JPH06350486A - Sound communications system - Google Patents

Abstract

PURPOSE:To provide a stiff sound communications system capable of preventing an echo and howling, etc., from occurring. CONSTITUTION:This system is a sound communications system which performs the transmission/reception of sound control information 8 in real time simultaneously with the transfer of a sound signal between each device and controls by monitoring an opposite device and the state of a sound loop including acoustic coupling 7A(7B) in the sound communications system which performs communication with a remote place by using devices equipped with a sound detection amplifier means 4A(4B) which sends out the sound signal acquired by a microphone 1A(1B) to a transmission line 3, sound amplifier means 5A(5B) which generates sound from the sound signal inputted from the transmission line, and a sound control means 6A(6B) which controls the level and frequency characteristic of the sound signal to be sent to and inputted from the transmission line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic communication system which can be used in, for example, a communication conference device.

[0002]

2. Description of the Related Art FIG. 4 shows a block diagram for explaining a conventional acoustic communication system. In the figure, 10A and 10B indicate devices installed at remote locations. These devices 10A and 10B
Are connected by a transmission line 3 in a state in which a call can be made. The devices 10A and 10B are microphones 1A (1B), respectively.
The acoustic detection and amplification means 4A (4B) that sends out the acoustic signal captured by the above to the transmission path 3, and the acoustic amplification means 5 that outputs the acoustic signal input from the transmission path 3 from the speaker 2A (2B).
A (5B), and acoustic control means 6A (6B) for controlling the acoustic signal to be sent to the transmission path 3 and the level, frequency characteristics, etc. of the acoustic signal input from the transmission path 3. Reference numerals 7A and 7B denote acoustic coupling between the speaker 2A (2B) and the microphone 1A (1B) in the room.

The sound control means 6A (6B) is provided with a voice switch, an echo canceller and the like. The voice switch provides an appropriate loss to the acoustic detection / amplification means 4A, 4B according to the level of the input signal and the level of the output signal, suppresses howling, and secures the call (for example, N.
TT Research Practical Report Vol. 37, No. 2 (1988) Voice conferencing device using band division type voice switch, Oikawa et al.). Regarding the echo canceller, acoustic coupling 7A (7B)
The sound control means 6A (6B) detects that the sound emitted from the speaker 2A (2B) is reflected and delayed and is input to the microphone 1A (1B) as an acoustic echo, and the means 4A, 4B and 5A, In 5B, appropriate signal processing is performed and the signal is transmitted to the partner device. (For example, NTT
Research Practical Use Report Vol. 37, No. 2 (1988) Audio conference device using multiple echo echo cancellers, Oikawa et al.

In any case, conventionally, the device 10 is basically the same.
Only the acoustic space with A and 10B is controlled. When the transmission line 3 is a two-wire type analog line, a line echo is generated by the hybrid transformer used when performing the two-wire to four-wire conversion. We have also compensated for this line echo, but with the recent digitization of the transmission line 3,
There is a situation where it is sufficient to control only acoustic echo.

[0005]

The sound control means 6A (6
The echo canceller, the voice switch, etc. provided in B) only perform the acoustic control on the device side. In other words, there is a problem that it is not possible to follow changes in the acoustic conditions of the communication partner that change from moment to moment, howling and echo are allowed to occur, and it is difficult to secure a call.

[0006]

According to the present invention, acoustic detection and amplification means for transmitting an acoustic signal captured by a microphone to a transmission path, acoustic amplification means for emitting an acoustic signal input from the transmission path as sound, and transmission path In an acoustic communication system in which communication is performed between remote locations by using an apparatus equipped with an acoustic control means for controlling the level, frequency characteristics, etc. of the acoustic signal to be transmitted to and the acoustic signal input from the transmission path, We propose an acoustic communication system characterized by transmitting and receiving acoustic control information in real time at the same time as transmitting acoustic signals, and monitoring and controlling the state of the acoustic loop including the other party's device.

According to the acoustic communication system of the present invention, since acoustic control information can be shared among the devices, not only the own device but also the entire acoustic loop including the acoustic coupling of the other party can be monitored and controlled. . As a result, acoustic control can be performed in response to changes in the acoustic environment on the remote side, so howling and echo can be prevented from occurring, and telephone conversations can be secured reliably, enabling robust acoustic communication control. Become.

Further, according to the present invention, in the acoustic communication system claimed in claim 1, there is provided means for detecting a frequency at which the loop gain in the entire loop including the device on the other side and the acoustic coupling exceeds a predetermined value, and this detecting function. We propose an acoustic communication system that adds a means for reducing the gain of the detected frequency.
According to this acoustic communication system, howling frequency can be predicted before howling occurs. Therefore, howling can be suppressed by inserting an appropriate loss in the detected frequency and reducing the gain. .

Further, the present invention proposes a transmission / reception transmission mode of acoustic control information. As the transmission / reception transmission mode of the acoustic control information, the direct multiplex transmission method proposed in claim 3 and claim 4
The separation transmission method proposed in 1) is considered. The direct multiplex transmission system proposed in claim 3 is a system in which acoustic information of the own device is embedded in an acoustic signal and separated on the receiving side. The separate transmission system proposed in claim 4 is a system for simultaneously transmitting an acoustic signal and acoustic control information on a separate line, and as the transmission mode, logical multiplexing by packets, physical multiplexing and the like can be applied.

[0010]

1 is a block diagram for explaining an acoustic communication system according to the present invention. Reference numeral 10A shown in FIG.
(10B), 1A (1B), 2A (2B), 3, 4A
All of (4B), 5A (5B), and 6A (6B) are the same as those described with reference to FIG. In this invention, the sound control means 6A, 6B
, The sound control information 8 of the other party is exchanged and shared.

As the acoustic control information, control information such as a voice switch, level monitoring information, frequency characteristics of an acoustic loop, reverberation time and the like are exchanged between the acoustic control means 6A and 6B and shared with each other. Further, as the value-added information, spatial sound source position, sound source direction information, and the like can be transmitted and received to enable reproduction of the sound source position. 2 and 3 each device 10A, 1
An example of the frequency response at 0B is shown. FIG. 2 shows an example of a steady state. In this steady state, the frequency response between the devices 10A and 10B does not cause howling because the loop gain does not exceed 1.

The example of FIG. 3 shows that in the apparatus 10A, the state of the room changes and the frequency response changes from the state of the solid line to the state of the broken line. Along with this, although depending on the phase characteristic of the system, the loop gain exceeds a predetermined value, for example 1, at the frequency P, and howling occurs. Since the sound control means 6A and 6B transmit and receive the frequency response of each other at any time, the sound control means 6A is the sound control means 6 on the other side.
Both the frequency response from B and the frequency response in the device 10A can be monitored, and the howling margin can be calculated in the process of changing the frequency response in the device itself. Therefore, it becomes possible to predict the howling frequency before the howling occurs, so that the device 10A uses the means 4A and 5A.
Is controlled and a proper loss is inserted in the frequency P, howling suppression control can be performed.

The transmission form of the acoustic control signal 8 may be (a) direct multiplex transmission system or (b) separated transmission system, depending on the relationship with the acoustic signal. The direct multiplex transmission method (a) is a method in which the transmission line 3 is shared by an acoustic signal and an acoustic control signal. In other words, it refers to a multiplex transmission system in which the acoustic control signal is embedded in the acoustic signal and separated on the receiving side. The separated transmission method of (b) refers to a method of transmitting the acoustic control signal on another line,
For example, it can be multiplexed with a control signal of another line and transmitted on a control line. As a multiplexing method, logical multiplexing by packets, physical multiplexing, etc. can be considered.

[0014]

As described above, by using the acoustic communication system according to the present invention, the acoustic control signal is shared between the devices at the same time as the acoustic signal, so that the acoustic condition of the communication partner that changes from moment to moment can be controlled. It becomes possible to follow the change, the call is kept secured, and more robust acoustic communication becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a frequency characteristic diagram for explaining the operation of the present invention.

FIG. 3 is a frequency characteristic diagram for explaining the operation of the present invention.

FIG. 4 is a block diagram for explaining a conventional technique.

[Explanation of symbols]

 1A, 1B Microphones 2A, 2B Speakers 3 Transmission lines 4A, 4B Acoustic detection amplification means 5A, 5B Acoustic amplification means 6A, 6B Acoustic control means 7A, 7B Acoustic coupling 8 Acoustic control signals

Claims (4)

[Claims] 1. A sound detection / amplification means for transmitting an acoustic signal captured by a microphone to a transmission path, an acoustic amplification means for emitting an acoustic signal input from the transmission path as a sound, an acoustic signal and a transmission path for transmission to the transmission path. In an acoustic communication system that performs communication between remote locations using a device equipped with an acoustic control unit that controls the level, frequency characteristics, etc. of the acoustic signal input from the An acoustic communication system characterized in that the acoustic control information is transmitted and received by the device, and the state of the device on the other side and the state of the acoustic loop including acoustic coupling are monitored and controlled. 2. The acoustic communication system according to claim 1, wherein
A sound characterized by adding a means for detecting a frequency at which the loop gain in the entire loop including the device on the other side and the acoustic coupling exceeds a predetermined value, and a means for reducing the gain of the frequency detected by this detection function. Communication method. 3. An acoustic communication system, wherein the acoustic control information according to claim 1 is multiplexed and transmitted together with an acoustic signal. 4. An acoustic communication system, wherein the acoustic control information according to claim 1 is transmitted through an independent transmission path.