JP2006319448A - Loudspeaker system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure capable of positively preventing generation of howling even in an environment in which a microphone moves in a space provided with a speaker. <P>SOLUTION: A microphone 20 is fixed with a transmitter 10, and the position of the microphone 20 in the space in which a speaker array 60 is installed is detected on the basis of arrival time difference of a radio wave signal transmitted from the transmitter 10 to each of receivers 30. When the position of the microphone 20 is detected, directivity of an acoustic beam to be output from the speaker array 60 is controlled to suppress the feedback amount to the microphone 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a loudspeaker system, and more particularly to a loudspeaker system that suppresses howling.

When the microphone that collects the sound and the speaker that emits the collected sound are present in the same space, howling may occur depending on the relationship between the positions and orientations of the two. Howling is a phenomenon in which unpleasant noise is generated when the level of sound returning from the speaker to the microphone exceeds a predetermined value.
Conventionally, various attempts have been made to prevent the occurrence of this howling. For example, in a space where the positions of the speaker and the listener are separated, howling can be prevented by fixing the speaker toward the listener and allowing the speaker having a microphone to stop on the podium and speak.

Also, in a space where the position of the speaker and the listener is not separated, such as in a conference room, a switching operation such as discretely arranging multiple microphones and speakers and reducing the gain of the speakers near the speaker's microphone By doing this, howling can be prevented.
Furthermore, not only artificial preventive measures such as speaker placement and switching, but also a special mechanism for preventing howling is incorporated in the microphone and speaker hardware itself (see Patent Documents 1 to 3).
Japanese Patent Laid-Open No. 03-237899 Japanese Patent Laid-Open No. 08-084394 JP 2000-316199 A

However, the above kinds of howling prevention measures are based on the premise that the positional relationship between the microphone and the speaker is fixed. For introduction in an environment where a speaker carrying the microphone moves in space. It was unsuitable.
The present invention has been devised under such a background, and it is an object of the present invention to provide a mechanism that can reliably prevent occurrence of howling even in an environment in which a microphone moves in a space equipped with a speaker. To do.

  A loudspeaker system according to a preferred aspect of the present invention includes a sound collection unit that collects sound at an arbitrary position in a space, and a sound release unit that emits the sound collected by the sound collection unit toward the space. A sounding means; a detecting means for detecting the position of the sound collecting means in the space; and the amount of feedback from the sound emitted from the sound emitting means to the sound collecting means is suppressed to a predetermined value or less. Directivity control means for controlling the directivity of the sound means.

  In this system, storage means for storing each area obtained by dividing the space and directivity control information indicating a directivity control procedure when the sound collecting means is located in each area in association with each other. The directivity control means reads out the directivity control information stored in the storage means in association with the region containing the position detected by the detection means, and the control procedure indicated by the read directivity control information Accordingly, the directivity of the sound emitting means may be controlled.

  The sound emitting means is a speaker array in which a plurality of speaker units are arranged in a row, and each of the directivity control information stored in the storage means is supplied to each speaker unit of the speaker array. It may be information indicating the contents of signal processing to be individually applied to the audio signal.

  Further, the sound emitting means is a multi-cellular horn speaker in which a plurality of horn speakers are arranged substantially radially, and the directivity control means determines a feedback amount of the emitted sound to the sound collecting means by a predetermined value. In order to suppress to the following, the level of sound emitted from each of the plurality of horn speakers may be controlled.

  The sound emitting means includes a speaker and a speaker support that rotatably supports the speaker in an arbitrary direction, and the directivity control means supplies the sound to be emitted to the sound collecting means. In order to keep the feedback amount below a predetermined value, the rotation of the speaker via the speaker support may be controlled.

  A plurality of the sound collecting means; an identifier indicating each of the plurality of sound collecting means; and a storage means for storing the position information indicating the installation position of each of the sound collecting means in association with each other; Selecting means for selecting any of the sound collecting means, wherein the sound emitting means emits the sound collected by the sound collecting means selected by the selecting means, and the detecting means is selected by the selecting means. The installation position information stored in the storage means in association with the selected sound collection means identifier is read, and the installation position indicated by the read installation position information is specified as the position of the sound collection means in the space. May be.

  According to the present invention, howling can be reliably prevented even when the microphone moves in a space equipped with a speaker.

(Embodiment of the Invention)
This embodiment has the following two features. The first feature is that the voice of a speaker moving in a closed space such as a conference room or multipurpose hall is collected using a microphone, and the collected voice is amplified from a speaker array provided in the space. This is the point. The second feature is that howling is suppressed by controlling the directivity of the speaker array in accordance with the position of the microphone in the space.
In the following description, a sharp sound with directivity amplified from the speaker array is referred to as an “acoustic beam”.

  FIG. 1 is a block diagram showing a schematic configuration of a loudspeaker system according to the present embodiment. As shown in the figure, this system includes a transmitter 10, a microphone 20, receivers 30a to 30d, a microphone position detecting device 40, a microphone head amplifier 50, speaker arrays 60a to 60d, a speaker directivity controller 70, and a speaker. It is composed of power amplifiers 80a to 80d.

  The transmitter 10 is fixed to the microphone 20 and transmits radio signals with time stamps at predetermined time intervals. The receivers 30a to 30d are provided at a predetermined distance in the space, and each supply a radio signal received from the transmitter 10 to the microphone position detection device 40. The microphone position detecting device 40 detects the position of the microphone 20 in the space based on the arrival time difference of the radio signal with the same time stamp to each of the receivers 30a to 30d, and the coordinate information indicating the detected position is displayed on the speaker. Supplied to the directivity controller 70.

The microphone head amplifier 50 is connected to the microphone 20 and the speaker directivity controller 70 via a cable, and supplies an audio signal input from the microphone 20 to the speaker directivity controller 70.
Each of the speaker arrays 60a to 60d includes four speaker units 61 to 64 arranged in a row, and the speaker units 61 to 64 of each speaker array 60a to 60d are audio signals that have undergone signal processing by the speaker directivity controller 70. Signals are respectively supplied via speaker power amplifiers 80a to 80d. Then, each of the speaker units 61 to 64 outputs a sound generated based on the supplied audio signal as an acoustic beam.

FIG. 2 is a block diagram illustrating a hardware configuration of the speaker directivity controller 70. As shown in the figure, the controller 70 includes a signal separation / branching unit 71, signal processing units 72 a to 72 d, a control unit 73, and a control information storage table 74. Each of the signal processing units 72a to 72d corresponds to the speaker arrays 60a to 60d, and includes four signal processing systems in which a delay device 75 and an amplifier 76 are connected. Each signal processing system incorporated in each of the signal processing units 72a to 72d manages signal processing of audio signals supplied to the speaker units 61 to 64 of the speaker arrays 60a to 60d, respectively.
The audio signal supplied from the microphone head amplifier 50 is separated into a plurality of audio signals having the same waveform by the signal separation / branching unit 71 and supplied to each signal processing system of the signal processing units 72a to 72d. Each signal processing system performs individual signal processing on the audio signal supplied thereto under the control of the control unit 73 and then supplies the audio signal to each of the speaker units 61 to 64 of the speaker arrays 60a to 60d. By appropriately controlling the delay amount provided by the delay device 75 of each signal processing system and the amplification amount provided by the amplifier 76 for the audio signal, an acoustic beam having an arbitrary directivity is output from the speaker arrays 60a to 60d. Can do.

In FIG. 2, the control information storage table 74 is an aggregate of a plurality of cells each corresponding to 16 regions obtained by dividing the space into four equal parts in the vertical and horizontal directions. Directivity control information is stored in each cell of this table. The directivity control information is a collection of parameters that determine the content of signal processing to be executed by each signal processing system of the signal processing units 72a to 72d. The sound from the speaker array 60 when the microphone 20 is positioned in each region. It is obtained based on the result of simulating the feedback amount.
The control unit 73 identifies the position of the microphone 20 based on the coordinate information supplied from the microphone position detection device 40, and signals each parameter stored as directivity control information in a cell corresponding to the region including the position. It is set for each signal processing system of the processing units 72a to 72d.

  Here, a procedure for acquiring parameters to be stored as directivity control information in each cell of the control information storage table 74 will be described in detail with reference to FIG. FIG. 3 is an overhead view showing an example of a space. The space shown in the figure is partitioned from the outside by four side walls 91 to 94, and each space can be divided into 16 areas corresponding to the cells of the control information storage table 74. Further, four speaker arrays 60a to 60d are fixed to the four corners of the space, respectively, substantially toward the center.

In this figure, attention is focused on a parameter acquisition procedure for controlling the directivity of the acoustic beam output from the lower left speaker array 60a. As described above, since the speaker arrays 60a to 60d are fixed toward the substantially center, audio signals that are not subjected to signal processing by the speaker directivity controller 70 are transmitted from the microphone head amplifier 50 to the speakers of the speaker array 60a. If supplied to the units 61a to 64a, the path of the acoustic beam output from the speaker unit 60a coincides with the line N, and the gain fed back to the microphone 20 at the position P on the path increases. Howling will occur.
On the other hand, for example, if the path of the acoustic beam coincides with the line A in the figure, any path of the direct wave that reaches the side wall 92 and the primary reflected wave that reaches the side wall 91 via the side wall 92 is selected. Cannot pass through the region X including the position P, and howling can be reliably suppressed.

  In this embodiment, after first determining an ideal acoustic beam path in which neither the direct wave nor the primary reflected wave can pass through the region X including the position P of the microphone 20, Parameters for each signal processing system for realizing such an acoustic beam are individually acquired. For example, in order to make the path of the acoustic beam coincide with the line A in the figure, the delay amount of the audio signal supplied to the speaker unit 61a disposed at the right end of the speaker array 60a is maximized, and the left speaker unit 61b to The delay amount of the audio signal supplied to 61d may be reduced stepwise.

Similarly, for the parameters to be set for each signal processing system of the other speaker arrays 60b to 60d, the ideal acoustic beam path is first determined, and the parameters for each signal processing system for realizing these paths are sequentially acquired. To go. However, it is desirable that the path of the acoustic beam output from each of the speaker arrays 60a to 60d is determined in consideration of a balance that can make the sound pressure level in the space substantially uniform.
FIG. 4 shows an example of determining a desired route that satisfies this requirement. In this figure, the acoustic beam A of the speaker array 60a has a path that reaches the side wall 92 as a primary wave after reaching the side wall 92 as a direct wave. The acoustic beam B of the speaker array 60b has a path that reaches the side wall 94 as a primary reflected wave after reaching the side wall 91 as a direct wave, and the acoustic beam C of the speaker array 60c and the acoustic of the speaker array 60d. The beam D is a path that reaches the side wall 91 as a primary reflected wave after reaching the side wall 93 as a direct wave. Referring to the path of each acoustic beam shown in the figure, it is adjusted so that at least one of the direct wave or the primary reflected wave of any acoustic beam passes through all areas except the area X including the position P of the microphone 20. I understand that. By adjusting between the paths, it is possible to make the sound pressure levels in the other regions substantially uniform while reliably suppressing the occurrence of howling in the region X including the position P.
When acquisition of parameters corresponding to the four speaker arrays 60a to 60d is completed, directivity control information in which these parameters are collected is stored in a cell corresponding to the region X. By repeating the same operation while moving the region X, all directivity control information to be stored in the cells of the control information storage table 74 can be acquired.

  According to the present embodiment described above, the position of the microphone 20 in the space provided with the speaker array 60 and the microphone 20 is detected, and the directivity of each speaker array 60 is set so that the acoustic beam avoids the position of the microphone 20. Control. Thus, no matter how the speaker carrying the microphone 20 moves to the space, howling can be reliably suppressed.

(Other embodiments)
This embodiment can be modified in various ways.
In the above embodiment, a radio signal is transmitted from the transmitter 10 fixed to the microphone 20 and the position of the microphone 20 is detected based on the time difference at which each receiver 30 receives the radio signal. The position of the microphone 20 may be specified by exchanging ultrasonic waves or infrared rays between the receiver and the receiver 30.
Also, a plurality of microphones 20 may be installed in the space, and the sound of the microphones 20 selected by switching may be emitted from the speaker array 60 into the space. In the loudspeaker system according to this modification, a plurality of microphones 20 fixed in each area of the space, and a switcher that is a means for supplying only the audio signal of one microphone 20 to the microphone head amplifier 50. With. Further, the memory in the system stores a table in which identifiers indicating the microphones 20 are associated with installation position information indicating their installation positions. When a certain microphone 20 is selected by the switcher, the installation position indicated by the installation position information stored in the memory in association with the identifier of the microphone 20 is specified, and an acoustic beam that avoids the installation position is emitted. Thus, the directivity of the speaker array 60 is controlled.

The speaker array 60 in the above embodiment has four speaker units 61 to 64 arranged in a row, but these may be arranged in a plane. Further, the number of speaker units constituting one speaker array does not have to be four, and may be any number as long as it is plural.
In the above embodiment, the speaker array 60 is fixed at the four corners of the space. However, the speaker array 60 may be arranged in a different space. For example, a plurality of speaker arrays 60 may be discretely embedded in the ceiling of a room, and the directivity of each speaker array 60 may be individually controlled according to the detected position of the microphone 20.

In the above embodiment, the speaker array 60 is employed as sound emitting means in the space, and the directivity is obtained by performing signal processing such as delay and amplification on the audio signal supplied to each speaker unit 61 of the speaker array 60. Was controlling. On the other hand, you may control the directivity of a sound emission means using another method. For example, the gain of the sound emitted from the sound emitting means farthest from the detected position of the microphone 20 may be increased while the gain of the sound emitted from the nearest sound emitting means may be lowered.
Further, the speaker array 60 may be replaced with a multi-cellular horn speaker. The multi-cellular horn is formed by arranging substantially the same type of horn loudspeaker so that its opening surface forms a part of a spherical surface. In this modification, when the position of the microphone 20 is detected, control is performed such as reducing only the gain of the horn speaker serving the area including the position in order to keep the feedback amount to the microphone 20 below a predetermined value. .
Furthermore, a speaker as a sound emitting means is installed at a predetermined position in the space via a speaker support that rotatably supports the direction of the speaker in an arbitrary direction, and the speaker is rotated via the speaker support. You may make it control according to 20 detection positions.

  When the microphone 20 has a relatively strong directivity, the direction of the microphone 20 may also be detected using various sensors, and the gain of the sound output from the sound emitting means may be adjusted according to the detected direction.

It is a schematic block diagram of a loudspeaker system. It is a hardware block diagram of a speaker directivity controller. It is a figure which shows the course of an acoustic beam. It is a figure which shows the course of an acoustic beam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Microphone, 30 ... Receiver, 40 ... Microphone position detection apparatus, 50 ... Microphone head amplifier, 60 ... Speaker array, 61 ... Speaker unit, 70 ... Speaker directivity controller, 71 ... Signal separation branching unit, 72 ... Signal Processing unit 73 ... Control unit 74 ... Control information storage table

Claims (6)

Sound collecting means for collecting sound at an arbitrary position in a certain space;
Sound emitting means for emitting the sound collected by the sound collecting means toward the space;
Detecting means for detecting the position of the sound collecting means in the space;
A loudspeaker system comprising: directivity control means for controlling directivity of the sound emitting means so as to suppress a feedback amount of the sound emitted from the sound emitting means to the sound collecting means to be equal to or less than a predetermined value. The loudspeaker system according to claim 1,
Each of the areas obtained by dividing the space, and storage means for storing the directivity control information indicating the directivity control procedure when the sound collecting means is located in each of the areas, respectively, are further stored.
The directivity control means includes
The directivity control information stored in the storage means is read in association with the area containing the position detected by the detection means, and the directivity of the sound emitting means is controlled according to the control procedure indicated by the read directivity control information. Loudspeaker system. The loudspeaker system according to claim 2,
The sound emitting means is
A speaker array with a plurality of speaker units,
Each of the directivity control information stored in the storage means is
A loudspeaker system, which is information indicating the contents of signal processing to be individually applied to audio signals supplied to the respective speaker units of the speaker array. The loudspeaker system according to claim 1,
The sound emitting means is
A multi-cellular horn speaker in which a plurality of horn speakers are arranged substantially radially,
The directivity control means includes
A loudspeaker system for controlling a level of sound emitted from each of the plurality of horn speakers so as to suppress a return amount of the emitted sound to the sound collecting means to a predetermined value or less. The loudspeaker system according to claim 1,
The sound emitting means is
Speakers,
A speaker support that rotatably supports the speaker in an arbitrary direction;
The directivity control means includes
A loudspeaker system that controls the rotation of the speaker via the speaker support so as to suppress the amount of feedback of the emitted sound to the sound collecting means below a predetermined value. The loudspeaker system according to claim 1,
A plurality of the sound collecting means;
Storage means for storing an identifier indicating each of the plurality of sound collection means and installation position information indicating the installation position of each of the sound collection means in association with each other;
Selecting means for selecting any of the plurality of sound collecting means;
The sound emitting means is
Releases the sound collected by the sound collecting means selected by the selecting means,
The detection means includes
The installation position information stored in the storage unit in association with the sound collection unit identifier selected by the selection unit is read, and the installation position indicated by the read installation position information is set as the position of the sound collection unit in the space. Identify loudspeaker systems.

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