JP2014197771A - Broadcast system sound output controller and method for controlling sound output - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a broadcast system sound output controller and a method for controlling the sound output capable of automatically controlling a sound volume, etc., corresponding to a change in a noise environment by using a simple configuration.SOLUTION: A noise detection unit compares a sound signal detected by three microphones disposed separately from each other and a sound signal transmitted from a broadcast program transmission unit, and extracts a noise signal at each microphone position. A noise source position calculation unit specifies the position of a noise source from the noise detection signals at the three microphones and information about the positions of the three microphones. A noise source sound pressure calculation unit calculates the sound pressure level of noise at the noise source from information about the prescribed microphone positions, information about the position of the noise source, and information about the sound pressure level of the noise detected by a prescribed microphone. A control value calculation unit calculates the control value of a sound signal to be outputted from the information about the position of the noise source, information about the sound pressure of the noise source, and information about speaker positions.

Description

  The present invention relates to an audio output control apparatus and an audio output control method for a broadcasting system.

  The volume is automatically adjusted in response to changes in the noise environment in a voice guidance system that provides voice guidance and music broadcasts to a large number of unspecified pedestrians, etc., in a predetermined area such as a station premises or a predetermined range of roads. Control systems have been proposed.

  For example, Patent Document 1 describes a device that detects the loudness of a microphone with a microphone installed in the vicinity of the loudspeaker and controls the output volume of the loudspeaker according to the detected loudness. In Patent Document 2, the amount of attenuation of the sound pressure level that is attenuated before the sound is transmitted to the target person from information such as the number of visitors in the railway station, the installation status of the microphones, and the presence or absence of the train An apparatus that evaluates each frequency band and corrects an acoustic signal to be output based on the evaluation result is described.

JP-A-8-317497 JP 2011-193084 A

  In the devices described in Patent Documents 1 and 2, it is necessary to install the same number of microphones as the area sections to be controlled. Furthermore, the apparatus described in Patent Document 2 is complicated and requires a great deal of cost to realize it.

  An object of the present invention is to provide an audio output control apparatus and an audio output control method for a broadcast system that can automatically control volume and the like in response to a change in a noise environment with a simple configuration.

In order to solve the above problems, the present invention provides the following apparatus and method.
(1) A noise signal extraction unit (502) that compares a sound signal detected from three microphones with a broadcast program signal and extracts a noise detection signal in each of the three microphones, and noise detection in each of the three microphones A noise source position calculation unit (503) for specifying a position of a noise source from a signal and position information of the three microphones; and a predetermined microphone of the three microphones; The distance between the predetermined microphone and the noise source is calculated as distance information from the position information of the noise source, and the noise is detected from the sound pressure level information of the noise detected by the predetermined microphone and the distance information. A noise source sound pressure calculation unit (504) for calculating a sound pressure level of the noise at the source, position information of the noise source, sound pressure level information of the noise source, and position of the speaker And a control value calculation unit (505) for calculating a control value for controlling an audio signal output from the speaker according to a sound pressure level of the noise at the speaker position calculated from the information. An audio output control device for a broadcasting system.

  (2) comparing the audio signal detected from each of the three microphones with the broadcast program signal to extract a noise detection signal in each of the three microphones; the noise detection signal in each of the three microphones; A step of identifying a position of a noise source from position information of each of the two microphones, and a predetermined microphone among the three microphones based on the position information of the predetermined microphone and the position information of the noise source. And calculating the sound pressure level of the noise at the noise source from the sound pressure level information of the noise detected by the predetermined microphone and the distance information. The speaker position calculated from the position information of the noise source, the sound pressure level information of the noise source, and the position information of the speaker. Kicking in response to said sound pressure level of the noise, the sound output control method of a broadcasting system, characterized by a step of calculating a control value for controlling the audio signal to be output from the speaker.

  According to the present invention, it is possible to provide an audio output control device and an audio output control method for a broadcasting system that can automatically control the volume and the like in response to changes in the noise environment with a simple configuration.

It is a figure which shows the example of arrangement | positioning of the speaker and microphone of the broadcasting system which concern on 1st Embodiment. It is a block diagram for demonstrating the structure of the broadcast system which concerns on 1st Embodiment. It is a flowchart for demonstrating the flow of the process which concerns on 1st Embodiment. It is a figure showing the position of the noise source in 1st Embodiment. It is an example of the table which calculates | requires the sound pressure level of the noise in each speaker position from the sound pressure level of a noise source, and the distance from a noise source to each speaker. It is an example of the table which calculates | requires the correction value of each speaker level from the sound pressure level of the noise in each speaker position. It is an example of the table which calculates | requires the correction value of a speaker level directly from the sound pressure level Sn of a noise source, and the distance from a noise source to each speaker. It is a figure showing the position of the noise source in the modification of 1st Embodiment. It is a figure which shows the example of arrangement | positioning of the speaker and microphone of the broadcast system which concern on 2nd Embodiment. It is a block diagram for demonstrating the structure of the broadcast system which concerns on 2nd Embodiment. It is a figure for demonstrating the directivity of the microphone in 2nd Embodiment. It is a figure for demonstrating how to obtain | require the direction of the noise source in 2nd Embodiment.

  Hereinafter, an embodiment of a broadcasting system according to the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
As shown in FIG. 1, the broadcasting system 1 according to the present embodiment includes a plurality of speakers (SP101 to SP112) and three microphones (MIC 201 to 203) installed in a station premises or on the ceiling of a wide hall. Is done. The number of speakers can be arbitrarily set according to the size of the installation place and the application, but in this embodiment, the number of speakers is 12. The MICs 201 to 203 are noise detection microphones, and are installed at a predetermined distance from each other.

  The configuration of the broadcasting system according to this embodiment will be described with reference to FIG. The MICs 201 to 203 detect audio and send the detected audio signals to the AMPs 301 to 303, respectively. The AMPs 301 to 303 amplify the audio signals and send them to the ADs 401 to 403, respectively. The AD 401 to 403 convert the received audio signal into a digital signal and send it to the arithmetic unit 500.

  The calculation unit 500 includes a semiconductor circuit including a central processing unit (CPU), a ROM storing a program, and a RAM as a work area, and includes a position information holding unit 501, a noise signal extraction unit 502, and a noise source position calculation unit. 503, function as a noise source sound pressure calculation unit 504, and a control value calculation unit 505.

  The position information holding unit 501 stores position information of each microphone and speaker as three-dimensional coordinates. As for coordinates, for example, as shown in FIG. 1, an X coordinate and a Y coordinate are defined based on an arbitrary position of the ceiling, and a height direction is a Z coordinate. In the present embodiment, since the microphone and the speaker are all installed on the ceiling, the Z coordinate is zero. For example, the coordinates of the MIC 203 are (18, 10, 0). The microphone and the speaker need not be arranged on the ceiling, and the Z coordinate may not be zero. The position information may be set and stored at the time of system design or installation.

  The calculation unit 500 calculates the position of the noise source and the sound pressure level of the noise according to the procedure described later, and outputs a control signal for controlling the audio signal output from each speaker based on the calculation result.

  The broadcast program sending unit 600 branches and sends a broadcast program signal such as music or voice guidance by the number corresponding to the number of speakers. The broadcast program may be input from outside the system, or the broadcast program may be stored in a storage medium connected or interpolated to the system. In this embodiment, since the number of speakers is 12, the broadcast program sending unit 600 branches to 12 and sends it. EVs 701 to 712 are electronic volumes, which adjust the level of the signal received from the broadcast program sending unit 600 based on the control signal received from the calculation unit 500, and send the signals to the AMPs 801 to 812, respectively.

  The AMPs 801 to 812 amplify the received signals and send them to the speakers 101 to 112, respectively. The speakers 101 to 112 each output a level-adjusted broadcast program. The broadcast program transmitted from the broadcast program transmission unit 600 does not have to be one type, and may be broadcast with different programs for each speaker, or may be broadcast with BGM or the like superimposed.

Further, the processing flow will be described with reference to the flowchart of FIG.
In step S1, the noise signal extraction unit 502 compares the microphone detection signal received from the AD 401 to 403 with the broadcast program signal received from the broadcast program transmission unit 600, and outputs a signal other than the broadcast program as a noise signal from each microphone. Extract as Since the positions of the speakers and microphones are fixed, the noise signal can be extracted by presetting the detection level of the broadcast program detected by each microphone and subtracting from the signal detected by each microphone. Even when there are a plurality of types of broadcast programs, the broadcast programs generated from this system are not detected as noise.

  In step S <b> 2, the noise source position calculation unit 503 specifies the position of the noise source based on the noise signal detected by the noise signal detection unit 502. The time taken for the noise generated from the noise source to reach each microphone increases in proportion to the distance from the noise source to the microphone. In this embodiment, since each microphone is installed at a predetermined distance from each other, the difference in distance from the noise source to each microphone can be calculated by comparing the noise detection time at each microphone. . Further, the position where the noise source may exist can be estimated from the difference in distance from the noise source to each microphone.

Of the three microphones, the noise detection times of two microphones (referred to as microphone A and microphone B) are compared to estimate the position of the noise source. If the speed of sound is 340 m / sec, the difference ΔL (m) from the noise source to each microphone can be obtained by Equation (1) based on the noise detection time difference ΔT (msec).

  For example, assuming that the noise signal detection time of the microphone B is 7 msec later than the microphone A, the distance from the noise source to the microphone A is calculated as 2.38 m closer than the distance from the noise source to the microphone B from Equation 1. The In FIG. 4, it is assumed that the microphone A and the microphone B are installed 5 meters apart, and the distance between the noise source and the microphone A is 2.38 m closer than the distance from the noise source to the microphone B. The positional relationship is illustrated on a plane. A and B represent the positions of the microphones, and a curve indicated by a dotted line represents a position where a noise source may exist. In FIG. 4, for easy understanding, the coordinates of the microphone A are represented by two-dimensional coordinates with 0, but in reality, the position of the noise source needs to be estimated in a three-dimensional space, and the noise source exists. Possible positions are indicated by curved surfaces in the three-dimensional space. (Not shown)

  As described above, the position where the noise source may be present can be represented by a curved surface from the noise detection time difference between the two microphones selected from the three microphones. This curved surface is obtained for three combinations of MIC 201 and MIC 202, MIC 202 and MIC 203, and MIC 203 and MIC 201, and the position corresponding to the intersection of the curved surfaces obtained by each combination is obtained, whereby the position of the noise source can be specified. .

In step S3, the noise source sound pressure calculation unit 504 calculates the sound pressure level of the noise source. One arbitrary microphone (for example, a microphone with the highest noise detection level) is selected from the three microphones, and the distance between the selected microphone and the noise source is calculated from the position information of the noise source specified above. Assuming that the coordinates of the noise source are (Xo, Yo, Zo) and the coordinates of the microphone A are (Xa, Ya, 0), the distance La from the noise source to the microphone A can be obtained by Equation 2.

Since the sound pressure level of the noise detected by the microphone is inversely proportional to the square of the distance from the noise source to the microphone, the sound source level of the noise source is determined from the sound pressure level of the noise detected by the selected microphone and the distance information to the noise source. The sound pressure level can be calculated. Here, the sound pressure level normalized at a position 1 m away from the noise source is defined as the sound pressure level of the noise source. Assuming that the distance from the noise source to the microphone is La (m) and the sound pressure level of the noise at the microphone position is S (dB), the sound pressure level So (dB) of the noise source can be obtained by Equation 3.

After step S4, the output level of each speaker is set.
The number of speakers is k, and serial numbers from 1 to k are assigned to each speaker. The order of sequential number assignment can be arbitrarily set. In step S4, a speaker is selected. In step S5, the sound pressure level of the noise assumed at the selected speaker position is calculated. When the sound pressure level of the noise source is So (dB) and the distance from the noise source to the nth speaker is Ln, the sound pressure level Sn (dB) of the noise at the position of the nth speaker is obtained by Equation 4. be able to.

In step S6, the control value calculation unit 505 calculates a correction value Gn (dB) for the selected speaker using Expression (5).

  That is, when the sound pressure level Sn of the noise at the speaker position is 65 dB or less, the influence of noise is not an issue, so the correction value of the speaker is set to 0 dB. When the sound pressure level Sn of the noise at the speaker position is greater than 65 dB and 90 dB or less, the correction value of the speaker is set to be large according to the sound pressure level of the noise. However, if the correction value of the speaker is larger than 25 dB, the sound of the speaker itself becomes too loud and uncomfortable for people near the speaker. Therefore, when the sound pressure level Sn of the noise at the speaker position is larger than 90 dB Fixes the correction value of the speaker to 25 dB. The setting of the correction range and the correction value is not limited thereto, and may be arbitrarily set depending on the performance of the broadcasting system and the installation environment.

  The correction value Gn calculated by the control value calculation unit 505 is sent to the EVs 701 to 712 as correction data. In step S7, the EVs 701 to 712 correct the audio signal level to be sent to the selected speaker. In step S8, it is determined whether n is equal to k. If n = k, the process proceeds to step S4. In step S4, n = n + 1 is set, and this is repeated until n = k. If it is determined in step S8 that n = k, it is determined that correction has been completed for all speakers, and the process ends. The correction value once set is held, and the level is set based on this correction value until the next correction value is calculated.

  The method for deriving the correction value is not limited to the arithmetic processing, and a table calculated in advance may be stored in the correction value calculation unit 505 and obtained based on the table. FIG. 5 shows an example of a table for obtaining the sound pressure level of noise at each speaker position from the sound pressure level Sn of the noise source and the distance from the noise source to each speaker. For example, when the sound pressure level Sn of the noise source is 62 dB or more and less than 64 dB and the distance from the noise source to the speaker position is 4.0 m or more and less than 4.8 m, the sound pressure level of the noise at the speaker position is obtained as 50 dB. It is done.

  FIG. 6 shows an example of a table for obtaining a correction value from the sound pressure level of noise at each speaker position. For example, when the sound pressure level of noise is 67 dB or more and less than 68 dB, the correction value Gn is +2 dB. Further, as shown in FIG. 7 as an example, a table for directly obtaining a correction value from the sound pressure level Sn of the noise source and the distance from the noise source to the speaker may be used. For example, when the sound pressure level of the noise source is 80 dB or more and less than 82 dB, and the distance from the noise source to the speaker is 1.7 m or more and less than 2 m, the correction value is 10 dB. By using these tables, the calculation load can be reduced.

  The above control may be performed at predetermined time intervals set in advance, for example, by providing the arithmetic unit 500 with a timer function. Further, it may be performed when the noise detection level of any speaker changes by a predetermined level or more.

  As described above, in the present embodiment, even when many speakers are installed, the sound output of each speaker can be corrected appropriately only by installing three microphones.

(Modification)
In the above description, the noise source position calculation unit identifies the position of the noise source by comparing the detection time difference of the noise signal detected by each speaker. However, when the noise is only a low-frequency component, this method may not improve the accuracy of specifying the noise source position.

Since the magnitude of noise detected by each microphone is inversely proportional to the square of the distance from the noise source to the microphone, the position of the noise source can be specified by comparing the noise level detected by each microphone. Of the three microphones, the noise detection levels of two microphones (referred to as microphone A and microphone B) are compared to estimate the position of the noise source. Assuming that the distance from the noise source to the microphone A is La and the distance from the noise source to the microphone B is Lb, the ratio of La and Lb is obtained from the noise detection level difference ΔS (dB) by the equation (6).

  FIG. 8 shows that the microphone A and the microphone B are installed 5 meters apart from each other when the sound pressure level of the noise detected by the microphone B is 3 dB lower than the sound pressure level of the noise detected by the microphone A. The positional relationship of noise sources is illustrated on a plane. A and B represent the positions of the microphones, and a curve indicated by a dotted line represents a position where a noise source may exist. Actually, it is necessary to estimate the position of the noise source in the three-dimensional space, and the position where the noise source may exist is indicated by a curved surface in the three-dimensional space. (Not shown)

  As described above, the position where the noise source may exist can be represented by a curved surface from the difference in the sound pressure level of the noise detected by the two microphones selected from the three microphones. The curved surface is obtained for three combinations of MIC 201 and MIC 202, MIC 202 and MIC 203, and MIC 203 and MIC 201, and the position corresponding to the intersection is obtained, whereby the position of the noise source can be specified.

  Either the method of specifying the position of the noise source by the difference in detection time of the noise signal in each microphone or the method of specifying the position of the noise source by the difference in detection level of the noise signal by each microphone can be used alone, but they are used in combination. You may do it. For example, if the noise signal contains a high-frequency component, it is determined by the difference in detection time at each microphone, and if the noise signal is only a low-frequency component, the noise signal detection level difference at each microphone is used. It becomes possible to specify the position of the source.

  As described above, in the present embodiment, the volume of the plurality of speakers can be adjusted appropriately by detecting the noise signal with three microphones.

(Embodiment 2)
In the present embodiment, the configuration for detecting the position of the noise source is partially different from that in the first embodiment. In the drawings for explaining the present embodiment, the same or similar parts as those in the first embodiment are given the same numbers, and the explanation may be omitted. As shown in FIG. 9, in this embodiment, directional microphones MIC205 to MIC207 and an omnidirectional microphone MIC208 are arranged. The MICs 205 to MIC 207 are arranged at one location in which the directivity directions of the microphones are different by 120 °, and the MIC 208 is arranged apart from the MICs 205 to MIC 207.

  As shown in FIG. 10, the broadcasting system 2 according to the present embodiment has a common configuration with respect to the broadcasting system 1 of the first embodiment except that one microphone input system is added. MICs 205 to 207 indicate directional microphones, and MIC 208 indicates an omnidirectional microphone. The AMPs 305 to 308 amplify the noise signal detected by each microphone. The ADs 405 to 408 convert the noise signal detected by each microphone into a digital signal and send it to the calculation unit 500. The noise source position calculation unit 503 specifies the position of the noise source based on the signals detected by the four microphones. Except for the above, this embodiment is the same as FIG. 2 described in the first embodiment.

  FIG. 11 shows a diagram in which the directivity characteristics on the horizontal plane of three directional microphones are drawn in a circular shape (the amplitude axis is a linear scale). The noise signal level detected by the three directional microphones for noise generated at a specific time from the noise source is proportional to the directional sensitivity of the horizontal plane angle of each microphone, so that the noise signal level detected by the three directional microphones The direction of the noise source can be specified by comparing

  A method of obtaining the direction of the noise source will be briefly described with reference to FIG. For example, when the noise signal levels detected by the MIC 205 and the MIC 206 are compared, and the noise signal level of the MIC 206 is larger, the direction of the noise source is found to be between 60 ° and 240 °. Similarly, the noise signal levels detected by the MIC 205 and the MIC 207 are compared. If the noise signal level of the MIC 205 is larger, the direction of the noise source is between 300 ° and 0 °, or between 0 ° and 120 °. I understand that. Combining these two results, it can be seen that the noise source is between 60 ° and 120 °, and since the magnitude of the difference is known, a specific angle can also be specified. Actually, the direction may be specified by calculation from the noise signal detection level difference between the microphones.

  If the direction of the noise source can be specified by the detection signals of MIC 205 to MIC 207, the detection level of MIC 208 installed apart from MIC 205 to MIC 207 is compared with the detection level of one microphone of MIC 205 to MIC 207. Thus, the distance from the noise source to each microphone can be calculated. As a result, the position of the noise source can be specified. Since the distance calculation method is the same as that described in the first embodiment, the description thereof is omitted.

  In this embodiment, the directivity directions of the three directional microphones are arranged in different directions by 120 °. However, the present invention is not limited to this, as long as the directivity directions are substantially equal and the angles of the directivity directions are known. In this embodiment, the difference between the noise signal detection levels of the two microphones is used for specifying the distance from the noise source. However, as described in the first embodiment, the time difference between the waveforms may be used, or both may be used in combination. good.

  In this embodiment, the volume adjustment of a plurality of speakers can be appropriately performed by detecting a noise signal with three directional microphones and one omnidirectional microphone. In addition, since the speaker can be installed in two places, the installation is easier than in the first embodiment.

  In the first and second embodiments, only the volume control of each speaker is performed. However, the configuration may be such that the sound quality is controlled, and the control of the volume and the sound quality may be combined. For example, it is more effective to increase the sound level output from the speaker as the noise increases and to emphasize the high-frequency component of the signal. In this case, EVs 701 to 712 in FIGS. 2 and 10 may be replaced with an equalizer that operates the frequency characteristics.

  In the second embodiment, an example in which a noise signal is detected with three directional microphones and one omnidirectional microphone is shown, but four directional microphones may be used without using the omnidirectional microphone. The microphone used in the first embodiment may be a directional microphone or an omnidirectional microphone, and a directional microphone and an omnidirectional microphone may be mixed.

1, 2 broadcasting system, 101-112 speaker, 201-203 microphone,
205-208 microphone, 500 arithmetic unit, 501 position information holding unit,
502 noise signal extraction unit, 503 noise source position calculation unit,
504 noise source sound pressure calculation unit, 505 control value calculation unit,
600 broadcast program sending part, 701-712 electronic volume,

Claims (6)

A noise signal extraction unit that compares the audio signal detected from the three microphones with the broadcast program signal and extracts a noise detection signal in each of the three microphones;
A noise source position calculation unit that specifies a position of a noise source from a noise detection signal in each of the three microphones and position information of the three microphones;
In a predetermined microphone among the three microphones, a distance between the predetermined microphone and the noise source is calculated as distance information from position information of the predetermined microphone and position information of the noise source, and the predetermined microphone A noise source sound pressure calculation unit for calculating a sound pressure level of the noise in the noise source from the sound pressure level information of the noise detected by the microphone and the distance information;
The sound signal output from the speaker is controlled according to the sound pressure level of the noise at the speaker position calculated from the position information of the noise source, the sound pressure level information of the noise source, and the position information of the speaker. An audio output control device for a broadcasting system, comprising: a control value calculation unit that calculates a control value for The noise source position calculation unit
The position of the noise source is specified by comparing the noise detection signal and position information of each microphone in three different combinations of selecting two microphones from the three microphones. Audio output control device for broadcasting system. The noise source position calculation unit
The sound output control of the broadcast system according to claim 1 or 2, wherein a position of the noise source is specified by comparing a detection time of the noise detection signal in each of the three microphones and position information of each microphone. apparatus. The noise source position detector
The sound output control of the broadcasting system according to claim 1 or 2, wherein a position of the noise source is specified by comparing a detection level of the noise detection signal in each of the three microphones and position information of each microphone. apparatus. The noise source position detector
Analyzing the frequency component of the noise signal;
When the noise signal includes a frequency component higher than a predetermined frequency, the detection time of the noise detection signal in each of the three microphones is compared with the position information of each microphone to identify the position of the noise source,
When the audio signal does not include a frequency component higher than a predetermined frequency, the detection level of the noise detection signal in each of the three microphones is compared with the position information of each microphone to identify the position of the noise source. 3. The audio output control apparatus for a broadcasting system according to claim 1 or 2. Comparing the audio signal detected from each of the three microphones with the broadcast program signal, and extracting the noise detection signal in each of the three microphones;
Identifying a noise source position from a noise detection signal in each of the three microphones and position information of each of the three microphones;
In a predetermined microphone among the three microphones, a distance between the predetermined microphone and the noise source is calculated as distance information from position information of the predetermined microphone and position information of the noise source, and the predetermined microphone Calculating the sound pressure level of the noise at the noise source from the sound pressure level information of the noise detected by the microphone and the distance information;
The sound signal output from the speaker is controlled according to the sound pressure level of the noise at the speaker position calculated from the position information of the noise source, the sound pressure level information of the noise source, and the position information of the speaker. And a step of calculating a control value for performing an audio output control method for a broadcast system.