JP2006211178A - Loudspeaker system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a loudspeaker system capable of loudspeaking with high quality by hands-free. <P>SOLUTION: A plurality of microphones 1 with directivity limited therein and a plurality of speakers 6 with the directiveity limited therein are arranged by distribution on the ceiling of a conference room, A sound source position detector 2 compares input signal levels from the microphones 1, and detects the microphone in the neighborhood of a speaker as a sound source position. A speaker face direction detector 3 detects the direction of the face of the speaker, based on the frequency characteristic patterns of input signals in the microphones 1. The input signals from the microphone which is defined as the sound source position by the sound source position detector 2 are selected by an input changeover part 4 and input to a speaker output adjuster 5. A delay time, an output level, and a frequency characteristic are set in response to positions with respect to the signals to be output to the respective speakers 6, so as to be output to each speaker 6. Consequently, listening is performed with uniform sound quality at any position of the room. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a loudspeaker system, and is particularly suitable when applied to a small and medium conference room.

If the speaker and audience are in the same room, and the venue is larger than a certain size and the voice content of the speaker cannot be sufficiently heard by the real voice alone, the loudspeaker is required.
When performing loudspeaking, a fixed microphone is usually installed in order to pick up clear sound, and it is necessary for the speaker to speak at that position, or for the speaker to carry the microphone. Met. Even when the speaker changes, such as during a question-and-answer session, the questioner needs to move to the position of the fixed microphone or move the microphone.
In reproduction systems, loudspeakers that are concentrated or distributed on the ceiling are often used. There was no uniform loudness in the room.
Furthermore, due to the risk of howling, it was difficult to speak multiple lines.

In Patent Document 1, in a system in which the sound collected by a fixed microphone is amplified using speakers distributed on the ceiling, the volume of the speaker is set to decrease as it approaches the microphone, and A temple acoustic system is described in which the synthesized sound volume with the loud sound of a speaker is averaged.
Patent Document 2 describes an invention relating to a method and apparatus for recognizing a speaker's face.
JP-A-9-65470 Japanese Patent Laid-Open No. 10-243494

As described above, in the conventional loudspeaker system, it is necessary for the speaker to move to the position of the fixed microphone, or to move the microphone to the position of the speaker.
In addition, it has been proposed to control the volume of the loud sound output from the speakers arranged in a distributed manner to equalize the synthesized sound volume of the real voice and the loud sound, but consideration is given to the propagation delay time of the acoustic signal. It wasn't.
Therefore, an object of the present invention is to provide a loudspeaker system that can perform hands-free and high-quality loudspeaker without having to move to the position of the microphone or move the microphone.

In order to achieve the above object, a loudspeaker system according to the present invention includes a plurality of microphones distributed on a ceiling, each microphone having a plurality of microphones having limited directivities, and a plurality of microphones distributed on the ceiling. A plurality of speakers, each speaker having a limited directivity, sound source position detecting means for detecting a sound source position based on input signals from the plurality of microphones, and a plurality of speakers from the plurality of microphones Speaker face direction detection means for detecting the face direction of the speaker based on the input signal, and a signal input from the microphone determined to be a sound source position by the sound source position detection means between the microphone and each speaker. And adjusting the gain, delay time, and frequency characteristics according to the distance and the face direction detected by the speaker face direction detecting means, And outputs the serial plurality of speakers are those having a speaker output adjustment means.
The speaker output adjusting means can output input signals from a plurality of microphones to the plurality of speakers.

According to the loudspeaker system of the present invention, the sound source position (speaker position) is detected by a plurality of microphones distributed on the ceiling, and the sound is picked up by the microphones at the sound source position. There is no need to carry a microphone.
A plurality of speakers arranged in a distributed manner on the ceiling by adjusting the level, delay time, and frequency characteristics of the input signal from the microphone corresponding to the sound source position according to the distance from the microphone and the direction of the speaker's face Therefore, natural and uniform loudspeaking is possible in the same room.
Furthermore, when a new sound source position is detected, the microphone is switched, and the output level, delay time, and frequency characteristics of the signal amplified from each speaker are also changed accordingly. Uniform loudspeaking is possible.
Furthermore, due to the restrictions on the directivity of the microphone and the speaker, it is possible to perform sound amplification in a plurality of systems simultaneously in the same room.

FIG. 1 is a block diagram showing the overall configuration of the loudspeaker system of the present invention. This loudspeaker system is suitable for a small and medium-sized conference room where all listeners cannot sufficiently hear only by the speaker's real voice.
In this figure, 1 is a plurality (m) of microphones distributed on the ceiling of a room equipped with the loudspeaker system of the present invention, and 6 is a plurality (n) of speakers similarly distributed on the ceiling. Here, each microphone 1 (MIC1 to MICm) has directivity limited so as to pick up only sound in the neighboring area, and m microphones distributed on the ceiling are used in the entire room. It is made to cover. Similarly, each speaker 6 (SP1 to SPn) has a directivity limited so as to be amplified only in the vicinity of each area, and the entire room is covered with n speakers distributed on the ceiling. Has been made to be able to. The arrangement intervals of the plurality of microphones and the arrangement intervals of the plurality of speakers are determined according to the directivity and the ceiling height. However, it is desirable to arrange the microphone and the speaker so that the distance between them is as far as possible.
Moreover, a planar speaker may be used for the plurality of speakers 6, and the speaker may be used as a part of the system ceiling.

  2 detects the position of the speaker by monitoring the level of the input signal from each microphone (MIC1 to MICm) of the plurality of microphones 1 and outputs a control signal to the input switching unit 4 and the speaker output adjusting unit 5. The output sound source position detection unit 3 detects the speaker's face direction from the signal level of each input signal from each microphone of the plurality of microphones 1 and outputs a control signal to the speaker output adjustment unit 5. The speaker face direction detection unit 4 selects an input signal from the microphone MICi corresponding to the location where the speaker is located based on the signal from the sound source position detection unit 2, and the input switching unit 5 The signal selected by the unit 4 is subjected to level control and delay control corresponding to the output signals to the speakers SPj (j = 1 to n), respectively. By applying a frequency characteristic corresponding respectively based on the control signal from the direction detecting unit 3, a speaker output adjusting section to be output to the plurality of loudspeakers 6 (SP1 to SPn).

The sound source position detection unit 2 monitors input signals from the plurality of microphones (MIC1 to MICm), and selects a microphone MICi having the highest input signal level among input signals of a predetermined level or higher as a sound source position (speaker position). It is determined that When the speaker stops speaking and there is no microphone having an input signal of a predetermined level or higher, it is determined that there is no sound source position.
Further, the sound source position detecting unit 2 outputs the input signal from the microphone MICi determined to be the sound source position from the plurality of speakers 5 (SP1 to SPn) and outputs it at any position in the room. A control signal for setting an output level and a delay time (delay) for signals output from the speakers (SP1 to SPn) so that the sound pressure level at the height of the listening position is uniform. 5 is output.
Here, the output signal level from each speaker is determined such that the sum of the direct sound from the speaker and the loud sound from the speaker is constant at any position in the room. That is, the output level of the speaker located far from the sound source position is controlled so as to compensate for the distance attenuation of the direct sound, and each speaker is calculated by calculation based on the distance between the sound source position (microphone position) and each speaker. The output level of the signal output from each speaker can be determined by creating a table in which the output level corresponding to each speaker is recorded in advance for each sound source position and referring to the table. It may be determined.
The delay amount gives a delay time corresponding to the time required for the direct sound emitted from the sound source position to reach each speaker position to the loudspeaker signal output from each speaker. It may be calculated based on the distance between the microphone position) and each speaker, or a table in which the delay time to each speaker is recorded in advance for each sound source position and the table is referred to. The delay amount may be determined by

The speaker face direction detection unit 3 detects a signal level for each frequency band of an input signal input from each of the microphones (MIC1 to MICm), and a direction in which the speaker's face is directed from the pattern. Is detected.
FIG. 2 is a diagram showing the directivity characteristics of human voices at five frequencies (100 Hz, 400 Hz, 1000 Hz, 4000 Hz, and 10,000 Hz) in a symmetric vertical plane passing through the mouth. In this figure, the direction of 0 ° indicates the front front of the mouth, and 270 ° indicates the direction of the top of the head.
As shown in this figure, the amount of voice reaching the back has a characteristic that it decreases as the frequency increases.
Therefore, the level for each frequency of signals input from the plurality of microphones 1 can be monitored, and the direction of the speaker's face can be determined from the pattern.
The speaker face direction detection unit 3 determines the direction of the speaker's face from the level pattern for each frequency for each of the input signals from the plurality of microphones 1 (MIC1 to MICm), and based on the result. Then, a control signal is output to the speaker output adjustment unit 5 so that a loudspeaker signal that emphasizes high frequencies is output from a speaker located behind the speaker. In this control signal, a control signal corresponding to the face direction and the distance of the sound source position from the microphone is stored in a table in advance, and the corresponding control signal based on the detection result of the face direction and the sound source position is stored in the table. And output to the speaker output adjustment unit 5.
In addition to the directivity characteristics in the vertical plane shown in FIG. 2, the orientation of the speaker's face may be detected with higher accuracy by referring to the directivity characteristics for each frequency in the horizontal plane.

The input switching unit 4 selects an input signal from the microphone based on an output signal from the sound source position detection unit 2 (a signal specifying a microphone detected as a sound source position), and adjusts the speaker output. Output to unit 5.
The speaker output adjusting unit 5 is configured to output each speaker based on a control signal supplied from the sound source position detecting unit 2 and the speaker face direction detecting unit 3 with respect to the input signal selected by the input switching unit 4. Set the output signal level, delay amount and frequency characteristics.
Here, when the speaker stops speaking, the sound source position detection unit 2 does not output a signal specifying the sound source position, and the input switching unit 3 does not output the input signal to the speaker output adjustment unit 4.
When another speaker starts speaking, the sound source position detection unit 2 determines that the microphone MICj in the vicinity of the newly started speaker is a sound source position, and a signal for identifying the microphone Is output to the input switching unit 4. As a result, this time, the input signal from the microphone MICj is supplied to the speaker output adjusting unit 5, and the output level and delay when the microphone MICj is the sound source position and the speaker face direction detecting unit 3 are detected. A loudspeaker signal having a frequency characteristic corresponding to the direction of the face of the new speaker is output from each speaker 6.

FIG. 3 is a diagram schematically illustrating the operation of the loudspeaker system of the present invention.
In this figure, (1) to (5) show examples of signal levels of direct incoming waves at positions behind and in front of the speaker, and positions (1) and (2) behind the speaker. 2 is affected by the frequency characteristics shown in FIG. 2 in addition to the distance attenuation according to the distance from the speaker. Note that (3) to (5) located in front are affected by distance attenuation. In addition, the signal reaching each position arrives with a propagation delay time corresponding to the distance from the speaker.
Here, in the loudspeaker system of the present invention, an input signal from a microphone (MIC3 in this example) located closest to the speaker is selected and input to the speaker output adjustment unit 5, and (1) to ( 5) The loudspeaker signal of the amount indicated by “*” is output from the speakers SP1, SP2, SP5, and SP6 corresponding to each position so that the listening level at each position in FIG. Control to do. At this time, a delay time corresponding to the distance from the speaker is added and output so that the timing is the same as the direct wave from the speaker. In the illustrated example, the loudspeakers SP3 and SP4 are controlled so as not to output a loud sound signal because the level of the direct wave from the speaker is large.
Thereby, it is possible to listen with uniform sound quality at each position in the room.

In addition, when a plurality of speakers are uttering at the same time and there are a plurality of sound sources, a plurality of voices can be simultaneously amplified. Hereinafter, a case where two types of sound amplification are performed will be described. When input signals from multiple microphones (MIC1 to MICm) are monitored and input signals above a certain level are in two microphones MICi and MICj, it is determined that the sound source is located in these two microphones MICi and MICj. , MICi, MICj are turned on (select signals from MICi, MICj). If a speaker near MICi stops speaking and no input signal exceeds a predetermined level in MICi, it is determined that there is no sound source at that position, and MICi is turned off. Furthermore, if it is determined that there is no sound source, and there is an input signal of a predetermined level or higher in another microphone MICk, it is determined that the sound source position has moved to the microphone or a new sound source has been generated, and a new MICk is newly generated. Turn on. When there are a plurality of sound sources, the output level of each speaker is set so that the sound pressure level is uniform at any position in the room, as in the case of the one system described above, for each microphone corresponding to the plurality of sound source positions. And the amount of delay is controlled and the sound is amplified. In this case, the input switching unit 3 selects input signals from a plurality of (for example, two) microphones, and the speaker output adjusting units 4 that can process the input signals of a plurality of systems, respectively. The level and delay amount of the signal output to each speaker may be controlled with respect to the input signal, and the output signals of both systems may be added and output to each speaker.
As described above, in the present invention, each microphone and each speaker have limited directivity (those having a narrow directivity angle), and the speaker output in the vicinity of the selected microphone is reduced. Since the speaker output far from the microphone is increased, there is less risk of howling, and the input from a plurality of microphones can be amplified simultaneously.

FIG. 4 is a diagram showing the configuration of a more specific embodiment of the loudspeaker system of the present invention. In this embodiment, up to two systems of input signals can be processed simultaneously.
In FIG. 4, the same components as those of FIG.
As described above, the input signals collected by the plurality of microphones 1 (MIC1 to MICm) distributed on the ceiling are amplified by the head amplifier group 11, and then converted into digital data by the A / D converter 12. Converted. Input signals from the microphones output from the A / D conversion unit 12 are input to the sound source position detection unit 2 and the speaker face direction detection unit 3 and are also supplied to the input switching unit 4.
As described above, the sound source position detection unit 2 has a speaker in an area in the vicinity of a microphone having the highest input signal level (within a range where sound is collected by the microphone) among input signals of a predetermined level or higher. And determines that the position of the microphone (MICi) is the sound source position, outputs information specifying the microphone determined to be the sound source position to the input switching unit 4, and outputs to be described later A control signal for controlling the level and delay amount of the signal output from each speaker when the microphone is at the sound source position is output to the level / delay control units 13 and 15.
Further, the speaker face direction detection unit 3 detects the direction of the speaker's face from the signal level pattern for each frequency of the input signal from each microphone, and each of the equalizer groups 14 and 16 described later A parameter for correcting the frequency characteristic corresponding to the direction of the speaker's face is output from the signal output from the speaker 6.

The input switching unit 4 has two outputs indicated by # 1 and # 2, and the input signal from the microphone determined to be the sound source position by the sound source position detection unit 2 is one of the two outputs. Selectively connect to. For example, when the input signal from the microphone is connected to the first output # 1 with respect to the sound source position detected first, and then the second speaker is detected, the input signal from the microphone is detected. To the second output # 2.
13 is an output for performing level control and delay time control for each speaker of the plurality of speakers 6 distributed to the input signal supplied through the first output # 1 of the input switching unit 4 It is a level / delay control unit, and output level / delay control units 13-1 to 13-n are individually provided for each speaker.
Reference numeral 14 denotes an equalizer group for correcting the frequency characteristics corresponding to the direction of the speaker described above with respect to the signals output from the output level / delay control unit 13, and individually corresponding to each speaker. Equalizers 14-1 to 14-n are provided.
Similarly, 15 is an output level / delay control unit corresponding to the second output # 2 of the input switching unit 4, and 16 is the direction of the speaker with respect to the signal output from the output level / delay control unit. It is an equalizer group for performing correction of frequency characteristics according to.

The input signal (signal collected by MICi) output from the first output # 1 of the input switching unit 4 is supplied to the output level / delay control unit 13 and the output level of each speaker of the speaker 6 / Delay controllers 13-1 to 13-n set levels and delay times according to the positional relationship between the microphone MICi and each speaker. The control signal for this setting is supplied from the sound source position detector 2 as described above. As a result, a signal having a time delay corresponding to the propagation delay time from the microphone MICi is output at an output level that can compensate for the distance attenuation from the microphone MICi for each speaker.
Then, output signals corresponding to the respective speakers from the output level / delay control unit 13 are input to equalizers 14-1 to 14-n provided for the respective speakers, where the speaker face direction detecting unit is provided. 3 is given a frequency characteristic that corrects the above-described frequency characteristic depending on the face direction of the speaker.
As a result, the equalizer group 14 outputs an output signal having the target value shown in FIG. 3, that is, a uniform output signal at any position in the room.

When the second speaker starts speaking and the sound source position detecting unit 2 detects the second sound source, the sound source position detecting unit 2 indicates a microphone (referred to as MICj) that is the sound source position. Information is supplied to the input switching unit 4, and an input signal from the microphone (MICj) is controlled to be connected to the second output # 2 of the input switching unit 4.
The input signal output via the second output # 2 is the output level / delay control unit 15 for the second system configured in the same manner as the output level / delay control unit 13 for the first system. As described above, after delay processing and level control corresponding to each speaker are performed, the equalizer group 16 configured in the same manner as the equalizer group 14 for the first system is used. The frequency characteristic for correcting the frequency characteristic depending on the direction of the signal is given and output to the mixer 17.

The input signal from the microphone group MICi from the equalizer group 14 is corrected for the output level, delay and frequency characteristics corresponding to each speaker, and the input signal from the microphone group MICj from the equalizer group 16 is corresponding to each speaker. The signals subjected to the correction of the output level, delay time, and frequency characteristics are added by the mixer 17 and converted into analog signals by the D / A converter group 18 respectively, and then amplified by the amplifier group 19 respectively. Output from each speaker 6 (SP1 to SPn).
Thereby, it is possible to listen to the pronunciation of the speaker at a uniform level and with high quality at any position in the room.

It is a block diagram which shows schematic structure of the loudspeaker system of this invention. It is a figure which shows the directional characteristic about five frequencies in the left-right symmetric vertical plane which passes along a mouth of a human voice. It is a figure which shows typically the operation | movement in the loudspeaker system of this invention. It is a block diagram which shows the structure of one Embodiment of the loudspeaker system of this invention.

Explanation of symbols

  1: microphone group, 2: sound source position detection unit, 3: speaker face direction detection unit, 4: input switching unit, 5: speaker output adjustment unit, 6: speaker group, 11: head amplifier, 12: A / D conversion Generator group, 13, 15: output level / delay control unit, 14, 16: equalizer group, 17: mixer, 18: D / A converter group, 19: power amplifier group

Claims (2)

A plurality of microphones distributed on the ceiling, each microphone having a limited directivity;
A plurality of speakers distributed on the ceiling, each speaker having a limited directivity;
Sound source position detecting means for detecting a sound source position based on input signals from the plurality of microphones;
Speaker face direction detecting means for detecting a speaker face direction based on input signals from the plurality of microphones;
A signal input from a microphone determined to be a sound source position by the sound source position detecting means, a gain according to a distance between the microphone and each speaker and a face direction detected by the speaker face direction detecting means, A loudspeaker system comprising: speaker output adjusting means for adjusting delay time and frequency characteristics and outputting to the plurality of speakers.   2. The loudspeaker system according to claim 1, wherein the speaker output adjusting means is configured to output input signals from a plurality of microphones to the plurality of speakers.

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