JP3314730B2 - Audio playback device and communication conference device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention adjusts an attenuation characteristic of a sound reproduced from a speaker depending on a distance, simulates an attenuation characteristic of a sound emitted from a sound source at a position deeper than the speaker, and adjusts the attenuation characteristic of the sound from the sound source. The present invention relates to an audio reproducing device for reproducing emitted sounds and a communication conference device using the audio reproducing device.

[0002]

2. Description of the Related Art The sound pressure level of a sound emitted from a point sound source or a speaker is attenuated in inverse proportion to the square of the distance from the position where the sound is emitted, according to the so-called inverse square law. I do. For this reason, assuming a sound source at a position deeper than the speaker and trying to reproduce the attenuation characteristics of the sound emitted from that position with the sound reproduced from this speaker,
Previously, it could not be realized.

[0003] The teleconference system allows two-way communication of audio signals and, if necessary, video signals between rooms at two separate points so that a conference can be held in an atmosphere as if they were in one connected room. Things. In this case, if it is heard that the voice of the other party is speaking further in the room than they are, the sense of presence is increased. However, in reality, since the speaker that reproduces the voice of the other party is in the room where they are located, it was not possible to reproduce the attenuation characteristics of the sound emitted from the back. Due to such a problem, the conventional communication conference system still lacks a sense of reality.

[0004] Further, since the degree of change in sound pressure level is different between a place very close to the speaker and a place slightly away from the speaker, if the reproduction volume is adjusted just right for a person close to the speaker, it is difficult for a person slightly away from the speaker. If the volume is low, it will be difficult to hear. Conversely, if you adjust the playback volume so that it is just right for people who are a little away from the speaker,
It sounded loud for those who were very close to the speakers. For this reason, in the conventional communication conference system, it was difficult to adjust the reproduction volume.

The present invention solves the above-mentioned problems in the prior art, adjusts the attenuation characteristic of sound reproduced from a speaker, and imitates the attenuation characteristic of sound emitted from a sound source at a position deeper than the speaker. Then, the sound reproducing apparatus capable of reproducing the sound emitted from the sound source and the sound reproducing apparatus are used to increase the sense of realism and to reduce a sudden change in the sound pressure level due to the distance from the speaker. It is an object of the present invention to provide a communication conference device that facilitates volume adjustment.

[0006]

According to the present invention, there is provided an audio reproducing apparatus comprising: a first speaker disposed substantially facing a listener; and a diagonally upper part of the first speaker positioned obliquely above the first speaker. Signal processing for supplying an audio signal to the second speaker and the first speaker and reproducing the same, and supplying a second speaker with a signal obtained by delaying the audio signal in a time range in which no echo is generated. And an apparatus.

According to the speaker arrangement of the audio reproducing apparatus, the first speaker is arranged at a position substantially facing the listener, whereas the second speaker is arranged substantially above the first speaker. Since it is located diagonally above,
The distance from the second speaker to the listener is always longer than the distance from the first speaker to the listener. Moreover, when the listener moves in the front-rear direction with respect to the first speaker, the amount of change in the distance from the speaker to the listener is the amount of change in the distance from the first speaker to the amount of movement of the listener itself. On the other hand, the amount of change in the distance to the second speaker is smaller than the amount of change in the distance to the first speaker because the second speaker is above. Therefore, the attenuation characteristic of the sound reproduced from the second speaker is gentler in the attenuation characteristic with respect to the distance from the first speaker than the attenuation characteristic of the sound reproduced from the first speaker. Therefore, by reproducing the same sound from the first and second speakers, the attenuation characteristic is made gentler than when the sound is reproduced from only the first speaker, and the sound source at a position farther than the first speaker is reproduced. be able to. However, when the sound is reproduced from the first and second speakers at the same time, the sound image moves upward and is localized. Therefore, by slightly delaying the sound reproduced from the second speaker, the Haas effect (preceding sound effect) is generated. This prevents the sound image from moving upward.
As described above, by using the first and second speakers, the sound emitted from the sound source can be reproduced by imitating the attenuation characteristics of the sound emitted from the sound source located at a position deeper than the first speaker.

The output sound pressure level of the audio signal reproduced from the second speaker is determined by the sound image of the audio signal.
By increasing the sound pressure level of the audio signal reproduced from the first speaker within a level range not localized in the direction of the speaker, and reproducing these audio signals, the effect of the second speaker is enhanced. The sound emitted from the sound source at a position deeper than the first speaker can be reproduced by making the attenuation characteristic more gentle.

Further, the communication conference apparatus of the present invention is an apparatus for holding a conference between two points separated from each other, and is arranged at each of these points almost facing an attendee (speaker and listener). A first speaker, a second speaker arranged obliquely above the attendant above the first speaker, a microphone arranged at an appropriate position, and a sound signal supplied to the first speaker. And a signal processing device that supplies a signal obtained by delaying the audio signal in a time range that does not cause an echo to the second speaker and reproduces the signal. The audio signal is transmitted to the signal processing device at the other point via a transmission path, and the time difference due to the delay is generated and reproduced from the first and second speakers at the other point. Sound picked up by the microphone The first one point said by transmitting signals via a transmission path to the signal processing device of one point, in which the second speaker formed by play caused a time lag due to the delay.

[0010] According to the communication conference apparatus of the present invention, the attenuation characteristic of the voice of the other party can be made closer to the attenuation characteristic of sound emitted from a position farther than the first speaker. , The sound pressure level becomes the same as when the voice of the other party is speaking from the back of the room in which they are located, and the sense of presence can be increased. In addition, since a sudden change in the sound pressure level due to the distance from the speaker is reduced, it is easy to hear at any position in the room, and the reproduction volume can be easily adjusted.

The microphone is arranged facing the attendee, and the voice of the attendant is collected at a sound pressure level corresponding to the distance from the microphone and reproduced in the room of the other party. Can be reproduced in the front-rear direction.
However, the distance between the microphone and the participant is shorter than the distance from the participant in one room to the participant in the other room to be reproduced in the room of the other party, and the sound pressure level of the picked-up signal according to the position of the participant is Fluctuations increase. In this regard, by arranging the microphone not above the participant but above the participant (substantially above the first speaker), the distance between the microphone and the participant is increased, and sound is collected according to the position of the participant. The variation in the sound pressure level of the signal can be reduced, and the sense of distance from the attendee in one room to the attendant in the other room to be reproduced in the other room can be reduced.

At each point, the combination of the first and second speakers and the microphone is disposed at substantially the same position in the left and right direction on the wall surface in the room, and the combination of the first and second speakers and the microphone is arranged. A plurality of combinations are arranged at appropriate intervals in the left-right direction of the wall surface, and the pairs facing each other at the two points are combined with each other to transmit and reproduce the collected audio signal between the pairs. Thereby, the sound image localization in the left-right direction is obtained, and the positional relationship in the left-right direction between the participant in one room and the participant in the other room can be reproduced.

Further, by arranging the first and second loudspeakers and the microphone on a sound absorbing wall formed by arranging a sound absorbing material on a wall in the room, the voice of the attendee can be heard in front of the attendee's room. The light does not reflect off the wall, so that the presence of the front wall is no longer felt, and the sense of unity with the room of the other party can be enhanced.

[0014] Further, at each point, a television camera arranged substantially facing the attendee, and at least a first speaker and a television camera are arranged so as to cover the front of the television camera.
An acoustically permeable screen in which a window is formed at the lens position of the TV camera and a video projector for projecting an image on the screen are arranged, and the signal processing device at each point shoots with the TV camera at one point. The video signal transmitted to the other point via the transmission path, is projected from the video projector at the other point to the screen at the other point, and the video signal captured by the television camera at the other point is transmitted through the transmission path. Via a video projector at the one point on the screen at the one point, thereby improving the sense of unity with the room of the other party. It can be performed.

[0015]

Embodiments of the present invention will be described below. FIG. 2 shows an example of a speaker arrangement according to the present invention. In the room 10, a position facing the listener 12 on the wall surface 14 in front of the listener 12 (exactly, a position at the height of the head of the listener 12 and separated horizontally forward from the head) ), The first speaker 16 is disposed in the horizontal direction toward the listener 12. Further, a second speaker 18 is arranged in a horizontal direction substantially directly above the first speaker 16 and obliquely above the listener 12 toward the listener 12. The first and second speakers 16 and 18 have, for example, the same characteristics.

Assuming that the distance from the first speaker 16 to the listener 12 is d1 and the distance from the second speaker 18 to the listener 12 is d2, d1 <d2 always holds. The first position when the position of the listener 12 moves from the point P to the point P '
Assuming that the distance from the speaker 16 to the listener 12 is d1 'and the distance from the second speaker 18 to the listener 12 is d2', the change amount d1'- The magnitude relation of d1, d2'-d2 is d
1'-d1>d2'-d2. Therefore, when sound is emitted from the speakers 16 and 18, the attenuation characteristic of the sound pressure level due to the horizontal distance from the wall surface 14 is as shown in FIG. As shown, the second speaker 1
The attenuation characteristic of the sound emanating from 8 is gentle as shown by the dashed line. Therefore, the first and second speakers 16, 1
The attenuation characteristic when the same sound is emitted from No. 8 is an intermediate characteristic between the two as shown by the dotted line.

At this time, the first and second speakers 16, 1
If sound is emitted simultaneously from the speakers 8, the sound image is localized upward (between the first and second speakers 16 and 18), so that the audio signal supplied to the second speaker 18 is supplied to the first speaker 16. The audio signal is delayed for a predetermined time such that no echo is generated, for example, about 10 msec. As a result, the Haas effect is obtained, and the sound image is transmitted to the first speaker 16.
Localize in the direction of. Further, the sound emitted from the second speaker 18 can be increased by an amount such that the sound image localization effect does not occur with respect to the sound emitted from the first speaker 16, for example, about +6 dB. Thereby, the sound image is still localized in the direction of the first speaker 16. Thus, the first
The sound emitted from the sound source can be reproduced by imitating the attenuation characteristics of the sound emitted from the sound source located at a position deeper than the speaker 16.

Next, a case where a video conference system is configured by utilizing the present invention will be described. Here, FIG.
As shown in the plan view, the rooms 20 and 22 at the two separated points A and B are apparently connected to one room, and the attendees 24 (24-1, 24-2,.
..) And 26 (26-1, 26-2,...) Will be described. The length of the room is room 20,
It is assumed that a total of about 8 meters is set to about 8 m, and a meeting is performed without using a PA (loudspeaker).

A case where a voice spoken in the room 20 is reproduced in the room 22 will be described. The same is true for the opposite case. When the rooms 20 and 22 are one connected room, the rooms 20 and 22 when the attendee (speaker) talks in the room 20
The change in the sound pressure level (attenuation characteristic) in FIG. This characteristic C is attenuated according to the inverse square law, and the attenuation in the room 22 becomes gentle. On the other hand, a speaker that reproduces the speaker's voice in the room 22 (a speaker arranged facing the attendee (listener)) is installed near the boundary 28 between the room 22 and the room 20. Therefore, the sound pressure level of the voice reproduced from the speaker sharply attenuates as shown by the characteristic D in FIG. Therefore, it is not possible to reproduce the attenuation characteristics of the voice uttered in the room 20 with only the speakers arranged facing the listener (to be precise, arranged substantially horizontally in front of the listener's head). .

Therefore, by reproducing both the speaker arranged in the room 22 facing the listener and the speaker arranged above the speaker, the characteristic approximate to the attenuation characteristic of the voice emitted from the room 22 is obtained. To be obtained.

In order to obtain an approximate characteristic, first, a target characteristic of the attenuation characteristic is set. 1m-4 from the boundary 28 in the room 20
It is assumed that the speaker's voice in the range of m is reproduced. The attenuation characteristics from the sound source at a position 1 m from the boundary 28 in the room 20 are shown in FIG.
It becomes like the characteristic E of. The attenuation characteristic from the sound source at a position 4 m from the boundary 28 in the room 20 is as shown by the characteristic F in FIG. Even if the attenuation characteristics from the sound source in the room 20 are approximated by speakers arranged above and below the boundary 28 in the room 22, if the attenuation characteristics within 1 m from the boundary 28 in the room 22 are steep, Since it is inevitable and it is difficult to approximate the attenuation characteristic, this range is excluded from the control target, and the listener in the room 22 does not enter or does not enter this range. At this time, characteristics E,
In F, the sound pressure level is stored between the boundaries 28 and 28 'for convenience. That is, in the room 22, the actual boundary 2
A position 8 m to 1 m before is assumed to be a temporary boundary 28 '. The target characteristic in the room 22 is set to a characteristic G intermediate between the characteristics E and F. The applicable range of the target characteristic G is the boundary 28
From 1 m to 4 m.

The attenuation characteristic reproduced in the room 22 is also affected by the height of the microphone in the room 20. The characteristic H in FIG. 7 indicates that the microphone 36 is arranged in the room 20 at the position of the boundary 28 facing the speaker (to be precise, at the position of the boundary 28 corresponding to the height of the mouth in front of the speaker). Shows the change in the microphone input sound pressure level due to the distance from the boundary 28 when the microphone is placed, and the characteristic I shows the change in the microphone input sound pressure level due to the distance from the boundary 28 when the microphone is arranged above the microphone. Regarding these characteristics H and I, the same can be said for FIG. 2 showing the arrangement of the speakers.
That is, the distance from the microphone facing the speaker to the speaker is always shorter than the distance from the microphone above to the speaker, and the distance between the microphone and the speaker when the speaker moves in the front-back direction with respect to the boundary 28. The amount of change in the distance is greater for the microphone facing the speaker than for the microphone above. As a result, the input sound pressure level characteristic H of the microphone facing the speaker becomes steeper, whereas the input sound pressure level characteristic I of the upper microphone becomes gentle.

FIG. 8 shows a microphone facing the speaker,
The reproduction characteristics in the room 22 when the voice speaking at the positions 1 m and 4 m from the boundary 28 are collected are shown in comparison with the ideal characteristics (characteristics E and F in FIG. 6). The figure shows a case where the playback volume in the room 22 is adjusted so that the voice spoken at a position 1 m from the boundary 28 in the room 20 is accurately reproduced in the room 22. At this time, it is 4
The playback volume of the voice spoken at the position of m becomes very low.

FIG. 9 shows the reproduction characteristics when sound is picked up by the microphone located above the boundary 28. The figure shows a case where the playback volume in the room 22 is adjusted so that the voice spoken at a position 1 m from the boundary 28 in the room 20 is accurately reproduced in the room 22. At this time, the decrease in the reproduction volume of the voice speaking at a position 4 m from the boundary 28 in the room 20 is alleviated as compared with the case where the microphone is arranged facing the speaker (FIG. 8), and The corresponding natural volume feeling is reproduced. Therefore, the microphone arrangement is better than the position facing the speaker.
By arranging it above, the volume level of the voice spoken at each position in the room 20 can be reproduced more accurately. However, this is a story from the viewpoint of reproducing the sound volume level, and the second speaker 18 arranged above reproduces the sound at a higher volume. You should also consider that you can't get too close.

The configuration of a video conference system using the present invention will be described. FIG. 1 shows an arrangement in a room at one point where a video conference is held. The room 22 is composed of, for example, one room in a building, and has a length of about several meters. A panel 32 is provided in front of a wall surface 30 in front of the room 22, and a sound absorbing material 34 such as glass wool is filled in the opening portion thereof with a thickness of 30 cm or more. So that they are not reflected by the sound. On the front surface of the sound absorbing material 34, the first speaker 16 is provided at a height position facing the attendee 26, that is, at a position which is substantially at the height of the head of the attendee 26 and is horizontally separated from the head.
In the horizontal direction. Almost right above the first speaker 16, the second speaker 18 is arranged in front of the sound absorbing material 34 in the direction of the attendees 26 and horizontally. It is desirable that the installation height of the second speaker 18 be 120 cm or more from the first speaker 16.

A microphone 36 is disposed almost directly above the first speaker 16 and slightly below the second speaker 18 in front of the sound absorbing material 34. The microphone 36 is unidirectional or bidirectional (property having directivity forward and backward) in order to prevent howling or echo caused by picking up direct sound from the first speaker 16 and the second speaker 18. The directivity is arranged horizontally in the direction of the attendee 26. On the front surface of the panel 32, a sound-transmissive screen 38 having fine holes formed at intervals of several millimeters
(Same screens used in cinemas). Since the area within 1 m from the screen 38 is out of control, the attendee 26 is kept out.
It should be noted that by disposing the screen 38 at a distance of about 1 m from the panel 32, it is possible to prevent the screen 38 from actually entering. On the ceiling of the room 22, there is a video projector 4
0 is arranged, and the image projected from the video projector 40 is projected on the screen 38.

FIG. 10 shows the arrangement of the screen 38 as viewed from the front. The combination of the first and second speakers 16, 18 and the microphone 36 is vertically arranged as an example.
Further, four such combinations are provided at equal intervals in the horizontal direction (for example, at intervals of about 60 cm). The speakers 16 and 18 are all the same. The microphones 36 are all the same. The speakers 16 and 18 and the microphone 36 of each set are all arranged on the same plane behind a screen 38. When the screen 38 is relatively small, the speaker 18 and the microphone 36 can be arranged above the screen 38 instead of behind the screen 38. At the same height position as the first speaker 16 at the center in the width direction of the screen 38, a television camera 42 is arranged with its lens 42a oriented horizontally in the direction of the attendees 26. A window (opening) 44 is formed at the position of the television camera 42 on the screen 38, and the television camera 4
A second lens 42 a faces the room 22 through the window 44.

FIG. 1 shows a system configuration for conducting a video conference between rooms having the configuration shown in FIG. 1 at separated points A and B.
It is shown in FIG. The signal processing device 46,
A video signal and an audio signal are bidirectionally communicated via a transmission path 50 such as a network, the Internet, or a telephone line. Speakers 16 and 1 at points A and B
8 and microphones 36 are provided, each of which is a set of four sets, which face each other (that is, the room 20).
The combination G-1 of the leftmost pair as viewed from the attendee 24 and the rightmost pair as viewed from the attendee 26 in the room 22, the second pair from the left of the room 20, and the second pair from the right of the room 22 G-2, the third set from the left of the room 20 and the third set from the right of the room G-3, the rightmost set of the room 20 and the leftmost set of the room 22 Are combined with each other.

FIG. 12 shows the configuration of the signal processing devices 46 and 48 relating to the audio signal processing for one combination G-1 of points A and B. In the signal processing device 46 at the point A, the collected sound signal of the microphone 36 is output via the microphone amplifier 52 and the mixer 54 and
0 is input to the signal processing device 48 at the point B. The signal processing device 48 appropriately corrects the frequency characteristics of the input audio signal by the equalizer 56, amplifies it by the power amplifier 58, and reproduces it from the first speaker 16. The signal processing device 48 converts the input audio signal into an equalizer and a delay circuit 60 so that the reproduction frequency characteristics of the first and second speakers 16 and 18 are substantially equal at the position of the listener and the second speaker 1
The frequency and level are adjusted so that the sound pressure of the sound emitted from the speaker 8 is higher than the sound pressure of the sound emitted from the first speaker 16 by about +6 dB, and output with a delay of about 10 msec. This audio signal is amplified by the power amplifier 62 and output from the second speaker 18.

The sound pickup signal of the microphone 36 at the point B is output via the microphone amplifier 64 and the mixer 66 and is input to the signal processing device 46 at the point A via the transmission path 50. The signal processing device 46 appropriately corrects the frequency characteristics of the input audio signal by the equalizer 68, amplifies the input audio signal by the power amplifier 70, and reproduces the audio signal from the first speaker 16. In the signal processing device 46, the input audio signal is transmitted from the second speaker 18 by the equalizer and the delay circuit 72 so that the reproduction frequency characteristics of the first and second speakers 16 and 18 are substantially equal at the listener's position. The frequency and level are adjusted so that the sound pressure of the sound is higher than the sound pressure of the sound emitted from the first speaker 16 by about +6 dB, and the sound is output with a delay of about 10 msec. This audio signal is amplified by the power amplifier 74 and output from the second speaker 18.

If the delay time given to the sound reproduced from the second speaker 18 is too short, the first speaker 1
Due to the interference with the sound reproduced from No. 6, the comb filter characteristic becomes strong and the sound becomes hazy. If the sound is too long (for example, 15 msec or more), the sound is heard separately (it becomes an echo), so about 10 msec is appropriate. . Also, the second
If the gain given to the sound reproduced from the speaker 18 is too large (for example, +8 dB or more), the sound image of the reproduced sound is localized above the direction of the first speaker 16,
If it is too small, the effect of improving the attenuation characteristics cannot be obtained, so that around +6 dB is appropriate.

The echo cancellers 76 and 78 receive the direct sound reproduced from the first speaker 16 and the second speaker 18 of one room 20 by the microphone 36 of the room 20 and the first sound of the other room 22. Speaker 16 and the second
Of the room 2
The sound is picked up by the second microphone 36 and the first
Is reproduced from the speaker 16 and the second speaker 18, and howling caused by repetition of the reproduction is prevented. That is, the echo canceller 76 converts the audio signal (input signal to the equalizers 68 and 72) reproduced by the speakers in the own room 20 into the equalizer 68,
Transfer characteristics of a system from the system of the power amplifier 70 and the first speaker 16 and the system of the equalizer 72, the power amplifier 74, and the second speaker 18 in parallel with the system to the microphone 36 and the microphone amplifier 52 via the space ( Impulse response) is convolved with the response waveform, and the convolved output is input to the mixer 54 to perform necessary level adjustment and the like, and then subtracted from the sound pickup signal of the microphone 36 of the own room 20 to obtain the same signal. In 20, an audio signal component corresponding to a direct sound reproduced by the first speaker 16 and the speaker 18 and collected by the microphone 36 is canceled.

Similarly, the echo canceller 78 is provided in the own room 22.
Audio signals reproduced by the first speaker 16 and the second speaker 18 (input signals to the equalizers 56 and 60)
From the system of the equalizer 56, the power amplifier 58, the first speaker 16 and the system of the equalizer 60, the power amplifier 62, and the second speaker 18 in parallel with the system, the microphone 36 and the microphone amplifier 64 are passed through the space. A response waveform equivalent to the transfer characteristic (impulse response) of the system is convolved. The convolved output is input to a mixer 66 to perform necessary level adjustments, etc., and then subtracted from a signal collected by the microphone 36 in the own room 22. As a result, the microphone 3 is reproduced by the first speaker 16 and the second speaker 18 in the own room 22.
The sound signal component corresponding to the direct sound collected in step 6 is canceled.

Other combinations G-2 and G- between points A and B
3 and G-4 are configured in exactly the same manner as in FIG. The signal processing devices 46 and 48 at the points A and B are:
For the video signal, the TV camera 42 at one point A
Is transmitted to the other point B via the transmission path 50 and the video projector 4 at the other point B
0 to the screen 38 at the other point B, the video signal captured by the television camera 42 at the other point B is transmitted to one point A via the transmission path 50, Signal processing is performed so as to project from the video projector 40 to the screen 38 at the one point A.

FIG. 13 shows the attenuation characteristics of the reproduced sounds in the rooms 20 and 22 according to the arrangement in the room in FIG. 1 and the system configuration in FIG. 12, according to which the target characteristics G in FIG. An attenuation characteristic is obtained, and a sense of depth is obtained. Also,
The combinations of the speakers 16 and 18 and the microphone 36 are arranged in the horizontal direction, and the combinations facing each other in the rooms 20 and 22 are combined (combinations G-1, G-2, G-3, and G in FIG. 11).
-4), since the transmission system of FIG. 12 is independently configured to collect and reproduce the audio signal, the two systems can be connected according to the positional relationship between the speaker in one room and the listener in the other room. Sound from the direction connected by a straight line first reaches the listener's ear. As a result, a sense of localization in the direction of the speaker can be obtained for each listener by the preceding sound effect in the left-right direction. As described above, a sense of unity between sound and video can be obtained, and a sense of reality in a meeting without using PA can be reproduced.

In the above-described embodiment, the case where the present invention is applied to a conference between two points A and B has been described. The present invention can be applied to A and B, B and C, and C and A), respectively.

[Brief description of the drawings]

FIG. 1 is a side view and a plan view showing an arrangement in a room used for a video conference system using the present invention.

FIG. 2 is a side view showing a speaker arrangement example of the audio reproducing apparatus of the present invention.

FIG. 3 is a diagram showing attenuation characteristics of sound emitted from each speaker of FIG. 1;

FIG. 4 is a plan view showing the concept of a room reproduced in a video conference system using the present invention.

FIG. 5 is a diagram showing attenuation characteristics of a voice spoken in one room of FIG. 4 and attenuation characteristics of a voice reproduced from a speaker in the other room.

FIG. 6 is an explanatory diagram of target characteristics of attenuation characteristics reproduced in each room.

FIG. 7 is a characteristic diagram showing a change in a sound pressure level of a collected sound signal depending on a height at which a microphone is installed.

FIG. 8 is a diagram illustrating a difference in attenuation characteristics of a sound reproduced from a speaker due to a difference in distance between the microphone and the speaker when the microphone is arranged at a position facing the speaker.

FIG. 9 is a diagram illustrating a difference in attenuating characteristics of a speaker-reproduced sound due to a difference in distance between the microphone and the speaker when the microphone is arranged at an obliquely upper position in front of the speaker.

FIG. 10 is a front view of a screen in the room arrangement of FIG. 1;

11 is a diagram showing a system configuration for holding a video conference between rooms having the configuration shown in FIG. 1 at points A and B separated from each other.

12 is a block diagram showing a configuration inside the signal processing devices 46 and 48 of FIG. 11 for one combination of points A and B.

13 is a diagram showing attenuation characteristics of reproduced sound in each room according to the system configuration of FIG. 12;

[Explanation of symbols]

 12 Listener 16 First Speaker 18 Second Speaker 20,22 Room 24,26 Attendee 36 Microphone 38 Sound-Transmissive Screen 40 Video Projector 42 Television Camera 42a Television Camera Lens 44 Window 46,48 Signal Processing Device 50 Transmission path

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-330092 (JP, A) JP-A-61-237600 (JP, A) JP-A-8-125760 (JP, A) JP2645731 (JP, A) B2) J. Brawelt, Masayuki Morimoto, Toshiyuki Goto, Spatial Acoustics, Japan, Kashima Press, July 1986, 58-68, 142-154 (58) Fields investigated (Int. Cl. ⁷ , DB name) H04R 3/00 310

Claims (7)

(57) [Claims] A first speaker disposed substantially facing the listener; a second speaker disposed substantially above the first speaker and obliquely above the listener; A signal processing device for supplying an audio signal to a speaker and reproducing the same, and supplying a signal delayed from the audio signal in a time range in which no echo is generated to the second speaker to reproduce the audio signal; . 2. The signal processing device according to claim 1, wherein the output sound pressure level of the audio signal reproduced from the second speaker is set within a range in which a sound image based on the audio signal is not localized in the direction of the second speaker. 2. The audio reproducing apparatus according to claim 1, wherein the audio signal is reproduced at a level higher than the output sound pressure level of the audio signal reproduced from the first speaker. 3. An apparatus for holding a conference between two points separated from each other, comprising: a first speaker disposed substantially facing an attendant at each of said points; and a first speaker disposed above said first speaker. A second speaker arranged diagonally above the attendee, a microphone arranged at an appropriate position, and an audio signal supplied to and reproduced from the first speaker, and the audio signal is not echoed. A signal processing device for supplying a signal delayed in a time range to the second speaker and reproducing the signal is disposed, and an audio signal collected by the microphone at one point is transmitted via a transmission path to the signal at the other point. The sound signal collected by the microphone at the other point is transmitted to the processing device and reproduced by generating a time difference due to the delay from the first and second speakers at the other point. At the point And transmit to the processor the first one point said, made by play caused a time lag due to the delay from the second speaker communication conference device. 4. The communication conference apparatus according to claim 3, wherein the microphone is disposed substantially above the first speaker and at a position not overlapping the second speaker. 5. A combination of the first and second speakers and the microphone at each of the points is disposed at substantially the same position in the left-right direction of a wall surface in the room, and the first and second speakers and the microphone are combined. A plurality of microphone combinations are arranged at appropriate intervals in the left-right direction of the wall surface, and the signal processing devices at the two points combine the facing pairs at the two points, respectively, and 5. The communication conference apparatus according to claim 3, wherein the collected audio signal is transmitted and reproduced. 6. The sound-absorbing wall according to claim 3, wherein the first and second speakers and the microphone are arranged on a sound-absorbing wall formed by arranging a sound-absorbing material on a wall in a room. A communication conference device according to claim 1. 7. A television camera disposed at each of the points substantially facing the attendee; and a lens position of the television camera disposed at least over the first speaker and a front surface of the television camera. A sound-transmissive screen having a window formed therein, and a video projector for projecting an image on the screen are respectively arranged, and the signal processing device at each of the points converts a video signal captured by the television camera at one of the points. The video signal at the other point is transmitted from the video projector at the other point to the screen at the other point via the transmission path, and the video signal captured by the television camera at the other point is transmitted through the transmission path. Via the video projector at the one point to the screen at the one point. 7. The communication conference device according to any one of items 3 to 6.