JP2008092331A - Voice conference apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voice conference apparatus, in simple configuration, in which all conference participants can listen to voices of each of speakers even when a voice conference is held in a wide space. <P>SOLUTION: Voice signals SsA collected by a voice conference apparatus 1A are amplified 1.2 times and emitted from a voice conference apparatus 1B. Furthermore, voice signals (SsA×1.2) emitted from the voice conference apparatus 1B are amplified 1.2 times at the voice conference apparatus 1B and emitted from a voice conference apparatus 1C. Moreover, voice signals (SsA×1.2^2) emitted from the voice conference apparatus 1C are amplified 1.2 times at the voice conference apparatus 1C and emitted from a voice conference apparatus 1D. Direct voices of a conferee 200A become hard to hear as being away from the conferee 200A however since the volume of emitted voices from the voice conference apparatus becomes high, the participant can listen to the voices of approximately equal volume at any sitting position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an audio conference system, and more particularly to an audio conference device in which a plurality of audio conference devices are arranged in a wide space.

In recent years, an audio conference apparatus has been proposed that is used when a conference is performed in a conference room or a conference hall (see, for example, Patent Document 1). The apparatus of Patent Document 1 adjusts the sound pressure level and the amount of delay using two speakers, and performs acoustic correction so that sound can be heard from a distance from the speaker position.
Japanese Patent Laid-Open No. 10-233554

  However, with the apparatus described in Patent Document 1, it was not possible to carry out a conversation with a plurality (three or more persons) in the same space. A conference participant who is far from the speaker must listen to the sound produced by the speaker, but cannot hear the content of the speech if he / she is away from the speaker. If a speaker is installed in each conference participant, the system becomes large-scale, and setting of the sound pressure level and the delay amount becomes complicated.

  An object of the present invention is to provide an audio conferencing apparatus with a simple configuration that enables all the conference participants to listen to the utterance sound of each speaker even when performing an audio conference in a vast space. To do.

  An audio conference apparatus according to the present invention includes a plurality of audio signal input units, a plurality of audio signal output units, a sound output unit that emits an input audio signal, and collects audio to generate a collected audio signal An audio signal input from the plurality of audio signal input units, an input audio signal addition unit that adds the audio signals input from the plurality of audio signal input units and inputs the input to the sound output unit, and an audio signal input from the plurality of audio signal input units A sound signal superimposing unit that superimposes the collected sound signal on each of the sound signal and outputs the superimposed signal to the plurality of sound signal output units, and a sound signal input from the plurality of sound signal input units, or the plurality of sound signals And a plurality of audio signal amplifying units for amplifying each of the audio signals output to the signal output unit with a predetermined amplification factor.

  In this configuration, the audio signal collected by the own device is superimposed on each of the plurality of audio signals input from the other device and transmitted to the other device. In addition, each of a plurality of audio signals input from another device or the audio signal after being superimposed is amplified and transmitted to the other device. What is necessary is just to set an amplification factor suitably according to an installation position (distance with another audio conference apparatus). As a result, the sound picked up by the own device is emitted by all of the other devices, and the volume level increases as the device is farther from the own device, so that all conference participants can listen at the same volume. it can.

  The present invention further includes a level adjusting unit that attenuates the level of the audio signal to the predetermined threshold when the audio signals input from the plurality of audio signal input units have a signal level equal to or higher than a predetermined threshold. Features.

  In this configuration, a limiter is provided that attenuates to a threshold value when an audio signal input from another device has a level equal to or higher than a predetermined threshold value. Even when a large number of audio conference apparatuses are connected and an audio signal of a predetermined level or higher is input, the volume does not become too high. Moreover, an excessive input can be prevented and a speaker can be protected.

  The present invention further includes an adaptive filter that inputs an audio signal to be input to the sound emitting unit and outputs a pseudo signal of a regression audio signal from the sound emitting unit to the sound collecting unit; and An echo canceller comprising a post processor for subtracting from an audio signal is provided.

  In this configuration, the echo component is suppressed by the adaptive filter that estimates the transfer function of the acoustic transfer system from the speaker to the microphone. It is possible to suppress the acoustic coupling between the speaker and the microphone in the same audio conference apparatus and to emit a sound with a larger volume.

  The present invention further detects a frequency characteristic of an audio signal input to the sound emitting unit, and performs an attenuation process for attenuating the level of the frequency when occurrence of howling and its frequency are detected based on the frequency characteristic. It has a howling canceller.

  In this configuration, howling is generated and its frequency is detected by detecting the frequency characteristics of the audio signal input to the speaker. Attenuates the detected frequency and suppresses howling. By suppressing the howling, it is possible to suppress the acoustic coupling between the audio conference apparatuses and to emit sound at a higher volume.

  The present invention further includes a delay unit that adds a predetermined delay amount to the audio signals output to the plurality of audio signal output units.

  In this configuration, a delay circuit is provided that adds a delay amount to the audio signal output to the other device. When the voice signal transmitted between the devices arrives earlier than the voice generated by the speaker (direct sound transmitted through the space), the arrival timing is adjusted by the delay circuit.

  According to the present invention, even when an audio conference is performed in a vast space, the volume of the emitted sound increases as the distance from the speaker increases. You can listen. As a result, the emitted sound reaches the listener at approximately the same time as the direct sound, enabling a more natural conversation.

An audio conference system according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of the audio conference system according to the present embodiment, and FIG. 2 is a block diagram illustrating a configuration of the audio conference apparatus 1 (1A to 1D). FIG. 3 is a configuration diagram showing audio communication wiring of the audio conference system according to the present embodiment.
Although the present embodiment shows a case where there are four audio conference apparatuses, the number of installations may be set as appropriate based on the size of the conference room, the number of participants, etc., without being limited to this number.

  As shown in FIG. 1, the audio conference system according to the present embodiment includes a plurality of audio conference apparatuses 1 </ b> A to 1 </ b> D arranged in a conference room 100 having a large space such as a large conference room. The plurality of audio conference apparatuses 1A to 1D have the same hardware configuration and software configuration. The audio conference apparatuses 1A to 1D are arranged on the desk 101 in a straight line.

  Each of the audio conference apparatuses 1A to 1D has one conference person 200A to 200D, and performs an audio conference using the corresponding audio conference apparatuses 1A to 1D. In the description of this embodiment, an example in which one conference person 200 is present in one audio conference apparatus 1 is shown. However, a plurality of conference persons are simultaneously present in one audio conference apparatus. May be.

As shown in FIG. 2, the audio conference apparatus 1 includes a microphone 21, a mixing unit 11, an amplifier (AMP) 19, and a speaker 22.
In the figure, a front-end amplifier mounted on a microphone, an AD converter that converts an analog audio signal collected by the microphone into a digital audio signal, and a DA that converts a digital audio signal supplied to a speaker into an analog audio signal. The description of the converter and the amplifier that amplifies the analog audio signal is omitted, and all audio signals transmitted in and between the devices are digital audio signals unless otherwise specified.

The microphone 21 collects sound around the audio conference device 1 and outputs an audio signal (acquired audio signal) to the mixing unit 11.
The mixing unit 11 includes mixers 111L and 111R and an adder 502. The collected sound signals input from the microphone 21 are input to the mixers 111L and R, respectively. In addition, audio signals input from the outside are input to the mixers 111L and 111R, respectively. Here, the mixer 111L mixes the audio signal input from the audio input terminal R (In R) and the collected audio signal and outputs the mixed audio signal to the amplifier 19L. The amplifier 19L amplifies the audio signal input from the mixer 111L with a predetermined amplification factor (for example, 1.2 times) and outputs the amplified audio signal to the audio output terminal L (Out L). The mixer 111R mixes the audio signal input from the audio input terminal L (IN L) and the collected audio signal and outputs the mixed signal to the amplifier 19R. The amplifier 19R amplifies the audio signal input from the mixer 111R with a predetermined amplification factor (eg, 1.2 times) and outputs the amplified audio signal to the audio output terminal R (Out R). The adder 502 adds the audio signal input from the audio input terminal R and the audio signal input from the audio input terminal L, and inputs this to the speaker 22. As a result, the audio signal input from the audio input terminal L and the audio signal input from the audio input terminal R are added and emitted. Furthermore, the audio signal input from the audio input terminal L is output from the audio output terminal R with the collected audio signal collected by the apparatus superimposed thereon. The audio signal input from the audio input terminal R is output from the audio output terminal L with the collected audio signal collected by the apparatus superimposed thereon.

  In the above example, the amplifier 19 is connected between the mixer 11 and the audio output terminal. However, the amplifier 19 is connected between the audio input terminal and the mixer 11 to amplify the audio signal on the input side. May be.

The voice conference apparatuses 1 (1A to 1D) as described above are connected to each other as shown in FIG. 3, so that the voice collected by each voice conference apparatus 1 can be sent to each voice conference without a central controller. Sound can be emitted from the device 1.
As shown in FIG. 3, the audio output terminal L (Out L) of the audio conference apparatus 1A is connected to the audio input terminal R (In R) of the audio conference apparatus 1B, and the audio output terminal R (Out L) of the audio conference apparatus 1B. R) is connected to the audio input terminal L (In L) of the audio conference apparatus 1A. Similarly, the audio output terminal L of the audio conference apparatus 1B is connected to the audio input terminal R of the audio conference apparatus 1C, and the audio output terminal R of the audio conference apparatus 1C is connected to the audio input terminal L of the audio conference apparatus 1B. The audio output terminal L of the audio conference apparatus 1C is connected to the audio input terminal R of the audio conference apparatus 1D, and the audio output terminal R of the audio conference apparatus 1D is connected to the audio input terminal L of the audio conference apparatus 1C. Has been.

  By adopting the connection mode as described above, for example, a collected voice signal collected by the audio conference apparatus 1A is input from the audio output terminal L to the audio input terminal R of the audio conference apparatus 1B, and the audio conference apparatus 1B Input to mixer 111L. Therefore, the collected audio signal collected by the audio conference apparatus 1A is input from the audio output terminal L of the audio conference apparatus 1B to the audio input terminal R of the audio conference apparatus 1C, and finally the audio of the audio conference apparatus 1D. It is also input to the input terminal R. On the contrary, the collected voice signal collected by the audio conference apparatus 1D is input from the audio output terminal R to the audio input terminal L of the audio conference apparatus 1C, and in turn, the audio conference terminal 1B and the audio input terminal of the audio conference apparatus 1A. L is input. In this way, the collected voice signal collected by each voice conference device 1 is input to all the other voice conference devices 1 connected thereto.

An example of a specific flow of an audio signal will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of sound collection and sound emission. A broken line indicates sound collection sound (voiced sound), and a solid line indicates sound emission sound.
In FIG. 5A, when a conference person 200A existing around the audio conference apparatus 1A utters, the audio signal SsA picked up by the microphone 21 of the audio conference apparatus 1A is amplified 1.2 times by the amplifier 19L. Output from the audio output terminal L. The audio signal (SsA × 1.2) output from the audio output terminal L of the audio conference apparatus 1A is input to the audio input terminal R of the audio conference apparatus 1B and emitted by the audio conference apparatus 1B.

  The audio signal (SsA × 1.2) input to the audio conference apparatus 1B is further amplified by 1.2 times by the amplifier 19L and output from the audio output terminal L. The audio signal (SsA × 1.2 ^ 2) output from the audio output terminal L of the audio conference apparatus 1B is input to the audio input terminal R of the audio conference apparatus 1C and emitted from the audio conference apparatus 1C. Similarly, the audio signal (SsA × 1.2 ^ 2) input to the audio conference apparatus 1C is further amplified by 1.2 times and output from the audio output terminal L. The audio signal (SsA × 1.2 ^ 3) output from the audio output terminal L of the audio conference apparatus 1C is input to the audio input terminal R of the audio conference apparatus 1D and emitted by the audio conference apparatus 1D.

  In FIG. 5B, when a conference person 200C existing around the audio conference apparatus 1C utters, the audio signal SsC collected by the microphone 21 of the audio conference apparatus 1C is multiplied by 1.2 by the amplifiers 19L and 19R. Amplified and output from the audio output terminal L and the audio output terminal R. The audio signal (SsC × 1.2) output from the audio output terminal L of the audio conference apparatus 1C is input to the audio input terminal R of the audio conference apparatus 1D and emitted by the audio conference apparatus 1D. Also, the audio signal (SsC × 1.2) output from the audio output terminal R of the audio conference apparatus 1C is input to the audio input terminal L of the audio conference apparatus 1B and is emitted from the audio conference apparatus 1B.

  The audio signal (SsC × 1.2) input to the audio conference apparatus 1B is further amplified by 1.2 times by the amplifier 19R and output from the audio output terminal R. The audio signal (SsC × 1.2 ^ 2) output from the audio output terminal R of the audio conference apparatus 1B is input to the audio input terminal L of the audio conference apparatus 1A and emitted by the audio conference apparatus 1A.

  As described above, the voice collected by each voice conference apparatus is amplified and emitted from another voice conference apparatus. As a result, the utterance sound of the conference participant 200A is provided to each conference participant at an optimum volume. As the distance from the conference 200A increases, it becomes difficult to hear the direct voice of the conference 200A. However, since the volume of the sound emitted from the audio conference device increases, the sound of the same volume can be obtained regardless of where the user is present. Can be heard. In the present embodiment, an example in which each conference apparatus amplifies the audio signal by 1.2 times has been described, but the amplification factor may be set as appropriate according to the installation position of each conference apparatus.

  Note that a measurement sound with a predetermined volume level may be emitted from any one of the audio conference apparatuses, and each audio conference apparatus may collect the measurement sound to obtain the amplification factor. For example, in FIG. 4A, the audio conference apparatus 1A emits a measurement sound from the speaker 22 and picks up the sound with the microphone 21 of the audio conference apparatus 1B. The audio conference apparatus 1B measures the level of the collected audio signal and compares it with a predetermined volume level of the measured sound. An attenuation factor of the level of the collected audio signal is obtained from a predetermined volume level of the measured sound, and the amplification factor of the amplifier is set so as to compensate for this attenuation. Similarly, the measurement sound emitted by the audio conference apparatus 1B is collected by the audio conference apparatus 1C, the amplification factor is set, and the measurement sound emitted by the audio conference apparatus 1C is collected by the audio conference apparatus 1D. Set the amplification factor.

Next, FIG. 5 is a block diagram showing the configuration of the audio conference apparatus according to the second embodiment of the present invention. In the figure, components common to the audio conference apparatus shown in FIG. 2 are denoted by the same reference numerals and description thereof is omitted.
As shown in FIG. 5, the audio conference apparatus 2 of this example includes a microphone 21, a mixing unit 11, an amplifier (AMP) 19, a speaker 22, and a limiter (LIMITER) 23.
The limiter 23 attenuates an audio signal having a level equal to or higher than a predetermined threshold, and keeps the level of the output audio signal below the threshold.
The limiters 23L and R receive audio signals from the audio input terminal L and the audio input terminal R, respectively. If the levels of the audio signals input from the audio input terminal L and the audio input terminal R are equal to or higher than the threshold, the limiters 23L and 23 attenuate the audio signal level to the threshold and output the result to the adder 502. The limiter 23L outputs the attenuated audio signal to the mixer 111R, and the mixer 23R outputs the attenuated audio signal to the mixer 111L. The mixer 111L mixes the sound signal input from the limiter 23R and the collected sound signal and outputs the mixed sound signal to the amplifier 19L. The amplifier 19L amplifies the audio signal input from the mixer 111L with a predetermined amplification factor (for example, 1.2 times) and outputs the amplified audio signal to the audio output terminal L (Out L). The mixer 111R mixes the audio signal input from the limiter 23L and the collected audio signal and outputs the mixed signal to the amplifier 19R. The amplifier 19R amplifies the audio signal input from the mixer 111R with a predetermined amplification factor (eg, 1.2 times) and outputs the amplified audio signal to the audio output terminal R (Out R). The adder 502 adds the audio signal input from the limiter 23L and the audio signal input from the limiter 23R, and inputs this to the speaker 22.

FIG. 6 is a diagram showing an example of voice collection and sound emission when four voice conference apparatuses 2 shown in FIG. 5 are connected. A broken line shows collected voice (voiced sound), and a solid line shows Indicates sound emission. The connection mode of the audio conference apparatuses 2A to 2D is the same as the connection mode of the audio conference apparatuses 1A to 1D shown in FIG.
In the same figure, when the conference person 200A existing around the audio conference apparatus 2A utters, the audio signal SsA picked up by the microphone 21 of the audio conference apparatus 2A is amplified 1.2 times by the amplifier 19L and is output to the audio output terminal. L is output. The audio signal (SsA × 1.2) output from the audio output terminal L of the audio conference apparatus 2A is input to the audio input terminal R of the audio conference apparatus 2B and emitted by the audio conference apparatus 2B.

  The audio signal (SsA × 1.2) input to the audio conference device 2B is further amplified by 1.2 times by the amplifier 19L and output from the audio output terminal L. The audio signal (SsA × 1.2 ^ 2) output from the audio output terminal L of the audio conference apparatus 2B is input to the audio input terminal R of the audio conference apparatus 2C and emitted from the audio conference apparatus 2C. Similarly, the audio signal (SsA × 1.2 ^ 2) input to the audio conference apparatus 2C is further amplified by 1.2 times and output from the audio output terminal L. The audio signal (SsA × 1.2 ^ 3) output from the audio output terminal L of the audio conference apparatus 2C is input to the audio input terminal R of the audio conference apparatus 2D. Here, since the audio signal (SsA × 1.2 ^ 3) input to the audio conference apparatus 2D exceeds the threshold value (Ss Limit) of the limiter 23, the audio signal is attenuated to the threshold value (Ss Limit) by the limiter 23. The sound is emitted from.

  Thus, by providing each audio conference device with a limiter, the volume does not become too high even if an audio signal of a predetermined level or higher is input. Moreover, an excessive input can be prevented and a speaker can be protected.

  Next, FIG. 7 is a block diagram illustrating a configuration of an audio conference apparatus according to the third embodiment. In the figure, components common to the audio conference apparatus shown in FIG.

As shown in FIG. 7, the audio conference apparatus 3 of this example includes a microphone 21, a mixing unit 11, an amplifier (AMP) 19, a speaker 22, a limiter (LIMITER) 23, an echo canceller 18, and a howling canceller 24. .
The echo canceller 18 includes an adaptive filter 181 and an adder 182. The adaptive filter 181 includes a digital filter such as an FIR filter. The adaptive filter 181 estimates the transfer function of the acoustic transfer system (sound propagation path from the speaker to the microphone), and calculates the filter coefficient of the FIR filter so as to simulate the estimated transfer function. The adaptive filter 181 generates a pseudo signal of a sneak component from the speaker to the microphone with the estimated filter coefficient. This pseudo signal is subtracted from the collected sound signal of the microphone 21 by the adder 182. Therefore, the output audio signal of the adder 182 is a signal obtained by removing the wraparound component from the audio signal collected by the microphone.

  The estimation of the transfer function and the calculation of the filter coefficient are performed using an adaptive algorithm based on the signal supplied to the speaker, using the residual signal that is the signal output from the adder 182. The adaptive algorithm is an algorithm that calculates filter coefficients so that the residual signal is as small as possible.

  As a result, a signal simulating the sneak signal of the acoustic transmission system is generated in the adaptive filter 181, and only the sneak signal can be efficiently attenuated by subtracting the pseudo signal from the collected sound signal in the adder 182. Thereby, the echo canceller 18 can prevent an echo generated by the sneak signal.

  The howling canceller 24 includes a notch filter that attenuates the level of a predetermined frequency or its peripheral band. The howling canceller 24 detects howling from the input audio signal and attenuates the level of a predetermined frequency or its surrounding band. Specifically, the howling canceller 24 performs fast Fourier transform (FFT) on the audio signal, and determines that howling occurs when a specific frequency component is input without being attenuated for a predetermined time or more. When it is determined that howling has occurred, the notch filter is set so as to suppress the level of the detected frequency band. The notch filter suppresses the level of a predetermined frequency band. Note that the frequency band to be suppressed in the notch filter is variable. Note that any filter may be used as long as it can suppress the level of a predetermined frequency band instead of the notch filter. For example, a parametric equalizer may be used.

  With the configuration as described above, in the third embodiment, acoustic coupling between the audio conference apparatuses can be relaxed, and sound can be emitted at a higher volume.

  FIG. 8 is a block diagram showing the configuration of the audio conference apparatus according to the fourth embodiment. In the figure, the same reference numerals are assigned to components common to the audio conference apparatus shown in FIG. 7, and description thereof is omitted.

  As shown in FIG. 8, the audio conference apparatus 4 includes a microphone 21, a mixing unit 11, an amplifier (AMP) 19, a speaker 22, a limiter (LIMITER) 23, an echo canceller 18, a howling canceller 24, and a delay 25. Yes.

  The delay 25 gives a predetermined delay amount to the input audio signal and outputs it to the audio output terminal. Audio signals are input from the amplifiers 19L and R to the delays 25L and R, respectively. The delays 25L and R give predetermined delay amounts to the audio signals input from the amplifiers 19L and R, respectively, and output the audio signals to the audio output terminals L and R. Thereby, the voice of a conference person is provided to each conference person at the optimal timing. For example, the direct utterance sound of the conference participant 200A is delayed in arrival timing as the conference participant 200A moves away from the conference participant 200A. Therefore, regardless of where the user is present, the directly uttered sound and the sound emitted from the audio conference apparatus can be heard at the same timing. In addition, what is necessary is just to set suitably the delay amount of each audio conference apparatus according to an installation position.

  Note that the number of speakers and the number of microphones are not limited to one. Moreover, you may comprise the speaker array which arranged the some speaker, and the microphone array which arranged the some microphone. When configuring a speaker array or microphone array, the sound output directivity that is strong in a predetermined direction is controlled by controlling the amount of delay to be given to the audio signal supplied to each speaker unit and the collected audio signal collected from each microphone unit. And a sound collecting beam having a strong sound collecting directivity in a predetermined direction can be formed.

It is a block diagram which shows the structure of an audio conference system. It is a block diagram which shows the structure of an audio conference apparatus. It is a figure which shows the connection aspect of an audio conference apparatus. It is a figure which shows an example of the sound collection and sound emission of an audio | voice. It is a block diagram which shows the structure of the audio conference apparatus which concerns on 2nd Embodiment. It is a figure which shows an example of the sound collection and sound emission which concern on 2nd Embodiment. It is a block diagram which shows the structure of the audio conference apparatus which concerns on 3rd Embodiment. It is a block diagram which shows the structure of the audio conference apparatus which concerns on 4th Embodiment.

Explanation of symbols

1-voice conference device 11-mixing unit 19-amplifier 21-microphone 22-speaker

Claims (5)

A plurality of audio signal input sections;
A plurality of audio signal output units;
A sound emission unit that emits an input audio signal;
A sound collection unit that collects sound and generates a collected sound signal;
An input audio signal adding unit that adds the audio signals input from the plurality of audio signal input units and inputs them to the sound emitting unit;
An audio signal superimposing unit that superimposes the collected audio signal on each of the audio signals input from the plurality of audio signal input units, and outputs the superimposed audio signal to the plurality of audio signal output units;
A plurality of audio signal amplifying units that amplify each of the audio signals input from the plurality of audio signal input units or the audio signals output to the plurality of audio signal output units;
An audio conference device.   2. The audio conference according to claim 1, further comprising: a level adjusting unit that attenuates a level of the audio signal to the predetermined threshold when audio signals input from the plurality of audio signal input units have a signal level equal to or higher than a predetermined threshold. apparatus.   An adaptive filter that inputs a sound signal to be input to the sound emitting unit and outputs a pseudo signal of a regression sound signal from the sound emitting unit to the sound collecting unit, and a post that subtracts the pseudo signal from the sound collecting sound signal The audio conference apparatus according to claim 1, further comprising an echo canceller including a processor.   Claims provided with a howling canceller that detects a frequency characteristic of an audio signal input to the sound emitting unit, and performs an attenuation process for attenuating the level of the frequency when the occurrence of the howling and its frequency are detected based on the frequency characteristic. The audio conference apparatus according to claim 1, claim 2, or claim 3.   The audio conference apparatus according to claim 1, further comprising a delay unit that adds a predetermined delay amount to the audio signals output to the plurality of audio signal output units.

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