JPH03141799A - Loudspeaker system - Google Patents

Abstract

PURPOSE:To obtain a loundspeaker appropriate for conferences by arranging one or more microphones in each zone divided set up in each position when plural persons are to hold a conference or the like in the same space area, distributing a collected voice signal to the zones and generating the loundened voice from speakers arranged in respective zones. CONSTITUTION:A voice signal outputted from each zone is supplied to the mixers 4 (4B to 4E) of zones other than the self-zone. Namely when the voice of a speaker in the zone A e.g. is supplied from the mixers 4B to 4E in the zones B to E, the loudened voice is generated from the speakes SB to SE. On the other hand, attendants in the zone A can listen the contents of the speaker in the zone A by his natural voice. Since voices collected by the microphone M in the zones other than the self-zone is outputted from each speaker, a sufficiently large howling margin (high safety loud-speaking gain) can be obtained. since a signal processing part 2 is provided with an expanding processing circuit and a compressing processing circuit, level conversion processing can also be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a public address system suitable for when a plurality of people discuss or hold a conference in the same spatial area.

[Summary of the Invention] The public address system of the present invention divides the inside of a conference room or the like into a plurality of zones and sets one or more microphones (hereinafter referred to as (simply referred to as a microphone). Then, the audio signals collected by the microphone in each zone or mixed and output are:
The signal is supplied to the speaker means corresponding to all zones other than that zone, so that the sound is amplified and output.

Further, by providing an expanding means and a compressing means at the output stage of the audio signal from the microphone means in each zone, the degree of amplification is changed according to the level of the collected sound, and furthermore, by providing a delay means, , the sound image can be displayed at an appropriate position regardless of the installation position of the speaker means.

[Prior Art] In meetings held in large conference halls with a relatively large number of people, multiple microphones are usually placed on the desks of each participant, and the participants' comments are transmitted through mixers, speakers, etc. into the conference hall. The sound is being amplified.

By the way, when holding an important meeting, in order to maintain the confidentiality of the content of the meeting, when using such a public address system, it is desirable to not have an operator intervene to operate it. There is. Further, it is desirable that the speaker does not have to turn on/off his or her own microphone. For this reason, normally a predetermined number of microphones assigned to each participant are all turned on, so that no matter who speaks, all the microphones are amplified and output without any operation.

However, since microphones also pick up room noise, the more microphones there are, the higher the noise level will be, and the clarity of the amplified voice will be greatly impaired.

To solve this problem, public address systems have been developed that automatically turn on only the microphone of the person currently speaking and turn off all other microphones, allowing clear and clear voice without any operation. A public address system that does not impair sound quality has been realized.

[Problems to be Solved by the Invention] However, such a public address system that automatically turns on only the microphones corresponding to the speakers has the following problems.

In order to automatically control only the speaker's microphone to be turned on, for example, there is a method of detecting that the level of the voice input from the front direction of the microphone is higher than a predetermined level than the voice from other surrounding directions. However, in any case, since the microphone is turned on after a speech is made and a voice of a predetermined level or higher is input, a problem arises in that the beginning of the speech is cut off and the content of the speech becomes difficult to hear.

Also, if someone else interrupts and speaks while you are speaking,
When the speaker's voice is low, the content of the speech may be cut off midway, which is a problem.

Furthermore, in any of the conventional systems, there is a strong demand for a public address system with excellent howling margin so as to eliminate the need for loudspeaker gain adjustment in multiple amplifiers due to the desire to avoid operator intervention.

[Means for Solving the Problems] The present invention has been made in view of the above points, and one or more microphones are installed in each zone that is divided and set for each location. The collected and output audio signal is supplied to speaker means corresponding to all zones other than the zone where the audio signal was output, and is amplified and output.

Furthermore, expanding means and compressing means are provided at the output stage of the audio signal from the microphone means of each zone, and when the audio signal is below a set first level, expansion processing is performed and the audio signal is If the level is higher than the second level set higher than the second level, the amplification degree is changed in accordance with the level of the collected sound by performing compression processing and outputting the sound.

Furthermore, by providing a delay means at the output stage of the audio signals from the microphone group, the sound image can be displayed at an appropriate position regardless of the installation position of the speaker means.

[Function] Since the sound picked up by the microphone means in each zone is not supplied to the speaker means of that zone, it is possible to amplify the sound with a margin for howling. Noisy voices are hardly amplified, and loud voices above a predetermined level are lowered in degree of amplification to obtain amplified voices that are easy to hear. Further, the delay means utilizes the Haas effect to localize the sound image in the direction of the speaker.

[Example] Figures 1 and 2 show an example of the public address system of the present invention, and Figure 1 is an explanatory diagram of a conference hall divided into five zones by location. , FIG. 2 is a system block diagram corresponding to the zone division of FIG. 1.

As shown in Fig. 1, it is assumed that tables T are arranged in a rectangular manner in a conference hall R and a conference is held with 28 people, and one microphone M is assigned to each attendee. shall be. Note that P indicates the position of the chair.

In such a conference hall R, if it is divided into zones A to E as shown in the figure, each zone has a microphone MA.
I-MA4, lVi B 1 to lVi B6, M (1
-M c6M , , ~M , , MEI'-'-M
E6 will be assigned. And the speaker is
For example, SA to S are provided above (ceiling) at each zone position corresponding to each zone. Note that all microphones M are always on.

When setting up a conference hall like this, the public address system is
It is configured as shown in the figure.

In FIG. 2, the constituent parts corresponding to each zone are shown within the dashed lines, and the symbols (A-E) indicating the zone are added to the symbols (1 to 5) of each block.

1 is a microphone mixer that mixes and outputs the sounds picked up from the microphones M in the zone; for example, the microphone mixer IA picks up the signal from the microphone M AI-M A 4 as a signal from zone A and outputs it. do.

Reference numeral 2 denotes a signal processing unit that performs compression processing and expansion processing on the audio signal output from the microphone mixer IA, and its detailed operation will be described later.

3 is a delay circuit, for example, 10 to 2
A predetermined delay time of about 0m5ec is added and output. The function of this delay circuit 3 will be described later.

4 is a mixer for the audio signal supplied to be output from the speaker S corresponding to the zone, and 5 is a power amplifier.

As can be understood from this figure, the audio signals output from each zone are each supplied to the mixer 4 of the zone other than its own zone. Therefore, for example, the voice of a speaker in zone A is transmitted from zone B. It is supplied to mixers 4B to 4E up to E zone, and is amplified and output from speakers 5ll-3E, but is not output from speaker SA in A zone. Just as you will hear what is being said in your own voice, each speaker will output the sound picked up by the microphone M in a zone other than its own, so there is sufficient feedback margin (high safety amplification gain). ) can be obtained.

Furthermore, in this embodiment, due to the action of the signal processing section 2,
Even if all the microphones M are on, the noise level in the conference hall R will not increase, and even if relatively loud audio is input, it will not be amplified and become difficult to hear. do not have.

That is, since the signal processing section 2 is equipped with an expansion processing circuit and a compression processing circuit, it is possible to perform level conversion processing on the input audio signal as shown by the dotted line in FIG. 3 and output it. (The solid line indicates the case where level conversion processing is not performed).

As shown in FIG. 3, when the level of the input signal to the signal processing unit 2 is Ll or less, expansion processing is performed to suppress the level of minute audio components such as noise. Further, when the level of the human input signal is equal to or higher than L2, compression processing is performed, so that the loud signal is compressed and is supplied to the power amplifier 4 and the speaker S as a signal with a moderate volume.

By doing this, a large number of microphones M are installed,
Even if all the microphones M are always on, the noise voice is hardly amplified, so that the contents of the speech can be heard with very good clarity. Furthermore, there is no problem even if microphone M is always on, so
This eliminates the need for devices and circuits that automatically turn the microphone on and off, simplifying the system configuration, and
Problems such as cutting off the beginning of what is being said and interruptions are completely eliminated.

Note that it is desirable that L2, which is the threshold level for expansion and compression processing, can be set in consideration of the size of the conference hall, the number of microphones, the noise condition, and the like.

Furthermore, in this embodiment, as described above, the audio signal obtained in each zone is delayed by a predetermined time in the delay circuit 3 before being supplied to zones other than that zone, thereby changing the sound image to the speaker. It can be localized in the direction of

As known as the Haas effect (first wavefront law), human hearing senses a sound image in the direction of the source of the first sound wave that arrives.

For example, as shown in FIG. 4(a), speakers SL and SR
is arranged and each speaker outputs, for example, a telephone ring tone. When the sound is heard at point X, the arrival times tL and tR of the output sound from each speaker are the same, so
The user will feel the sound image as if the telephone is present at the SP point and the ringing tone is being emitted from there. However, if only the speakers S and L are moved to the rear as shown in Figure 4(b), and the arrival time of the output sound is t L < t R, the person at point A sound image is obtained in the direction, ie, the installation point of the speaker SL, so that the telephone appears to be at the point SP°.

This effect differs depending on the level difference and time difference of each sound wave that arrives with a time difference, but roughly speaking, it is the fifth sound wave.
This can be obtained if the condition of being within the shaded area shown in the figure is satisfied.

For example, when there are first and second sound waves that arrive at different times, even if there is a level difference of about 1 odB (the first sound wave is at a lower level), the time required for the second sound wave to arrive is If the time difference is about 10 to 20 m5ec, a sound image will be felt in the direction of the first sound wave.

Therefore, by giving an appropriate delay time by the delay circuit 3,
By making the speaker's real voice first reach the attendees of the meeting and then the audio output from the speaker S, each attendee can be made to feel a sound image in the speaker's direction. Furthermore, the speaker allows clear audio to be heard. For this reason, even if the speaker S is placed on the ceiling6, the sound will feel like it is coming from the speaker's direction rather than from the ceiling, and the speaker's position (visual position) and sound image position ( Since the hearing positions (hearing positions) are matched, attendees can proceed with the meeting in a very natural environment without worrying about the presence of public address equipment.

If the conference is held in a larger venue, the arrival time of the real voice may be delayed depending on the zone, so consider the distance between each zone and set the delay time of the audio signal supplied to each zone to be different. It may be possible to do so.

As described above, the public address system of this embodiment does not require operator operation during a conference, provides a margin for howling, does not increase noise level, and does not impair clarity. Additionally, the use of a public address system does not impair the natural conference environment.

In this embodiment, one microphone M is provided for each attendee, but one microphone M may be provided for two attendees, or one microphone M may be provided for each zone.

FIG. 6 shows another embodiment of the present invention, and shows a system generally known as a video conference, which allows a conference to be held between remote locations by using, for example, a public telephone line. It is. In addition, in video conferencing,
Although the video signal is transmitted at the same time, the video signal system is not directly related to the present invention, so it is omitted, and only the audio system is shown.

In this figure, the first conference hall R1 is divided into A zone and C zone, and the second conference hall R1 is divided into D zone and E zone.
A public telephone line PT connects conference hall R2 in zone F and third conference hall R3 in zone F. 6 is conference hall R1, R
2 is a mixer for mixing the audio signals obtained from each zone and outputting the mixture to the public line PT; 7 is a mixer for outputting the mixture to the public line PT;
It is a transmitting/receiving terminal for T.

By configuring the system in this way, the present invention can also be used for video conferences, and the same effects as the above-described embodiments can be obtained in each conference hall. Note that there is no need to provide a delay time to the audio signal output to the external public line using the delay circuit 3).

The above embodiments have been exemplified by using the loudspeaker system of the present invention in conferences, but it goes without saying that it can also be applied to other purposes other than conferences.

[Effects of the Invention] As explained above, the public address system of the present invention does not require a system operator while in use, has an improved margin for howling, does not impair the clarity of the amplified voice, and is easy to use. This system configuration has the advantage that problems such as interruptions in amplified audio due to microphone switching operations do not occur. Furthermore, by using an appropriate delay operation, the sound image can be localized in the direction of the speaker, which can produce many excellent effects, such as making it possible to prevent the user from sensing the presence of the loudspeaker equipment. Therefore, it is very useful for use in meetings and the like.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of zone division in one embodiment of the present invention, FIG. 2 is a system block diagram of one embodiment of the present invention, FIG. 3 is an explanatory diagram of the operation of the signal processing section, and FIG. )(b)
5 is an explanatory diagram of the sound image position, FIG. 5 is an explanatory diagram showing the relationship between level difference and delay time for obtaining the Haas effect, and FIG. 6 is a system block diagram of another embodiment of the present invention. LA-IF is a microphone mixer, 2A to 2F are signal processing units, 3A to 3E are delay circuits, 4A to 4E are mixers, 5A
~5E represents a power amplifier, SA~S represents a speaker, and M represents a microphone. Diagram

Claims (3)

[Claims] (1) 1 or 2 for each zone divided and set by location
The above microphones are installed, and each audio signal collected in each zone is distributed to a zone other than the zone where the audio signal was collected, and the sound is amplified by the speaker means installed in the zone. A public address system characterized by: (2) Expanding means and compressing means are provided after the mixer output end of one or more microphones installed in each zone, and the audio signal picked up by the microphone is If the audio signal is below the first level, the audio signal is expanded, and if the audio signal is above the second level, which is set higher than the first level, the audio signal is compressed and output. A public address system according to claim (1), characterized in that: (3) A delay means is provided after the mixer output end of the one or more microphones installed in each zone, and the audio signal picked up by the microphone is transmitted to the zone in which the microphone is installed. The public address system according to claim 1, wherein the loudspeaker means corresponding to other zones are supplied with a predetermined time delay.