JP2008294599A - Sound emitting and collecting apparatus and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound emitting and collecting apparatus and system for efficiently suppressing howling when a plurality of devices are installed in the same space. <P>SOLUTION: A sound collecting signal and a sound emitting signal are input to a comparison processing section 8. The comparison processing section 8 obtains the correlation of the sound collecting signal and the sound emitting signal. The comparison processing section 8 sets so that the sound emitting signal is output from a sound emission processing section 7 when the correlation of the sound collecting signal and the sound emitting signal is low. The comparison processing section 8 sets so that the sound emitting signal is not output from the sound emission processing section 7 when the correlation of the sound emitting signal and the sound collecting signal is high. When the correlation is high, the input of a sound collected by another sound emitting and collecting apparatus installed in the same room is judged, and the sound is not emitted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sound emitting and collecting apparatus and a sound emitting and collecting system for collecting sound and emitting sound at a specific point.

  2. Description of the Related Art Conventionally, it has been proposed to place a microphone and a speaker in a room and perform a voice conference at a remote place. When an audio conference is performed, a plurality of microphones or a plurality of the same devices are often installed in one room in order to accurately collect the voice of the speaker. However, when a plurality of microphones or a plurality of devices are installed, the sound output from the speaker easily goes around the microphone, and howling occurs.

In view of this, a loudspeaker system has been proposed in which a microphone and a speaker are arranged in a room and a speaker is detected based on an audio input signal from the microphone (see, for example, Patent Document 1). In a loudspeaker system described in Patent Document 1, when a speaker A existing at a certain position speaks, a microphone installed at a position closest to the speaker A is detected as a sound source position and an audio signal is supplied to another speaker. . On the other hand, when the speaker B existing at another position speaks, the microphone installed at the position closest to the speaker B is detected as the second sound source position, and the gain of the speaker near the speaker B is reduced. Let This suppresses howling.
JP 2006-238254 A

  However, in the loudspeaker system of Patent Document 1, since sound is collected even by a microphone other than the position close to the speaker, howling still occurs when a plurality of microphones are installed in a narrow space.

  Accordingly, an object of the present invention is to provide a sound emission and collection device and a sound emission and collection system that efficiently suppress howling when a plurality of devices are installed in the same space.

  The sound emission and collection device according to the present invention collects sound around the device and outputs a sound collection signal, receives the sound emission signal from another device, and transmits the sound collection signal to the other device. A communication unit to transmit; a sound emission unit that receives the sound emission signal received by the communication unit and emits sound; a comparison unit that obtains a correlation between the sound emission signal and the sound collection signal; and the comparison unit. And a processing unit configured to cause the sound emitting unit to emit sound only when the correlation between the sound emission signal and the sound collection signal is less than a predetermined threshold value.

  In this configuration, the correlation between the sound collection signal and the sound emission signal is obtained, and sound is emitted only when the correlation is low. When the correlation is high, it is determined that the sound collected by another sound emitting and collecting device installed in the same room is input, and the sound is not emitted. Thus, howling can be efficiently suppressed even when a plurality of devices are installed in the same space.

  Further, according to the present invention, the comparison unit compares the level of the sound emission signal and the sound collection signal, and the processing unit has a level of the sound collection signal higher than the level of the sound emission signal in the comparison unit. Only when it is determined that the sound collection signal is output to the sound collection unit.

  In this configuration, the levels of the sound emission signal and the sound collection signal are compared, and if the level of the sound collection signal is higher than the level of the sound emission signal, the sound collection signal is transmitted. When the level of the sound emission signal is high, it is determined that the sound collected by another device has a higher S / N ratio, and the sound of the speaker is collected more accurately, and the sound collection signal is not transmitted. This reduces the load on the network bandwidth.

  The sound emission and collection system according to the present invention is characterized in that a plurality of sound emission and collection devices according to claim 1 or 2 are connected.

  According to the present invention, the correlation between the sound emission signal and the sound collection signal is obtained, and the sound emission signal is emitted only when the correlation is low, so that even when a plurality of devices are installed in the same space, it is possible to efficiently Howling can be suppressed.

  Hereinafter, a sound emission and collection system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a sound emission and collection system. FIG. 2 is a block diagram showing the configuration of the sound emission and collection device.

  In FIG. 1, this sound emission and collection system includes a plurality of sound emission and collection devices 1A to 1D connected via a network. The sound emission and collection devices 1A to 1D are installed in the same space (same room). The sound emission and collection devices 1A to 1D are also connected to sound emission and collection devices installed at other points (rooms). The sound emission and collection devices 1A to 1D all have the same configuration and function, and FIG. 2 shows the configuration of the sound emission and collection device 1A as a representative.

  In FIG. 2, the sound emission and collection device 1A includes a microphone 2, a speaker 3, an echo canceller 4, an input / output interface (I / F) 5, a sound collection processing unit 6, a sound emission processing unit 7, and a comparison processing unit 8. I have.

  In the figure, a front-end amplifier, an A / D converter that digitally converts an analog audio signal, a D / A converter that analog-converts a digital audio signal, and a power amplifier are omitted. In the present embodiment, unless otherwise specified, all audio signals transmitted through the sound emission and collection device 1A are digital audio signals.

  The microphone 2 collects sound around the apparatus and outputs a sound signal (sound collection signal). The collected sound signal output from the microphone 2 is input to the echo canceller 4. The echo canceller 4 removes the echo component of the collected sound signal input from the microphone 2 and outputs it to the sound collection processing unit 6 and the comparison processing unit 8.

FIG. 3 is a block diagram showing the configuration of the echo canceller 4. The echo canceller 4 includes an adaptive filter 41 and an adder 42, and inputs the audio signal (sound emission signal) input from the sound emission processing unit 7 to the adaptive filter 41 and the speaker 3. The adaptive filter 41 performs a filtering process on the sound emission signal, and generates a pseudo regression sound signal that simulates a regression voice signal that circulates from the speaker 3 to the microphone 2. The adder 42 removes the echo component by subtracting the pseudo regression sound signal from the collected sound signal. The collected sound signal from which the echo component has been removed is output to the sound collection processing unit 6. The collected sound signal from which the echo component is removed is input to the adaptive filter 41 and used for updating the filter coefficient.
Although the echo canceller 4 is not an essential component in the present invention, the echo canceller 4 removes echo components by the echo canceller 4 and is therefore suitable when the sound emission and collection device is used for voice conferences.

  The sound collection processing unit 6 outputs the sound collection signal input from the echo canceller 4 to the input / output I / F 5 in the subsequent stage according to the instruction of the comparison processing unit 8.

  The input / output I / F 5 converts the input audio signal into a predetermined protocol and transmits it as audio information to another sound emitting and collecting apparatus. The audio information is transmitted / received by being divided into a plurality of channels assigned to each point. That is, the sound emitting and collecting device at each point occupies any one channel and transmits audio information. By assigning a channel to each point, the destination of the received voice information can be known. When the number of channels is smaller than the number of points, the channels may be occupied in order from the device that transmitted the audio information first. The input / output I / F 5 receives audio information from another sound emission and collection device, converts it into an audio signal (sound emission signal), and inputs it to the sound emission processing unit 7 and the comparison processing unit 8. The audio information output by the input / output I / F 5 is transmitted to the sound emission and collection devices 1B to 1D shown in FIG. 1 and also to the sound emission and collection devices installed in other rooms. Also, the audio information input to the input / output I / F 5 includes not only information transmitted from the sound emission and collection devices 1B to 1D but also information transmitted from the sound emission and collection devices in other rooms.

The sound emission processing unit 7 outputs the sound emission signal input from the input / output I / F 5 to the echo canceller 4 according to the instruction of the comparison processing unit 8. Further, the sound emission processing unit 7 may adjust the level of the sound emission signal, the frequency characteristics, and the like. For example, the volume is increased so that a hearing-impaired person can easily hear the content of the sound. Further, when adjusting the frequency characteristic, for example, correction according to the human auditory characteristic is performed. As human hearing gets older, the high frequency range becomes harder to hear than the mid-low range, and correction is made to compensate for this. For example, correction according to the average auditory characteristic of the 70s and older is performed.
The speaker 3 emits sound based on the sound emission signal input from the echo canceller 4.

  The comparison processing unit 8 obtains the correlation between the sound collection signal and the sound emission signal for each channel. By comparing each channel, whether the sound emission signal is transmitted from a device installed in the room of the own device or whether it is transmitted from a device installed in another room. I can know. The correlation between the collected sound signal and the emitted sound signal is expressed by, for example, a cross-correlation coefficient. FIG. 4 is a diagram illustrating the correlation between the sound collection signal and the sound emission signal. FIG. 4A is a diagram showing a sound collection signal, and FIG. 4B is a diagram showing a sound emission signal. FIG. 3C shows the cross correlation coefficient. The vertical axis of the graphs shown in FIGS. 4A and 4B represents the level, and the vertical axis of the graph shown in FIG. 2C represents the cross-correlation coefficient γ. Moreover, the horizontal axis of the graph shown to the same figure (A)-(C) represents time t.

  FIGS. 3A to 3C show an example in which a plurality of sound emission and collection devices collect sound of the same sound source (for example, user's speech). For example, in FIG. 1, the user 101 utters a sound and the sound is picked up by each device. Here, a processing example of the comparison processing unit 8 of the sound emitting and collecting apparatus 1B closest to the user 101 is shown.

  As shown in FIGS. 2A and 2B, the sound emission signal has a predetermined delay τ with respect to the sound collection signal. This is because the voice of the user 101 is picked up by each device via the acoustic transmission space in the room and the network. Since the sound emission and collection device 1B is closest to the user 101, a delay occurs in the sound emission signal transmitted from the other device.

  In this example, since the sound collection signal and the sound emission signal use the same sound as a sound source, the cross-correlation coefficient increases at a certain timing (for example, τ) and exceeds a predetermined threshold.

  The comparison processing unit 8 determines that the correlation between the sound emission signal and the sound collection signal is high when the cross-correlation coefficient exceeds a predetermined threshold as shown in FIG. Set so that no sound signal is output. When the correlation is high, it is determined that the sound collected by another sound emitting and collecting device installed in the same room is input, and the sound is not emitted. On the other hand, when the cross-correlation coefficient is less than the threshold value, that is, when the correlation between the sound collection signal and the sound emission signal is low, the sound emission processing unit 7 is set to output the sound emission signal.

  Further, the comparison processing unit 8 may perform the following processing. That is, the comparison processing unit 8 compares the levels of the sound emission signal and the sound collection signal. The comparison processing unit 8 is set to output the sound collection signal to the sound collection processing unit 6 only when the level of the sound collection signal is higher than the level of the sound output signal. On the other hand, when the level of the sound emission signal is higher than the level of the sound collection signal, the sound collection signal is set not to be output to the sound collection processing unit 6.

  Since the sound collection signal and the sound emission signal are compared for each channel, for example, when a user in the room of the own device and a user in another room speak simultaneously, only the sound transmitted from the other room is emitted. Can be set to

An example of the operation of the sound emission and collection system is shown in FIGS. 5-7, the same code | symbol is attached | subjected about the structure which is common in FIG. 1, and the description is abbreviate | omitted.
First, as shown in FIG. 5, the sound information is transmitted from the sound emitting and collecting devices in other rooms to the sound emitting and collecting devices 1A to 1D. The input / output I / Fs 5 of the sound emission and collection devices 1A to 1D each generate a sound emission signal from the received audio information. The comparison processing units of the sound emission and collection devices 1A to 1D obtain the correlation between the sound emission signal and the sound collection signal. Here, the sound emission signal is transmitted from a sound emission and collection device in another room, and the correlation with the sound collection signal is low. As a result, all the sound emission and collection devices 1A to 1D emit sound. Thereby, the user 101 can listen to the uttered voices of other rooms. Since sound is emitted from a plurality of devices, it is easy to hear the content of the sound.

  Next, as illustrated in FIG. 6, when the user 101 utters a sound, the microphones 2 of the sound emission and collection devices 1 </ b> A to 1 </ b> D each collect the sound of the user 101 and generate a sound collection signal. The sound collection signal of each sound emission and collection device is transmitted as sound information to the sound emission and collection devices in the room other than the own device. It is also transmitted to sound emitting and collecting devices in other rooms. The comparison processing unit 8 of each of the sound emission and collection devices 1A to 1D obtains the correlation between the sound collection signal of the own device and the sound emission signal (the sound collection signal of another device). When the level of the sound emission signal is low (close to 0), the correlation coefficient is not calculated. Here, since the two signals are both voices of the user 101, the correlation is high. As a result, the sound emission and collection devices 1A to 1D do not emit sound. Thereby, even when a plurality of sound emitting and collecting apparatuses are installed in the vicinity of the same room, howling can be efficiently suppressed.

  In addition, when the correlation is high, when the comparison processing unit 8 compares the levels of the sound collection signal and the sound emission signal, the operation is as shown in FIG. When the user 101 utters a sound, the microphones 2 of the sound emission and collection devices 1A to 1D each collect the sound of the user 101 and generate a sound collection signal. At this time, since the sound emission and collection device 1B is installed at a position closest to the user 101, the sound emission and collection device 1B first generates a sound collection signal and outputs it to another device.

  The sound collection signal output by the sound emission and collection device 1B is transmitted to the other sound emission and collection devices 1A, 1C, and 1D as audio information. It is also transmitted to sound emitting and collecting devices in other rooms. The comparison processing unit 8 of the sound emission and collection devices 1A, 1C, and 1D obtains a correlation between the sound collection signal of the own device and the sound emission signal input from the sound emission and collection device 1B (the sound collection signal of the sound emission and collection device 1B). In this case, since the two signals are both voices of the user 101, the correlation becomes high. Thereafter, the comparison processing unit 8 of the sound emission and collection devices 1A, 1C, and 1D compares the sound emission signal input from the sound emission and collection device 1B with the level of the sound collection signal of the own device. Since the sound emission and collection devices 1A, 1C, and 1D are installed at positions farther from the user 101 than the sound emission and collection device 1B, the level of the sound emission signal is higher than the level of the sound collection signal. Therefore, the comparison processing unit 8 of the sound emission and collection devices 1 </ b> A, 1 </ b> C, and 1 </ b> D is set so as not to output the sound collection signal to the sound collection processing unit 6. The sound emission signal input from the device in the other room is emitted because the correlation with the sound collection signal of the own device is low, and the sound emission device 1B has a high sound emission signal level. A collected sound signal is output. As a result, only the sound collection signal of the sound emission and collection device 1B is transmitted to the other rooms, and the load on the network band can be reduced. In addition, since the sound collected by the sound emitting and collecting apparatus closest to the speaker position is transmitted to another room, the sound having the best S / N ratio is transmitted.

  As described above, according to the sound emission and collection system of the present embodiment, the correlation between the sound emission signal and the sound collection signal is obtained, and the sound emission signal is emitted only when the correlation is low. Thus, howling can be efficiently suppressed even when a plurality of sound emission and collection devices are installed. Further, the load on the network band can be reduced by comparing the levels of the sound emission signal and the sound collection signal and outputting the sound collection signal only when the level of the sound collection signal is high.

  A plurality of microphones 2 and speakers 3 may be provided. Further, a microphone array in which a plurality of microphone units are arranged, or a speaker array in which a plurality of speaker units are arranged may be used. When the speaker array is used, the directivity of sound emission can be controlled by controlling the delay amount of the audio signal supplied to each speaker unit by the sound emission processing unit 7.

It is a block diagram which shows the structure of a sound emission and collection system. It is a block diagram which shows the structure of a sound emission and collection apparatus. 2 is a block diagram showing a configuration of an echo canceller 4. FIG. It is a figure which shows the correlation with a sound emission signal and a sound collection signal. It is a figure which shows an example of operation | movement of a sound emission and collection system. It is a figure which shows an example of operation | movement of a sound emission and collection system. It is a figure which shows an example of operation | movement of a sound emission and collection system.

Explanation of symbols

1-sound emitting and collecting device 2-microphone 3-speaker 4-echo canceller 5-input / output I / F
6-Sound collection processing unit 7-Sound emission processing unit 8-Comparison processing unit

Claims (3)

A sound collection unit that collects sound around the device and outputs a sound collection signal;
A communication unit that receives a sound emission signal from another device and transmits the collected sound signal to the other device;
The sound emission unit that receives the sound emission signal received by the communication unit and emits sound;
A comparison unit for obtaining a correlation between the sound emission signal and the sound collection signal;
A processing unit configured to cause the sound emission unit to emit sound only when the correlation between the sound emission signal and the sound collection signal is less than a predetermined threshold in the comparison unit;
A sound emission and collection device. The comparison unit compares the level of the sound emission signal and the sound collection signal,
The processing unit is set to output the sound collection signal to the sound collection unit only when the comparison unit determines that the level of the sound collection signal is higher than the level of the sound emission signal. Sound emitting and collecting device.   The sound emission and collection system formed by connecting a plurality of sound emission and collection devices according to claim 1 or 2.

Images