific voice signal to each of the plurality of dedicated channels and assigns another voice signal to the shared channel. As a result, even if transmission lines with a limited number of channels are used, specific audio signals can be transmitted separately from other audio signals. As a result, for example, if these audio signal groups are emitted, the main utterances of the conference can be clearly heard and at the same time the utterances of the surrounding conference participants can be grasped.

  A voice communication terminal 1 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory diagram of voice communication using a voice communication terminal. FIG. 2 is an explanatory diagram relating to an audio block for storing an audio signal. FIG. 3 is a block diagram showing a functional configuration of the voice communication terminal. FIG. 3A shows a functional configuration of the master voice communication terminal. FIG. 3B shows a functional configuration of the slave voice communication terminal.

  As shown in FIG. 1, the voice communication system includes a plurality of voice communication terminals 1a to 1e, and a user 2 (2a to 2j) is seated around the voice communication system. Each voice communication terminal 1 (1a to 1e) is connected via a communication cable, and is set to a master voice communication terminal 1a and slave voice communication terminals 1b to 1e. Each voice communication terminal 1 performs voice communication with the other voice communication terminals 1 by storing the collected voice signals in the voice signal blocks 3 (3a to 3e) each transmitting on the transmission line. Each of the audio signal blocks 3 includes three dedicated channels CH0 to CH2 and one shared channel CH3. The dedicated channels CH0 to CH2 store specific audio signals designated by the master audio communication terminal 1a. Other audio signals are synthesized and stored in the shared channel CH3. When the audio signal is stored in the shared channel CH3, if the signal level of the synthesized audio signal is equal to or higher than the clipping prevention threshold, the synthesized audio signal is stored after being attenuated by 6 dB.

  As described above, since the specific audio signal is stored in the dedicated channels CH0 to CH2 and the other audio signals are stored in the shared channel CH3, the specific audio signal can be reliably transmitted. When a conference is performed using, the speech of the main speaker of the conference can be reliably transmitted. In addition, since the voices of other participants can also be transmitted, the main voices of the conference can be clearly heard by playing (sounding) this group of audio signals, and the voices of other conference participants can be heard at the same time. You can also grasp about.

  First, the audio signal block 3 transmitted and received between the audio communication terminals 1 will be described with reference to FIG. The audio signal block 3 includes a data unit 32 that stores an audio signal and a header unit 31 that registers various information of the audio signal stored in the data unit 32.

  The data unit 32 includes three dedicated channels CH0 to CH2 and one shared channel CH3. In the dedicated channels CH0 to CH2, specific audio signals associated in advance with the dedicated channels CH0 to CH2 are stored. The shared channel CH3 stores other audio signals that are not associated with the dedicated channels CH0 to CH2.

  In the header portion 31, channel information, a volume counter, and the like are registered. In the channel information, sound collection source information for specifying the audio signals stored in the channels CH0 to CH3 is registered. This sound collection source information is composed of the identification number of the voice communication terminal 1 that picks up the voice signal and the sound collection directivity information of the voice signal. The initial value of the channel information is null. Further, when a plurality of audio signals are synthesized and stored in the shared channel CH3, sound collection source information for specifying the last synthesized audio signal is registered. The volume counter is a counter that stores the number of times that the audio signal stored in the shared channel CH3 has been attenuated by 6 dB. The initial value of the volume counter is 0, and the counter value is incremented by 1 every time 6 dB is attenuated. That is, by referring to the volume counter, the attenuation amount of the signal level of the audio signal stored in the shared channel CH3 can be calculated.

  Next, the functional configuration of the voice communication terminal 1 will be described. The voice communication terminal 1 includes an input / output connector 11, a communication control unit 12, a sound emission control unit 13, a speaker array 14, a microphone array 15, an operation unit 16, a control unit 17, a sound collection control unit 18, and an echo canceller 19. Is done.

  The input / output connector 11 is a connection terminal connected to another voice communication terminal via a communication cable. When connecting to an external network, a LAN port may be provided, and these connection terminals may be installed as appropriate according to the system specifications.

  The communication control unit 12 includes an adding unit 121 and a clip monitoring unit 122. The communication control unit 12 controls the audio signal block 3 and various signals transmitted / received via the input / output connector 11.

  The communication control unit 12 stores the audio signal input from the echo canceller 19 in the corresponding channel of the audio signal block 3 based on the channel specifying signal (cs) that specifies the storage destination channel of the audio signal. When storing the audio signal in the shared channel CH3, the communication control unit 12 synthesizes the audio signal already stored in the shared channel CH3 and the collected sound signal of its own device in the adding unit 121. Further, the clip monitoring unit 122 monitors whether or not the signal level of the synthesized audio signal is equal to or higher than the clipping prevention threshold. If the signal level is equal to or higher than the clipping prevention threshold, the clip monitoring unit 122 attenuates the synthesized audio signal by 6 dB. The details of the processing when the audio signal is stored in the audio signal block 3 will be described later.

  The sound emission control unit 13 responds to each speaker of the speaker array 14 based on an instruction from the control unit 17 for each audio signal of the audio signal block 3 input from the communication control unit 12 via the echo canceller 19. The sound output directivity control, D / A conversion, amplification, and the like are performed, and the generated audio signal is output to the speaker array 14.

  The speaker array 14 includes a plurality of omnidirectional speakers, and emits a sound signal input from the sound emission control unit 13. The speaker array 14 may be composed of directional speakers.

  The microphone array 15 includes a plurality of microphones. The microphone array 15 electrically converts the sound collected by the microphone array 15 to generate a sound signal, and outputs the sound signal to the sound collection control unit 18.

  The operation unit 16 receives an operation input from the user 2 and outputs the operation input content to the control unit 17. For example, the operation input content includes setting of a master or slave, setting of a signal level of an output audio signal, setting of a channel designation method, and the like.

  The control unit 17 controls each functional unit based on the operation input content input from the operation unit 16. When the sound collection control unit 18 generates an audio signal, the control unit 17 transmits distribution information (di) for requesting acquisition of a channel to the master audio communication terminal 1a, and receives a channel designation signal from the master audio communication terminal 1a. (Cs) is acquired. In addition, the control part 17 of the master audio | voice communication terminal 1a will produce | generate a channel designation | designated signal (cs) based on the channel designation | designated method input from the operation part 16, if distribution information (di) is acquired.

  The distribution information (di) includes the identification number of the voice communication terminal and the sound collection directivity information, and is used for identifying the voice signal from which the channel is to be acquired. The channel designation signal (cs) includes the storage channel of the audio signal.

  A prefetch method is used as a channel designation method. This prefetching method is a method of assigning dedicated channels CH0 to CH2 in the order of channel acquisition requests. That is, when the control unit 17 of the master voice communication terminal 1a acquires the distribution information (di), first, the dedicated channels CH0 to CH2 are uniquely assigned to the audio signal registered in the distribution information (di). At this time, if another audio signal has already been assigned to the dedicated channels CH0 to CH2, the control unit 17 of the master audio communication terminal 1a uses the shared channel CH3 for the audio signal registered in the distribution information (di). Assign.

  The dedicated channels CH0 to CH2 may always be assigned the same audio signal during audio communication, or the audio signals assigned to the dedicated channels CH0 to CH2 may be released by an operation input from the operation unit 16. Good. When the dedicated channels CH0 to CH2 are released, new audio signals are assigned to the dedicated channels CH0 to CH2 based on the channel designation method.

  When a sound signal is input from the microphone array 15, the sound collection control unit 18 performs amplification, A / D conversion, and sound collection directivity control on the sound signal, and the generated sound signal is echo canceller 19. And the sound collection directivity information of the audio signal is generated and output to the control unit 17.

  The echo canceller 19 removes an echo from the audio signal input from the sound collection control unit 18 and outputs it to the communication control unit 12.

  Next, the flow of processing when the audio signal is collected by the slave audio communication terminals 1b to 1e and then stored in the corresponding channel of the audio signal block 3 will be described with reference to FIG. . FIG. 4 is a flowchart showing a processing flow when an audio signal is stored in an audio signal block. In the following, the case where the slave voice communication terminal 1b picks up a voice signal will be described as an example.

  As shown in FIG. 4, when the slave voice communication terminal 1b picks up the voice signal (S101), the slave voice communication terminal 1b checks whether or not channels CH0 to CH3 are assigned to the voice signal (S102). If it is assigned (S102: Yes), the process proceeds to step S105.

  When the channels CH0 to CH3 are not assigned to the audio signal (S102: No), the slave audio communication terminal 1b generates the distribution information (di) and requests the distribution information (di) to make a channel acquisition request. di) is transmitted to the master voice communication terminal 1a (S103).

  When receiving the distribution information (di), the master audio communication terminal 1a determines a channel for storing the audio signal registered in the distribution information (di) based on the above-described channel designating method (S121). A channel designation signal (cs) designating the signal storage channel is transmitted to the voice communication terminal 1b registered in the distribution information (di) (S122).

  The slave voice communication terminal 1b receives the channel designation signal (cs) (S104), and proceeds to step S105.

  In step S105, the slave voice communication terminal 1b checks whether or not the channels assigned to the voice signals are the dedicated channels CH0 to CH2. When the channel is the dedicated channel CH0 to CH2 (S105: Yes), the audio signal is stored in the corresponding dedicated channel of the audio signal block 3 (S111).

  When the channel assigned to the audio signal is not the dedicated channel CH0 to CH2, that is, when the shared channel CH3 is assigned (S105: No), the slave audio communication terminal 1b stores the audio signal in the shared channel CH3. It is checked whether or not (S106). When the audio signal is not stored (S106: No), the audio signal is stored in the common channel CH3 of the audio signal block 3 (S111).

  When another audio signal is stored in the shared channel CH3 (S106: Yes), the slave audio communication terminal 1b acquires the audio signal stored in the shared channel CH3 (S107). The slave audio communication terminal 1b synthesizes the collected audio signal and the audio signal acquired from the shared channel CH3 (S108), and whether the signal level of the synthesized audio signal is equal to or higher than a predetermined clip prevention threshold value. (S109). If it is equal to or greater than the clipping prevention threshold (when clipping) (S109: Yes), the synthesized audio signal is attenuated by 6 dB (S110), and it is checked whether or not clipping occurs again (S109). If it is less than the clipping prevention threshold (when not clipping) (S109: No), the synthesized audio signal is stored in the shared channel CH3 of the audio signal block 3 (S111). The storage of the collected audio signal in the audio signal block 3 is thus completed. At this time, as described above, when the synthesized audio signal is clipped, it is possible to prevent the synthesized audio signal from being clipped by attenuating the signal level of the synthesized audio signal by 6 dB.

  When the master voice communication terminal 1a picks up the voice signal, the output destination channel of the voice signal is determined in the own apparatus based on the channel designation method described above, and the voice signal is sent to the output destination channel. Is stored.

  Next, a specific example of sound collection and transmission processing using the above-described voice communication system will be described with reference to FIG. FIG. 5 is an explanatory diagram of sound collection and transmission processing using the voice communication system. 5A shows the time 0, FIG. 5B shows the time 1, FIG. 5C shows the time 2, and FIG. 5D shows the time 3.

  As shown in FIG. 5A, when the user 2i speaks at time 0, the voice communication terminal 1e picks up the voice and generates a voice signal, and also delivers the delivery information (di) of the voice signal. Generate. The voice communication terminal 1e sends distribution information (di) to the master voice communication terminal 1a to make a channel acquisition request. When receiving the distribution information (di), the master voice communication terminal 1a allocates the dedicated channel CH0 to the voice signal indicated by the distribution information (di) based on the channel designation method described above. The master voice communication terminal 1a generates a channel designation signal (cs) that designates the dedicated channel CH0, and transmits the channel designation signal (cs) to the voice communication terminal 1e that is the transmission source of the distribution information (di). When receiving the channel designation signal (cs), the voice communication terminal 1e stores and outputs the generated voice signal in the dedicated channel CH0 designated by the channel designation signal (cs).

  As shown in FIG. 5B, when the users 2h and 2g speak at time 1, the voice communication terminal 1d picks up the respective voices to generate each voice signal and distributes each voice signal. Information (di) is generated. The voice communication terminal 1d transmits the distribution information (di) to the master voice communication terminal 1a to make a channel acquisition request. When receiving the distribution information (di), the master voice communication terminal 1a assigns dedicated channels CH1 and CH2 to the audio signals indicated by the distribution information (di) based on the channel designation method described above. The master voice communication terminal 1a generates channel designation signals (cs) for designating the dedicated channels CH1 and 2, and transmits the channel designation signals (cs) to the voice communication terminal 1d that is the transmission source of the distribution information (di). Upon receiving these channel designation signals (cs), the voice communication terminal 1d stores and outputs the generated voice signals in the dedicated channels CH1 and 2 designated by the channel designation signal (cs).

  As shown in FIG. 5C, when the user 2e speaks at time 2, the voice communication terminal 1c picks up the voice and generates a voice signal, and also delivers the delivery information (di) of the voice signal. Generate. The voice communication terminal 1c sends distribution information (di) to the master voice communication terminal 1a to make a channel acquisition request. When receiving the distribution information (di), the master voice communication terminal 1a has no vacancy in the dedicated channels CH0 to CH2 based on the above-described channel designation method. The shared channel CH3 is assigned. The master voice communication terminal 1a generates a channel designation signal (cs) that designates the shared channel CH3, and transmits the channel designation signal (cs) to the voice communication terminal 1c that is the transmission source of the distribution information (di). When the voice communication terminal 1c receives the channel designation signal (cs), no voice signal is stored in the shared channel CH3 designated by the channel designation signal (cs), so the generated voice signal is stored in the shared channel CH3. Output.

  As shown in FIG. 5D, when the user 2d speaks at time 3, the voice communication terminal 1b picks up the voice and generates a voice signal, and also delivers the delivery information (di) of the voice signal. Generate. The voice communication terminal 1b transmits distribution information (di) to the master voice communication terminal 1a to make a channel acquisition request. When the master voice communication terminal 1a receives the distribution information (di), the dedicated channels CH0 to CH2 have no vacancy based on the channel designation method. Assign CH3. The master voice communication terminal 1a generates a channel designation signal (cs) that designates the shared channel CH3 and transmits it to the voice communication terminal 1b that is the transmission source of the distribution information (di). When receiving the channel designation signal (cs), the voice communication terminal 1b acquires the voice signal from the shared channel CH3 because the voice signal is stored in the shared channel CH3 designated by the channel designation signal (cs). The voice communication terminal 1b synthesizes the generated voice signal and the acquired voice signal, and checks whether the signal level of the synthesized voice signal exceeds the clip prevention threshold. When the clip prevention threshold is exceeded, the signal level is attenuated by 6 dB, stored in the shared channel CH3, and output.

  As described above, by performing sound collection and transmission processing, it is possible to transmit five audio signals having more than four channels on the transmission line. In addition, since the audio signals of the users 2g to 2i are stored in the dedicated channels CH0 to CH3, the audio signals of the users 2d and 2e are synthesized, stored in the shared channel CH3, and then output, It is possible to transmit clearly other words and messages of other users 2d and 2e.

  Next, a voice communication method between remote locations using the voice communication system described above will be described with reference to FIG. FIG. 6 is an explanatory diagram of voice communication between other bases.

  As shown in FIG. 6, a voice communication system composed of voice communication terminals 1 (1a to 1e) is installed at the site 4a, and a voice communication terminal 1 '(1a' to 1e ') is installed at the site 4b. A configured voice communication system is installed. A master voice communication terminal 1a and a master voice communication terminal 1a 'installed between remote locations are connected via a network.

  The master voice communication terminal 1a ′ installed at the base 4b is a master of the voice signal block 3b in which voice signals based on the sound collected by the voice communication terminals 1a ′ to 1e ′ are stored, at the remote base 4a. To the voice communication terminal 1a via the network. The master voice communication terminal 1a ′ installed at the base 4b receives the voice signal block 3a from the master voice communication terminal 1a installed at the remote base 4a via the network, and receives the voice signal block 3a. 3a is transmitted to the slave voice communication terminals 1b 'to 1e'.

  Upon receiving the audio signal block 3a, each of the audio communication terminals 1a ′ to 1e ′ emits the audio signals stored in the dedicated channels CH0 to CH2 with directivity from different predetermined directions, and sends them to the shared channel CH3. The stored audio signal is emitted omnidirectionally. As a result, since the audio signals stored in the dedicated channels CH0 to CH2 are emitted with different sound emission directivities, the audio signals of the dedicated channels CH0 to CH2 are more easily identified from other audio signals. be able to. Further, by emitting sound signals stored in the shared channel CH3 in a non-directional manner, other sound signals other than the dedicated channels CH0 to CH2 can be heard.

  In this embodiment, the prefetch method is used as the channel designation method, but a priority order method or a mixing method may be used.

  The priority order method is a method in which dedicated channels CH0 to CH2 are set in advance for a predetermined audio signal and the dedicated channels CH0 to CH2 are assigned to the predetermined audio signal. The shared channel CH3 is assigned to the audio signal to which the dedicated channels CH0 to CH2 are not assigned. For example, in a product review, dedicated channels CH0 to CH2 are assigned to the progressors, presenters, and reviewers by the priority order method. As a result, it is possible to preferentially and reliably transmit the remarks of the progressors, presenters, and reviewers who are the main speakers of the product review session. In addition, since the voices of other participants are collected and stored in the shared channel CH3, the voices of other participants can also be transmitted.

  The mixing method is a method in which the channel designation method and the priority order method are mixed. For some channels of the dedicated channels CH0 to CH2, audio signals are assigned by the priority order method, and the audio signal is assigned by the priority order method. This is a method of assigning an audio signal to the remaining channels to which no signal is assigned by a prefetch method. For example, in the conference, dedicated channels CH0 and CH1 are assigned to the chairperson and the presenter by the priority order method, and the dedicated channel CH2 is assigned to the interrogator by the preemptive method. This makes it possible to preferentially and reliably transmit the speech of the chairperson, the presenter who is the main speaker of the conference, and the questioner who cannot be specified at the start of the conference. In addition, since the voices of other participants are collected and stored in the shared channel CH3, the voices of other participants can also be transmitted.

  In the present embodiment, the release of the dedicated channels CH0 to CH2 is performed by an operation input from the operation unit 16, but it is detected that the audio signal assigned to the dedicated channels CH0 to CH2 is no longer stored. The allocation may be released after a certain time has elapsed. Alternatively, the allocation may be released after a predetermined time has elapsed since the audio signals were allocated to the dedicated channels CH0 to CH2.

  In the present embodiment, once a channel is assigned, the audio communication terminal 1 stores the audio signal in the stored channel in the subsequent audio signal block 3, and stores the audio signal in a new different direction. When it makes a sound, it requests the master voice communication terminal 1a to newly acquire the channel designation information (cs). However, only the master audio communication terminal 1a stores the channel assigned to the audio signal, and the audio communication terminal 1 collects the audio signal and stores it in the audio signal block 3 each time it stores the audio signal. ) May be requested to the master voice communication terminal 1a.

  Further, in the present embodiment, the audio signal stored in the audio signal block 3 by the audio communication terminal 1 is emitted by the remote audio communication system, but is controlled by the master audio communication terminal 1a and within the same site. The sound communication terminals 1a to 1e may emit sound. That is, the collected audio signal may be amplified and emitted. Further, the audio signal block 3 may be stored in a storage device under the control of the master audio communication terminal 1a.

  In addition, in the present embodiment, the audio signal block 3 is configured by three dedicated channels CH0 to CH2 and one shared channel CH3, but may be configured by a plurality of dedicated channels and shared channels. The number of each channel is not limited.

  In the present embodiment, every time an audio signal is stored in the shared channel CH3, the sound collection source information of the last collected audio signal is registered in the channel information of the shared channel CH3. However, since it is only necessary to know whether the audio signal is stored in the shared channel CH3 of the audio signal block 3, only when the audio signal is first stored in the shared channel CH3, the sound source information of the audio signal is stored in the channel of the shared channel CH3. Information may be registered.

It is explanatory drawing of the voice communication using a voice communication terminal. It is explanatory drawing regarding the audio | voice block which stores an audio | voice signal. It is a block diagram which shows the function structure of a voice communication terminal. It is a flowchart which shows the flow of a process at the time of storing an audio | voice signal in an audio | voice signal block. It is explanatory drawing of the sound collection and transmission process which used the audio | voice communication system. It is explanatory drawing of the voice communication between other bases.

Explanation of symbols

1-voice communication terminal, 2-user, 3-voice signal block, 4-base, 11-input / output connector, 12-communication control section, 13-sound emission control section, 14-speaker array, 15-microphone array, 16 Operation unit, 17-control unit, 18-sound pickup control unit, 19-echo canceller, 31-header unit, 32-data unit, 121-adder unit, 122-clip monitoring unit, CH0 to CH2-dedicated channel, CH3 -Shared channel

Claims (3)

Sound collecting means for collecting sound from the surroundings of the device and generating an audio signal;
A communication control means for performing voice communication via a transmission line including a plurality of dedicated channels for transmitting specific audio signals in association with each other and a shared channel for combining and transmitting other audio signals;
The communication control means stores the audio signal in the dedicated channel of the transmission line if a dedicated channel is allocated according to the set channel allocation, and is already stored in the shared channel if a shared channel is allocated. A voice communication terminal that checks the presence or absence of a voice signal and, if there is another voice signal, synthesizes the other voice signal and the collected voice signal, stores them in a shared channel, and outputs them.   The audio communication terminal according to claim 1, wherein the communication control means attenuates the signal level of the audio signal by a predetermined level if the signal level of the audio signal to be stored in the shared channel is equal to or higher than a preset clip prevention threshold. . A voice communication system in which a plurality of voice communication terminals according to claim 1 or claim 2 are connected by a transmission line capable of communicating using a plurality of channels according to claim 1 or claim 2,
One of the plurality of voice communication terminals is set as a master,
The communication control means of the plurality of voice communication terminals makes a channel acquisition request to the master voice communication terminal when the sound pickup means generates a voice signal, and outputs output channel designation information of the voice signal from the master voice communication terminal. An audio communication system that acquires and stores the audio signal in a designated channel.

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