JPS63217865A - Conference communication equipment - Google Patents

Abstract

PURPOSE:To generate a sound image with presence at a caller terminal equip ment of the reception side when plural talking terminal equipments are busy at the same time by selecting number of plural electroacoustic transducers as a specific relation to the number of opposite talking terminal equipments and including a sound image position setting means to a control means. CONSTITUTION:The number P of amplifiers 5-1-5-P and loudspeakers 6-l-6-P is selected to be (N+1)/2<=P<=N/2+1, where N is the number of opposite talking terminal equipments. A control circuit 4 controls a processing circuit 3 and when a voice signal is sent from one terminal equipment, the sound image with different location is caused to each terminal equipment according to the received control information. Thus, the location of the sound image in this case is selected to be any position of the loudspeakers 6-1-6-P or two intermedi ate locations adjacent to each other in the loudspeakers 6-1-6-P. Moreover, in selecting the location of sound image to nearly the center of the positions corresponding to the talking terminal equipments, the presence is further en hanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applied to a conference call device disposed at a plurality of caller terminals interconnected by a conference call audio line. In particular, the present invention relates to sound image position recognition for identifying transmission light from a plurality of callers at individual caller terminals.

[Conventional technology]

In a conference call device, it is desired to generate sounds in different locations for each caller in order to identify the caller who is currently talking and to obtain the atmosphere of a general conference.

As such a conference call device, a device has been proposed that distributes a plurality of callers to two destinations and transmits and reproduces a sound image (an image of the caller's sound source) using a stereo system. An example of such a device is Minami, "Audio system of teleconference system using pseudo-stereo audio", Institute of Electrical Communication Engineers, Circuits and Systems Research Circular CAS 86-29.
Explained in 1986.

FIG. 4 shows a block diagram of a conventional conference call device.

In this figure, two caller terminals are shown with a transmitter and a receiver, respectively.

The right microphone 41 and the left microphone 42 convert the speaker's voice into electrical signals. Transfer function calculation circuit 44
calculates a transfer function of the difference between the right microphone 41 and the left microphone 42 and sends this transfer function via a control information line 45 provided separately from the audio line 43. On the receiving side, a transfer function reproducing circuit 46 reproduces another channel from a signal in which the audio information and the reception transfer function are combined, and a right loudspeaker 47 and a left loudspeaker 48 reproduce a sound image. To find the transfer function, right microphone 41 and left microphone 4
Find the correlation coefficient of the audio signal with 2.

However, in this conference call method, fundamentally, ■ When multiple people are transmitting at the same time (there are multiple transmitters in Figure 4) or when the transmitter moves, it is difficult to accurately calculate the transfer function. As described in the audio quality evaluation test results in the above-mentioned document, in pseudo-stereo, the left and right level ratio becomes unnatural. Although it is assumed that in a teleconference (remote communication conference), it is desirable to connect not only between two terminals but also between two or more terminals, the above principle and the conventional right channel and left channel The stereo system, in which the sound field is reproduced by independently transmitting the signals, has the disadvantage that it is impossible in principle to generate a pseudo-stereo sound field in a conference call system that connects three or more destinations.

In order to solve these drawbacks, the applicant has already filed a patent application for an invention related to a conference call system in which caller terminals are placed at multiple locations and sound images are generated at different positions for each caller terminal. (Patent application 1986-332)
28, hereinafter referred to as the "prior invention"). In this prior invention,
Multiple caller terminals are connected via an audio line, and the caller terminal on the sender side transmits control information indicating the origin of the call along with the audio signal, and the caller terminal on the receiver side transmits multiple calls according to the received control information. A loudspeaker is used to generate a sound image at a different location for each caller's terminal.

[Problem that the invention seeks to solve]

However, the system of the prior invention requires the same number of loudspeakers as the number of callers;
When multiple caller terminals are transmitting at the same time, if the audio signals are added and transmitted over the audio line, the loudspeakers will sound at the same time, and on the receiver's side, there will be a When a sound image is generated and the state of the conversation changes from one person to multiple people, the position of the sound image moves, giving the listener a strange feeling.

Furthermore, a method of generating multiple sound image positions using two loudspeakers is proposed by Kurosumi et al., "Spatial impression of sound image and its control method by two-channel speaker reproduction," NHK Technical Research Vol.
As stated in Volume 8, No. 1 (1986), the position of the front layer may be blurred due to the reverberation characteristics of the conference quality where the loudspeaker is installed, so it is difficult to improve the resolution of the sound image position by ground identification. , this method is not preferred.

The present invention solves the above-mentioned problems and provides a conference call device that can generate a realistic sound image on a receiver's terminal when a plurality of terminals are transmitting at the same time. The purpose is to

[Means for solving problems]

The conference call device of the present invention is arranged in a caller's terminal connected to an audio line for conference calls, and includes means for transmitting control information indicating a transmission source together with a transmitting audio signal, and a means for transmitting control information indicating a transmission source along with a transmitting audio signal, and a means for transmitting control information indicating a transmission source from a received audio signal. and a reproduction means for reproducing audio, the reproduction means controlling the relative volume of the plurality of electroacoustic transducers based on the received control information, and controlling the relative volume of the plurality of electroacoustic transducers for each terminal of the other party. In the conference call device including a control means for generating sound images at different positions, the number P of the plurality of electroacoustic transducers is in a relation to the number N of the terminals of the other party, and the control means: The present invention is characterized in that it includes a sound image position setting means for generating a sound image at the position of one electroacoustic transducer or at a position intermediate between two electroacoustic transducers.

The sound image position setting means is configured to provide, when a plurality of caller terminals are transmitting calls at the same time, a sense of spaciousness of the sound image in proportion to the number of caller terminals at the center of the position corresponding to these caller terminals. This is desirable.

[For production]

When a voice signal is being transmitted from one caller terminal, the conference call device of the present invention generates a sound image at a different position for each caller terminal according to the received control signal. At this time, the sound image generation position is controlled to be the position of each electroacoustic transducer or the intermediate position between two electroacoustic transducers. As a result, sound images of each caller are generated in a pseudo manner at respective positions on the conference table set in advance for each caller. Therefore, it becomes possible to identify which of the callers is currently speaking.

Furthermore, when multiple caller terminals are transmitting audio signals at the same time, the sound image generation position is set to approximately the center of the positions corresponding to those caller terminals, giving a pseudo sound spread. This can enhance the sense of realism. Therefore, it is possible to create an atmosphere similar to that of a general meeting.

〔Example〕

FIG. 1 shows a block diagram of a receiving section of a conference call device according to an embodiment of the present invention.

This conference call device is placed at each caller's terminal, and each is connected to an audio line 1 for conference calls.

The processing circuit 3 is supplied with audio signals from the audio line 1, and the control circuit 4 is supplied with control information from the control line 2. The processing circuit 3 is connected to a loudspeaker 6-1 via amplifiers 5-1 to 5-P.
~6-P is connected. The control circuit 4 is connected to the processing circuit 3.

The number P of each of the amplifiers 5-1 to 5-P and the loudspeakers 6-1 to 6-P has the following relationship when the number of caller terminals is N.

The control circuit 4 controls the processing circuit 3, and when a voice signal is being transmitted from one caller terminal, it generates a sound image having a different position for each caller terminal according to the received control information. At this time, the sound image generation position is the loudspeaker 6-
Any position from 1 to 6-P, or loudspeaker 6-1 to 6
−P so that the position is between two adjacent ones of P. Therefore, it becomes possible to identify which of the callers is currently speaking.

Further, when a plurality of caller terminals are transmitting audio signals simultaneously, the control circuit 4 sets the sound image generation position to approximately the center position of the positions corresponding to those caller terminals,
Furthermore, it gives a pseudo sound spread. This increases the sense of realism and creates an atmosphere similar to that of a general meeting.

In the following, a case where the number of ground connections is six will be explained as an example.

FIG. 2 shows an example of loudspeaker arrangement and sound image position. Since the number of ground connections is 6, the number N of other party's terminals is 5.
, and the number of loudspeakers P is three. The sound image is displayed at position 2 of the loudspeakers 6-1 to 6-3, corresponding to the caller's terminal that is transmitting a call.
1.23.25, position 22 between loudspeakers 6-1 and 6-2, or position 24 between loudspeakers 6-2 and 6-3
is generated.

FIG. 3 is a block diagram showing an example of the processing circuit 3. As shown in FIG.

The audio line 1 is connected directly to a variable attenuation circuit 31.33.35 and via a phase shift circuit 30 to a variable attenuation circuit 32.3.
Connected to 4.36. Variable attenuation circuits 31.32 are connected to amplifier 5-1, variable attenuation circuits 33.34 are connected to amplifier 5-2, and variable attenuation circuits 35.36 are connected to amplifier 5-1.
-3 is connected. The amount of attenuation of the variable attenuation circuits 31 to 36 is controlled by the control circuit 4. By controlling this amount of attenuation, the volume of each loudspeaker can be adjusted and the position of the sound image can be set.

Although not shown, this conference call device includes means for transmitting control information indicating the transmission source together with the transmitted voice signal.

As an example of such control information, a case will be explained in which control information with a number of bits equal to the number M of caller terminals is used, and the caller terminal that is the sender transmits the bit corresponding to its terminal number as "1". do. The present applicant has already filed an application for an invention regarding the code structure and code processing in such control information (Japanese Patent Application No. 61-186674).

This code structure is shown in Table 1.

(Hereinafter, the margin of this page) Table 1 The configuration and control method of the means for transmitting this control information will be explained with reference to Table 1.

When a certain caller's terminal becomes the originator, the caller's terminal
Control information whose pre-assigned number bit is "1" is transmitted to the control information line. For example, the number "1"
"When the caller's terminal becomes the source of the call, the caller's terminal becomes r
Send OOO-01J as control information. Furthermore, when the caller terminal with number "2" becomes the sender, that caller terminal transmits "0O-010J as control information. The caller terminal that is not the sender sends [000-...OOJ Send.

At this time, on the control line 2, the control information from each caller terminal is overlapped, and the logical sum thereof is transmitted. Therefore, for example, when two caller terminals with number "1" and number "2" are the originators, control information of "00...01)" is supplied to the other caller terminals. be done.

When receiving such control information in the form of a binary code sequence, the conference call device of each caller terminal first identifies from the code sequence whether there is one or multiple transmission sources.

When there is only one transmitter, a sound image is generated at a preset position in the conference call device on the receiving side. The placement of the sound image and its control method are described in detail in Kurozumi, ``Sound Image Spreading and Distance J, NHK Giken Monthly Report, May 1985 issue.In other words, the sound image is placed between two loudspeakers. When generating , the volume of each of the two loudspeakers is set to 1/2 when the reference listening volume level is set to "1". Also, when generating a sound image on the right side, set the volume of the right loudspeaker to "1" and set the volume of the other loudspeakers to "0".
Control so that

In a conference call, only one caller's terminal is not necessarily the source of the call, and there are often multiple sources of communication due to laughter, mutual agreement, etc. In this case, the binary code received from the control information line includes at least a plurality of logic "1" codes. Therefore, the above-described control cannot determine the sound image generation position. In such a case, a sound image is generated at the center of the position corresponding to the caller terminal of the sender by giving a sound image spread proportional to the number of callers.

For information on how to obtain a wide sound image with a single sound, see Schreuda, "An Artificial Stereophone Effect of a Single Audio Signal," J.A.E. Varnish Volume 6 No. 2 (1958) Page 74 (rAn Ar
tificial 5tereophonic Eff
ectobtained front a Singl
Audio SignalJ J, A, E, S, +Vo
1.6. No, 2. p74+ 1958). Therefore, as shown in FIG. 3, by combining the output signal of the phase shift circuit 30 and the input signal, it is possible to achieve sound spread. When a plurality of speech sources exist, the position and spread of the sound image can be controlled by controlling the amount of attenuation of the variable attenuation circuits 31 to 36.

Tables 2 to 5 show control examples of the variable attenuation circuits 31 to 36 in cases where the number of transmission sources is different.

Here, as reception control information, control information from which bits assigned to the own caller terminal are removed is shown.

(Hereinafter, this page margin) In order to control the amount of attenuation of the variable attenuation circuits 31 to 36, it is convenient to use a read-only memory in the control circuit 4. That is, the binary code of the received control information is used as an address signal of the read-only memory, and the attenuation amount of each of the variable attenuation circuits 31 to 36 is stored for each address.

Table 6 shows examples of read-only memory output codes for address signals. As the address signal, control information from which bits assigned to the own caller's terminal are removed is used. The output code "00" corresponds to the attenuation amount in OdB, and "01" and "1)" correspond to 3 dB and 40 dB, respectively.

(Hereinafter, this page margin) In addition, since semiconductor integrated circuits that variably control the amount of attenuation of analog signals in response to double code control signals are commercially available, such integrated circuits can be used to implement variable attenuation circuits 31 to 31. 3
6 can also be configured.

Through such an operation, the position of the other party is arbitrarily set in advance in a table in the read-only memory, and when there is only one calling party, the attenuation amounts of the variable attenuation circuits 31 to 36 are controlled to place the sound image at one position. When there are a plurality of speakers, the attenuation amounts of the variable attenuation circuits 31 to 36 and the output signal of the phase shift circuit 30 are used together to obtain a sound image in which a plurality of speakers are the speakers at the same time.

〔Effect of the invention〕

As described above, the conference call device of the present invention can generate sound images in virtually any arrangement using loudspeakers that are approximately half the number of caller terminals.

This makes it easier to identify callers and has the effect of enriching the atmosphere of the conference.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a receiving section of a conference call device according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of loudspeaker arrangement and sound image position. FIG. 3 is a block diagram showing an example of a processing circuit. FIG. 4 is a block diagram of a conventional conference call device. 1... Audio line, 2... Control line, 3... Processing circuit, 4... Control circuit, 5-1 to 5-P... Amplifier,
6-1 to 6-P... Loudspeaker, 30... Phase shift circuit, 3
1 to 36... Variable attenuation circuit, 41... Right microphone, 42... Left microphone, 43... Audio line,
44... Transfer function calculation circuit, 45... Control information line, 46... Transfer function reproduction circuit, 47... Right loudspeaker,
48...Left loudspeaker.

Claims (2)

[Claims] (1) A means for transmitting control information indicating the transmission source together with the transmitting audio signal, which is placed in the caller's terminal connected to the audio line for the conference call, and a playback device for reproducing the caller's voice from the received audio signal. means, the reproduction means includes a plurality of electroacoustic transducers, and controls the relative volume of the plurality of electroacoustic transducers based on the received control information to produce sound images at different positions for each terminal of the other party. In the conference call device, the number P of the plurality of electroacoustic transducers is (N+1)/2≦P≦(N/2)+1 with respect to the number N of the other party's terminals. The conference call device is characterized in that the control means includes a sound image position setting means for generating a sound image at the position of one electroacoustic transducer or at a position intermediate between two electroacoustic transducers. (2) When a plurality of caller terminals are transmitting at the same time, the sound image position setting means provides a sense of spaciousness of the sound image in proportion to the number of caller terminals at the center of the position corresponding to these caller terminals. A conference call device according to claim 1, which is a configuration.