JP3197203B2 - Directional sound collector and sound source locator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional sound collecting device applied to a sound source search in low noise equipment such as a low noise wind tunnel, and a sound source searching device using the same.

[0002]

2. Description of the Related Art Conventionally, in sound source search in low-noise equipment such as a low-noise wind tunnel, for example, an array microphone in which a plurality of microphones are arranged in a line is used, and a directivity is provided by processing an output signal thereof. A sex sound collector is used.

[0003] A conventional directional sound collecting device is configured, for example, as shown in FIG. That is, sound waves of a sound source are received by an array microphone 62 in which a plurality of microphones 61 are arranged in a line at equal intervals, and an output signal corresponding to the received sound waves is output from each microphone 61. The plurality of output signals are weighted by a plurality of weighting coefficient circuits 63 by weighting factors Wi (i = 1 to n), and then waveform-synthesized by an adder 64. After the output signal having the synthesized waveform is amplified by the amplifier circuit 65, only the frequency band set in advance by the band-pass filter 66 is extracted, further amplified by the amplifier circuit 67, and output from the output terminal 68. FIG. 6 also shows an amplifier circuit 65, a band-pass filter 66, an amplifier circuit 65, and an output terminal 68 when a plurality of similar directional sound collection devices are installed.

Here, the weight coefficient Wi is generally set to a variable constant of 1 or less in order to reduce the sub-local maximum (side lobe) of directivity. For example, when the weight coefficient Wi is set to 1, the directivity of the conventional directional sound collecting device is expressed by the following equation.

[0005]

(Equation 1) Here, DF is the directivity coefficient, n is the number of microphones, d is the microphone interval, θ is the angle between the array direction of the array microphone and the incident direction of the sound wave, k (= 2πf / c)
Is the wave number of the sound wave, f is the frequency of the sound wave, and c is the speed of sound.

[0006] Uninaru by directional gain of the conventional directional sound collecting apparatus, Ru shown in Figure 7, for example. In FIG. 7, the vertical axis represents directivity gain, and the central axis represents angle θ. (A) shows a case where the microphone interval d × wave number k = 1, that is, the microphone interval d × frequency f is constant, and the directivity becomes sharper as the number n of microphones increases. (B) shows the case where the number n of microphones and the frequency f are kept constant and the microphone interval d is changed.
The directivity becomes sharper as the microphone interval d increases. Such characteristics relating to the main local maximum (main lobe) of the directivity are generally maintained even when the weight coefficient WiＷ1.

As described above, in the conventional directional sound collecting device,
The directivity becomes sharper as the microphone interval d × the number n of microphones, that is, the array length of the array microphones becomes longer.

[0008]

As described above, in the conventional directional sound collecting device, the directivity changes depending on the microphone interval of the microphone array, the number of microphones, and the like, and a sharper directivity is obtained at a constant frequency. Required that the array length of the array microphone be increased. Further, since the ratio between the microphone interval and the wavelength affects the directivity, an array microphone having a longer array length is required for a low-frequency sound wave having a long wavelength. However, when the array length is increased, there is a problem that the directional sound collecting device becomes large and operability is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a directional sound collecting device capable of obtaining sharp directivity using an array microphone having a small array length, and a sound source searching device using the same. Aim.

In order to solve the above-mentioned problems, a directional sound collecting apparatus according to the present invention comprises a plurality of microphones arranged in a line and a first and a second array microphones which are installed to cross each other. First and second synthesizing means for weighting a plurality of output signals respectively output from the first and second array microphones with a predetermined weighting coefficient to synthesize a waveform, and first and second synthesizing means. Multiplying means for multiplying the output signals of the first and second array microphones.
A / D for a plurality of output signals
After converting to a digital signal by the converter,
It is characterized in that weighting and waveform synthesis are performed by a signal processing device .

In this case, after a plurality of output signals respectively output from the first and second array microphones are converted into digital signals by an A / D converter, weighting and waveform synthesis are performed by a digital signal processing device. You may do so.

[0012]

As described above, according to the present invention, first, a plurality of output signals output from the first and second array microphones are weighted and synthesized. The respective directivity patterns corresponding to the two output signals obtained by synthesizing the waveforms are first and second directions in opposite directions.
Is shifted by the crossing angle of the array microphone. Therefore, by multiplying these output signals, a region where the main local maximums of the directivity patterns overlap with each other occurs, so that the final directivity of the directional sound collection device viewed from the multiplied output signals is obtained. In the character pattern, the main maximum is sharpened in the overlap region, and the directivity is enhanced.

Therefore, if an array microphone having the same array length as the conventional one is used, a sharper directivity can be obtained, and even if an array microphone having an array length smaller than the conventional one is used, the directivity equivalent to the conventional one can be obtained. Can be obtained. Furthermore, by appropriately changing the crossing angle of the first and second array microphones, an area where the corresponding directivity patterns overlap each other changes, so that an arbitrary directivity pattern can be obtained.

In the sound source locating apparatus according to the present invention, the direction of the main maximum of the directivity pattern changes according to the rotation angle of the turntable by rotating the first and second array microphones by the turntable. I do. Therefore, the direction of the sound source can be determined from the information on the rotation angle of the turntable when the output signal of the directional sound collection device is maximized.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a directional sound collecting device according to a first embodiment of the present invention. This directional sound collection device is roughly divided into a microphone unit, a filter unit, and an amplification unit.

The microphone section has two sets of array microphones 1 and 2, and the array microphones 1 and 2 are configured to intersect each other at an angle (hereinafter referred to as an intersection angle) 2φ. The array microphone 1 is configured by linearly arranging a plurality of microphones 3 at intervals d, and the array microphone 2 is also configured by arranging the same number of microphones 4 as the microphones 3 in the array microphone 1 linearly at intervals d. ing. Multiple microphones 3, 4
Receives the sound waves, converts them into electric signals, and outputs the electric signals.

The filter section includes a plurality of weight coefficient circuits 5,
6, an adder 7, 8, a multiplier 9, an amplifier circuit 10, and a band-pass filter 11. In the filter unit, output signals output from the plurality of microphones 3 and 4 are weighted by weighting factors Wi (i = 1, 2,..., N) preset by the plurality of weighting factor circuits 5 and 6, After the waveforms are separately synthesized by the adders 7 and 8, respectively,
The multiplier 9 multiplies each other. Further, after the output signal obtained by the multiplication is appropriately amplified by the amplifier circuit 10, only the frequency band set in advance by the band-pass filter 11 is output. The weighting factors Wi in the plurality of weighting factor circuits 5 and 6 are added to adders 7 and 8.
In order to reduce the sub-local maximum (side lobe) of each of the array microphones 1 and 2 viewed from the output of
It is set to the following value.

The amplifying section includes an amplifying circuit 12 and an output terminal 1
3 and the band-pass filter 1
1 is appropriately amplified and output from the output terminal 13. A display device, a recording device, or the like is connected to the output terminal 13, for example. FIG. 1 also shows an amplifier circuit 10, a bandpass filter 11, an amplifier circuit 12, and an output terminal 13 when a plurality of similar directional sound collection devices are installed.

Hereinafter, the operation of this embodiment will be described. Now, a sound wave is emitted from a sound source (not shown), and a bisector 14 having an intersection angle of 2φ between the array microphones 1 and 2.
It is assumed that light is incident at an angle θ with respect to. Here, the directivity of each of the array microphones 1 and 2 viewed from the outputs of the adders 7 and 8 is expressed by the following equation, for example, when the weight coefficient Wi = 1.

[0021]

(Equation 2) Where DF is the directivity coefficient, n is the array microphone 1,
2, the number of microphones, d is the microphone interval, and k (=
2πf / c) is the wave number of the sound wave, f is the frequency of the sound wave, and c is the speed of sound.

[0022] In this case, by each of the directional gain of A L'<br/> Lee microphones 1 and 2 as seen at the output of the adder 7 and 8, Ru shown in FIG. 2, for example Uninaru. FIG. 2 shows the intersection angle 2φ = 2
4 ° (φ = 12 °), wave number k × microphone interval d =
1, and Ri Oh <br/> in the case a microphone number n = 16, the vertical axis represents the directional gain, the central axis represents the angle theta. 2, the solid line represents the directional gain of the array microphone 1 as viewed from the output of the adder 7, and the dotted line represents the adder 8
5 shows the directional gain of the array microphone 2 viewed from the output of FIG. As shown in FIG. 2, each directivity pattern is shifted in the opposite direction by an angle φ, and the area A where the main maximum of each directivity pattern overlaps with each other.
Has occurred.

As described above, the output signals of the adders 7 and 8 are multiplied by each other in the multiplier 9.
Therefore, the final directivity pattern as the directivity sound collecting device viewed from the output of the multiplier 9 has a sharp main maximum corresponding to the region A, and the directivity is enhanced.

As described above, two array microphones are provided so as to cross each other, and after predetermined processing is performed on each output signal and then multiplied by each other, a directivity pattern finally obtained is given to each array microphone. The main local maximum is sharpened corresponding to the areas of the corresponding directivity patterns that overlap each other, and the directivity is enhanced. Therefore, sharper directivity can be obtained as compared with the case where only one array microphone is used as in the related art. Also, by appropriately changing the crossing angle of the two array microphones, the area where the directivity patterns corresponding to each array microphone overlap with each other also changes, and it is possible to finally obtain an arbitrary directivity pattern. Become.

FIG. 3 is for comparing each of the directional gain of the present embodiment and the conventional directional sound collector, the vertical axis represents the directional gain, the central axis represents the angle θ I have. The dotted line indicates the number of microphones n =
16, φ = 12 °, the solid line represents the case where the number of microphones is n = 32 in the conventional directional sound collecting device, and the measurement is performed with the wave number k × microphone interval d = 1. . However, as described above, the angle θ in the present embodiment refers to the bisector 14 in FIG.
The angle θ in the conventional directional sound collecting device is the angle between the array direction and the incident direction of the sound wave.

As shown in FIG. 3, this embodiment uses half the number of microphones of the conventional directional sound collecting device.
Almost the same directivity as the conventional one is obtained. That is, in this example, it can be seen that in the present embodiment, an array microphone having an array length half that of the related art can obtain almost the same directivity as the related art.

As described above, in this embodiment, even when an array microphone having an array length smaller than that of the conventional directional sound collecting device is used, it is possible to obtain the same directivity as the conventional one. If an array microphone having the same array length as that of the related art is used, it is possible to obtain sharper directivity than before.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
It is a block diagram showing the composition of the directional sound collection device concerning an embodiment. In the present embodiment, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and differences from the first embodiment will be mainly described.

In this embodiment, the array microphones 1 and 2
(A / D) converters 21 and 22, digital signal processors (DSP) 23 and 24, D / A (digital / analog) A converter 25 is further provided. Here, the DSPs 23 and 24 correspond to FIG.
And a plurality of output signals output from the A / D converters 21 and 22 by a predetermined weighting factor. Weighting is performed to synthesize a waveform, and only a preset frequency band is multiplied by a multiplier 9.
Output to At this time, the amplification processing corresponding to both or one of the amplification circuits 10 and 12 in FIG. 1 may be performed in the middle of the above-described processing.

In this embodiment, a plurality of output signals output from the array microphones 1 and 2 are first converted into digital signals by A / D converters 21 and 22, respectively.
Next, each of the DSPs 23 and 24 is weighted by a predetermined weighting coefficient and then subjected to waveform synthesis to extract only a predetermined frequency band. Thereafter, the two output signals are multiplied by each other by a multiplier 5, converted into an analog signal by a D / A converter 25, and output from an output terminal 13.
The output signal obtained by the multiplication without the D / A converter 25 may be output as a digital signal.

(Third Embodiment) FIG. 5 is a block diagram showing a configuration of a sound source searching device according to a third embodiment of the present invention. This sound source locator has X
Type array microphone 31 (hereinafter referred to as the directivity according to the present invention)
The array microphone of the sound collector is replaced with an X-type array microphone.
) , A digital signal processor 32, a turntable 33, a controller 34, and a personal computer 3.
5 and a monitor 36.

Here, the X-type array microphone 31 is
It has the array microphones 1 and 2 shown in FIG. 1, generates a plurality of output signals of two systems according to received sound waves, and outputs them to the digital signal processing device 32. The X-type array microphone 31 is installed on a turntable 33, and rotates when the turntable 33 is driven, and changes an angle θ between the bisector 14 in FIG. Let it. The digital signal processing device 32 has the A / D converters 21 and 22 and the DSPs 23 and 24 shown in FIG.

In this sound source searching apparatus, a plurality of output signals of two systems output from the X-type array microphone 31 are converted into digital signals by A / D converters 21 and 22 in a digital signal processor 32. DSP
After performing processes such as weighting of output signals, waveform synthesis, and frequency band selection in 23 and 24, the signals are multiplied by a multiplier 9 and output to the personal computer 35.

On the other hand, the personal computer 35
A command signal for controlling the rotation angle of the array microphone 31 is generated and output to the controller 34. At this time, for example, the personal computer 35 may control the rotation angle of the turntable 33 so that the output signal of the digital signal processing device 32 is maximized.

The controller 34 outputs a drive signal corresponding to the command signal to the turntable 3. The turntable 33 is driven by the drive signal to rotate the X-type array microphone 31, and determines the rotation angle at this time. 34
Is output to the personal computer 35 via.

The output signal of the digital signal processor 32 and the information on the rotation angle output from the controller are input to the personal computer 35. Here, when the X-type array microphone 31 rotates, the direction of the main local maximum of the directivity corresponding to the output signal changes according to the rotation direction of the turntable 33. The personal computer 35 analyzes the output signal and the information on the rotation angle using the sound source analysis software, and calculates the direction and the like from the information on the rotation angle when the output signal becomes maximum, and displays the result on the monitor 36. I do.

[0037]

As described above, according to the present invention, there is provided a directional sound collecting device capable of obtaining sharp directivity using an array microphone having a small array length, and a sound source searching device using the same.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a directional sound collection device according to a first embodiment of the present invention.

[Figure 2] shows to view a directional gain of the embodiment

[Figure 3] shows to view a directional gain of the embodiment and the conventional directional sound collector

FIG. 4 is a block diagram showing a configuration of a directional sound collecting device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a sound source detection device according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a conventional directional sound collecting device.

FIG. 7 is a block diagram showing a directional gain of a conventional directional sound collecting device.

[Explanation of symbols]

 1, 2, array microphone 3, 4, microphone 5, 6, weight coefficient circuit 7, 8, adder 9, multiplier 10, amplifier circuit 11, bandpass filter 12, amplifier circuit 13, output terminal 14, bisecting Lines 21, 22 A / D converters 23, 24 Digital signal processing device 25 D / A converter 31 X-type array microphone 32 Digital signal processing device 33 Turntable 34 Controller 35 Personal computer 36 Monitor 61 ... Microphone 62 ... Array microphone 63 ... Weight coefficient circuit 64 ... Adder 65 ... Amplification circuit 66 ... Band pass filter 67 ... Amplification circuit 68 ... Output terminal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04R 3/00 320 G01H 3/00 G01S 3/809 H04R 1/40 320 H04R 5/027

Claims (3)

(57) [Claims] 1. A first and a second array microphones, each of which has a plurality of microphones arranged in a line, and which are installed so as to cross each other, and output from the first and the second array microphones, respectively. comprising first and second combining means for waveform synthesis a plurality of output signals weighted by predetermined weighting coefficients and multiplying means for multiplying an output signal of said first and second combining means, said first And the second combining means includes the first and second combining means.
Output from each array microphone
Force signal was converted to digital signal by A / D converter
Thereafter, the weighting and the weighting are performed by a digital signal processing device.
A directional sound collector that performs the waveform synthesis . 2. A first and a second array microphones, each of which has a plurality of microphones arranged in a line, and which are installed crossing each other, and output from the first and the second array microphones, respectively. First and second combining means for weighting a plurality of output signals by a predetermined weighting coefficient to synthesize a waveform; multiplying means for multiplying output signals of the first and second combining means; A turntable for rotating the array microphone of No. 2; control means for controlling the rotation angle of the turntable; and determination for determining the direction of the sound source based on an output signal of the multiplication means and information on the rotation angle of the turntable. Means for locating a sound source. 3. The method according to claim 1, wherein the first and second synthesizing means include:
Output from the first and second array microphones respectively.
A / D converter converts a plurality of output signals
After the conversion, the digital signal processor
And performing the waveform synthesis.
Item 2. A sound source detection device according to Item 2 .