JP6763332B2 - Sound collectors, programs and methods - Google Patents

Description

The present invention relates to a sound collecting device, a program and a method, and can be applied to, for example, a case where only a sound in a specific area is emphasized and a sound in another area is suppressed.

Conventionally, a beam former using a microphone array is used as a technique for emphasizing sounds existing in a specific direction (voice and sound; hereinafter, sound and sound are sometimes collectively referred to as sound) and suppressing other sounds. There is. The beam former is a technique for forming directivity and blind spots by utilizing the time difference between signals arriving at each microphone (see Non-Patent Document 1 and Non-Patent Document 2).

However, if the directivity of the beam former is simply directed to an area for sound collection purposes (hereinafter referred to as "target area"), if there is a noise source around the target area, it exists in the target area. There is a problem that not only the sound source (hereinafter referred to as "target area sound") but also the noise source existing outside the target area (hereinafter referred to as "non-purpose area sound") is picked up at the same time.

To solve this problem, a conventional method has been proposed in which directivity is crossed from different directions toward a target area by using a plurality of microphone arrays, and sound in the target area is picked up (Patent Document 1). In the method described in Patent Document 1, the target area is extracted by simultaneously processing the beamformer output of each microphone array.

FIG. 6 is an explanatory diagram showing an example of sound collection processing using a plurality of conventional microphone arrays.

FIG. 6 shows an example in which the directivity of the _two microphone arrays MA (MA ₁ and MA ₂ ) is directed toward the target area.

FIG. 6A shows the positional relationship between each microphone array MA and the sound source of the target area sound when the directivity of the _two microphone arrays MA ₁ and MA ₂ is directed toward the target area. Further, FIG. 6A also illustrates the directivity (directivity of the beam former) D1 and D2 corresponding to the microphone arrays MA ₁ and MA ₂ . Further, in the example of FIG. 6A, a sound source of the non-purpose area sound exists around the sound source of the target area. Therefore, in the state of FIG. 6A, both the beamformer outputs of the microphone arrays MA ₁ and MA ₂ are not only in the target area sound by the sound source in the target area but also in the non-purpose area in the same directivity direction. Non-purpose area sound from the sound source is included.

6 (b) and 6 (c) show the frequency components of the beamformer outputs of the _two microphone arrays MA ₁ and MA ₂ , respectively. Assuming the sparsity of speech, as shown in FIGS. 6 (b) and 6 (c), one frequency component includes only one sound source (target area sound or non-target area sound). Since the target area is included in the directivity of all the microphone arrays, the frequency components of the target area sound are included in all the beam former outputs in the same proportion and with the same distribution. In comparison, the frequency component of the non-purpose area sound is different for each beamformer output. From these characteristics, the frequency component commonly included in each beamformer output can be estimated to be a component of the target area sound, and based on this, the conventional target area sound described in Patent Document 1 and the like can be estimated. The sound collection method of is realized.

FIG. 7 is a block diagram showing a functional configuration of the sound collecting device 10 to which the conventional sound collecting method is applied.

The conventional sound collecting device 10 shown in FIG. 6 includes a data input unit 2, a frequency domain conversion unit 3, a directivity forming unit 4, a propagation delay difference correction unit 5, a power correction unit 6, a first subtraction unit 7, and a first subtraction unit 7. It has a subtraction unit 8 of 2.

The captured signals from the microphone arrays MA ₁ and MA ₂ are each converted from an analog signal to a digital signal (data) in the data input unit 2 and converted from a time domain to a frequency domain in the frequency domain conversion unit 3, respectively. Groups X ₁ and X ₂ are obtained. Then, a beam former having directivity such as the directivity D1 and the directivity D2 of FIG. _6A is applied to the directivity forming unit 4, and the beamformer output signals X _ma1 (f) and X _ma2 (f) are _generated. can get. Then, the propagation delay difference correction unit 5 delays one of the beam former output signals X _ma1 (f) and X _ma2 (f) based on the distance (known information) between each microphone array and the target area to _adjust the timing. together, the delay correction signal X _'ma1 (f) and X' _ma2 (f) is obtained.

In the power correction unit 6, in addition to the amplitude difference due to the distance between each microphone array and the target area, the amplitude correction coefficient α _ma1 (alpha) is calculated by the equation (1) in order to adapt to the direction of the speaker in the target area. To do. The operator mode _f (A (f)) in the equation (1) is an operator that obtains the most frequently occurring value (mode) of the function values A (f) whose values change depending on the variable f. .. Further, instead of the mode value, the median value may be used as in Eq. (2). The operator median _f (A (f)) in the equation (2) is an operator that obtains the median value of the function value A (f) whose value changes depending on the variable f.

Then, in the first subtracting unit 7, 'delay correction signal X according _ma1 from (f) to the microphone array MA ₂ obtained by correcting the amplitude by the amplitude correction coefficient alpha _{ma1' ma2} delay correction signal X according to the microphone array MA ₁ (f ) by spectral subtraction to both beamformer erased object area sound components overlapping in the output, the delay correction signal X _{'ma1 (f)} non-target area sound components contained in the N of the microphone array MA _{1 ma1} (f) is extracted. Equation (3) is a calculation equation that generally follows this way of thinking.
_{N ma1 = X 'ma1 -α ma1} · X' ma2 ... (3)

Then, in the second subtracting unit 8, by spectral subtraction of the non-target area sound component _{N ma1} (f) from the delay correction signal X _'ma1 according to the microphone array MA ₁ (f), sound object area _{Y ma1} (f ) Is extracted. Equation (4) is a calculation equation that generally follows this idea (β _ma1 (beta) in equation (4) is a coefficient that takes a constant value that determines the removal intensity of non-purpose area sound). ..
Y _ma1 = _X'ma1- β _ma1 · N _ma1 ... (4)

As described above, in the sound collecting device to which the conventional sound collecting method is applied, even if the non-purpose area sound source exists around the target area, only the target area sound can be picked up.

Japanese Unexamined Patent Publication No. 2014-722708

Tadashi Asano, "Sound Array Signal Processing-Sound Source Localization, Tracking and Separation", Acoustical Society of Japan, Corona Publishing Co., Ltd., February 25, 2011 Takashi Yato, Makoto Morito, Kei Yamada, Tetsuji Ogawa, "Sound Source Separation Technology by Square Microphone Array (<Special Feature> Efforts to Practical Use of Speech Recognition Technology)", Information Processing Society of Japan, Information Processing 51 (11) , Pp. 1410-1416.2010

However, in the conventional sound collection method, in order to adapt to the amplitude difference due to the distance between each microphone array MA and the target area and the orientation of the speaker in the target area, the mode calculation as in Eq. (1) is performed. Or, the operation of the median value as in Eq. (2) is required. To calculate the mode, it is necessary to create a frequency distribution (also called a histogram), and to create a frequency distribution, it is necessary to empirically determine the fineness (resolution) of the class in addition to many comparison operations. There is. In addition, in order to calculate the median, it is necessary to sort the given data in order of magnitude, and it is necessary to perform a large number of comparison operations.

Further, in the conventional sound collection method, in order to calculate the amplitude correction coefficient α _ma1 for adapting to the amplitude difference due to the distance between each microphone array MA and the target area and the orientation of the speaker in the target area. , The number of microphone arrays must be two. Therefore, for example, when the target area is set three-dimensionally as shown in FIG. 8, two microphone arrays MA ₁ and MA ₂ are set as a flat microphone array having three or more microphones (FIG. 8 shows four microphones). as it has) shows an example of a planar microphone array using 1 ₁ to 1 _4, so that the two microphone arrays MA _1, the directivity of the MA ₂ intersect in the object area (e.g., a central position near the destination area) Must be installed carefully.

In other words, the conventional sound collection method has a problem that the amount of calculation is large, a problem that parameters must be determined empirically in advance, and a problem that the number and arrangement of each microphone and microphone array are limited. ..

Therefore, with less computation, sound collectors, programs and methods that emphasize only the target area sound, without being limited by the number and placement of each microphone and microphone array, without parameters that must be determined in advance. It is desired.

The first sound collecting device of the present invention is (1) when the beam former forms directivity in the target area sound direction for each of the input signals obtained by converting the captured signals output by the plurality of microphone arrays into the frequency domain. The directivity gain calculation means for acquiring the directivity gain of the above, (2) the area enhancement gain calculation means for acquiring the area enhancement gain for emphasizing the target area sound based on the directivity gain of each of the microphone arrays, and (3). ) It is characterized by having a target area sound acquisition means for acquiring a target area emphasis signal that emphasizes the target area sound based on the input signal of the microphone array and the area emphasis gain acquired by the area emphasis gain calculation means. To do.

The second sound collection program of the present invention uses a beamformer to direct the computer in the direction of the sound in the target area for each of the input signals obtained by converting the captured signals output by the plurality of microphone arrays into the frequency region. A directivity gain calculation means for acquiring the directivity gain at the time of formation, and (2) an area enhancement gain calculation means for acquiring an area enhancement gain for emphasizing the target area sound based on the directivity gain of each of the microphone arrays. , (3) Based on the input signal of the microphone array and the area enhancement gain acquired by the area enhancement gain calculation means, the target area sound is functioned as a target area sound acquisition means for acquiring the target area emphasis signal that emphasizes the target area sound. It is characterized by.

A third aspect of the present invention includes (1) directional gain calculating means, area emphasis gain calculating means, and target area sound acquiring means in a sound collecting method, and (2) the directional gain calculating means includes a plurality of microphones. For each of the input signals obtained by converting the captured signal output by the array into the frequency region, the directional gain at the time of forming the directivity in the target area sound direction by the beam former is acquired, and (3) the area emphasis gain calculation means. Acquires an area enhancement gain that emphasizes the target area sound based on the directional gain of each of the microphone arrays, and (4) the target area sound acquisition means obtains the input signal of the microphone array and the area enhancement gain. Based on the area emphasis gain acquired by the calculation means, the target area emphasis signal that emphasizes the target area sound is acquired.

According to the present invention, it is possible to emphasize only the target area sound without being limited by the number and arrangement of the microphone and the microphone array, respectively, with less calculation amount and without parameters that must be determined in advance.

It is a block diagram which showed the functional structure of the sound collecting apparatus which concerns on 1st, 3rd, 4th Embodiment. It is explanatory drawing (image figure) which showed the outline (technical idea) of the sound collecting process in the sound collecting apparatus which concerns on 1st Embodiment. It is explanatory drawing which showed the configuration example of the microphone array which concerns on 1st Embodiment. It is a block diagram which showed the internal structure of the directivity gain calculation part which concerns on 1st Embodiment. It is a block diagram which showed the functional structure of the sound collecting apparatus which concerns on 2nd Embodiment. It is explanatory drawing which showed the example of the conventional sound collection method. It is a block diagram which showed the functional structure of the conventional sound collecting apparatus. It is explanatory drawing which showed the structural example of the plane microphone array used in the conventional sound collecting apparatus.

(A) First Embodiment Hereinafter, the first embodiment of the sound collecting device, the program and the method according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of First Embodiment FIG. 1 is a block diagram showing a functional configuration of the sound collecting device 100 of this embodiment. In FIG. 1, the reference numerals in parentheses are the reference numerals used in the third and fourth embodiments described later.

The sound collecting device 100 uses the acoustic signals supplied from the _M microphone arrays MA (MA _{1 to} MA _M ) to perform the target area sound collecting process for collecting the target area sound from the sound source in the target area. ..

Each microphone array MA is arranged in a space where the target area exists so that the target area can be directed.

The microphone arrays MA _{1 to} MA _M in FIG. 1 are shown so that the microphones 1 are arranged linearly at equal intervals, but the present invention is not limited to this, and any arrangement may be used as long as the beam former can be executed. The number of microphones 1 constituting each microphone array MA is not limited except that it is at least two or more, and may be different for each microphone array MA or may be the same for all microphone array MAs. The following denote the number of the microphone 1 for any i th microphone array MA _i and L _i. Accordingly, the number of the microphone 1 of the microphone array _MA 1 to MA _M becomes _L 1 ~L _M respectively.

Further, the arrangement of the microphones 1 constituting each microphone array MA is not limited except that the target area can be directed. For example, in the first embodiment, a linear microphone array in which a plurality of microphones 1 are arranged linearly may be used. However, a flat microphone array in which a plurality of microphones 1 are arranged on a plane may be used, or a plurality of microphones 1 may be arranged in a crystal shape (regular polygonal arrangement, rectangular arrangement, regular polyhedron arrangement, regular polygonal pillar arrangement, rectangular body arrangement, etc.). A crystal type microphone array or the like may be used. Further, the arrangement of the microphones 1 may be different for each microphone array MA, and may be the same for all the microphone arrays MA.

Next, an outline (technical idea) of the sound collection process (method of emphasizing the target area sound; the sound collection method of this embodiment) in the sound collection device 100 will be described with reference to FIG.

First, reference is made to FIGS. 2 (a-1) to 2 (a-3). FIG. 2A-1 shows a frequency component (hereinafter, referred to as “amplitude of MA ₁ ”) related to a captured signal captured by any of the microphones 1 constituting the microphone array MA ₁ . Further, in FIG. 2 (a-3), shows the beamformer output of the microphone array MA ₁ frequency components (BF Output) (hereinafter, also referred to as "amplitude BF1"). Further, FIG. 2A-2 shows a value obtained by dividing the “amplitude of BF 1” by the “amplitude of MA ₁ ” (hereinafter, referred to as “directivity gain of MA ₁ ”).

Next, reference is made to FIGS. 2 (b-1) to 2 (b-3). FIG. 2B-1 shows a frequency component (hereinafter, referred to as “amplitude of MA ₂ ”) related to a captured signal captured by any of the microphones 1 constituting the microphone array MA ₂ . Further, FIG. 2 (b-3) shows a frequency component (hereinafter, also referred to as “amplitude of BF 2”) of the beam former output (BF output) related to the microphone array MA ₂ . Further, FIG. 2 (b-2) shows a value obtained by dividing the “amplitude of BF 2” by the “amplitude of MA ₂ ” (hereinafter, referred to as “directivity gain of MA ₂ ”).

Next, reference is made to FIGS. 2 (c-1) to 2 (c-3). FIG. 2 (c-1) shows the “amplitude of MA ₁ ” as in FIG. 2 (a-1). FIG. 2 (c-2) is a product of “MA ₁ directional gain” and “MA 2 directional gain” (hereinafter referred to as “area emphasis gain”). Figure 2 (c-3) shows a destination area sound extracted using the "directional gain MA _1" from the "amplitude MA _1".

The "directivity gain of MA ₁ " and the "directivity gain of MA ₂ " may or may not need to be calculated after the beamformer depending on the method of the beamformer. For example, in the beam former by the delay sum method (see Non-Patent Document 1), the amplitude after the beam former can be obtained, so that the directivity gain needs to be obtained by division. Further, for example, in Reference to Non-Patent Document 2 relating to a conventional beam former by spectrum subtraction, it is described that the amplitude after the beam former is obtained, but in reality, the directivity gain can be obtained by transforming the equation. .. Further, for example, the method described in JP-A-2007-318528 (hereinafter referred to as "Reference 1") obtains the amplitude after the beam former by obtaining the directivity gain and multiplying it by the frequency component of the captured signal. Since it is a method, the directional gain can be obtained directly.

In the "directivity gain of MA ₁ " and "directional gain of MA ₂ " obtained as described above, 0 and 1 are staggered for the non-purpose area sound, but the target area sound It is always 1 for the frequency component. Therefore, by multiplying the two directional gains, a gain that emphasizes only the frequency component of the target area sound can be obtained as in the “area emphasis gain” of FIG. 2 (c-2). In other words, "MA ₁ directional gain" and "MA ₂ directional gain" take either 0 or 1 value (value close to 0 or 1) for the non-purpose area sound component. However, the frequency components of the target area sound are always 1 (values close to 1).

In "MA ₁ directional gain" and "MA ₂ directional gain", the directional gain for the non-purpose area sound that can be suppressed by each is not always 0, but it is always a small value (for example,). Since it is a value close to 0) and the directivity gain for the target area sound is always 1 or less, the gain for the non-target area sound in the “area emphasis gain” is always small.

Therefore, in the sound collecting device 100 of this embodiment, the target area is used by using the area enhancement gain calculated by multiplying the directivity gain calculated for each microphone array MA over all the microphone arrays MA for each frequency component. Sound shall be extracted. As a result, in the sound collecting device 100 of this embodiment, it is not necessary to obtain the mode value and the median value as in the prior art, so that it is possible to realize a process of emphasizing the target area sound with a relatively small amount of calculation. it can.

By the way, as for the configuration of each microphone array MA, for example, as shown in FIG. 3, three microphone arrays MA _{1 to} MA ₃ are prepared, and two microphone arrays MA ₁ and MA ₃ have two microphones 1 ₁ , 1 and ₂ . The linear array may be arranged in the horizontal direction (horizontal direction in FIG. 3), and the microphone array MA ₂ may be a linear array in which _two microphones are arranged in the vertical direction (vertical direction in FIG. 3).

When each microphone array MA is arranged as shown in FIG. 3, the sound collecting device 100 calculates the gain of the beam former from the beam former that collects the sound in the target area direction in each microphone array MA, and three for each frequency component. By multiplying all the gains of the beam former, the target area sound can be extracted. In FIG. 3, the directivity (central surface of directivity) of the microphone arrays MA _{1 to} MA ₃ is shown as D11 to D13. That is, the central surfaces of the directivities D11 to D13 of the microphone arrays MA _{1 to} MA ₃ are the planes shown in the directivity D11 to D13 in FIG. 3, and the target area determined by the sound collecting device 100 of this embodiment is directed. It is around the position where the central planes of sexes D11 to D13 intersect.

Next, the internal configuration of the sound collecting device 100 will be described with reference to FIG.

As shown in FIG. 1, the sound collecting device 100 according to the first embodiment includes a data input unit 102, a frequency domain conversion unit 103, a directivity gain calculation unit 104, an area emphasis gain calculation unit 105, and a target area sound extraction. It has a part 106. Details of each component inside the sound collecting device 100 will be described later.

In the sound collecting device 100, a computer having a processor, a memory, or the like may execute a program (including a sound collecting program according to the embodiment) for the processing configuration after being converted into a digital signal. Even so, functionally, it can be represented in FIG.

Next, the internal configuration of the directivity gain calculation unit 104 will be described with reference to FIG.

FIG. 4 is a block diagram showing a functional configuration inside the directivity gain calculation unit 104.

Directional gain calculating unit 104 includes a noise estimator ₁₁₁ 1 - 111 _M and spectral subtraction gain calculating unit ₁₁₂ 1 to 112 _M respectively microphone array _MA 1 to MA _M. Details of each component inside the directivity gain calculation unit 104 will be described later.

(A-2) Operation of the First Embodiment Next, the operation of the sound collecting device 100 of the first embodiment having the above configuration (sound collecting method of this embodiment) will be described.

The data input unit 102 converts the acoustic signal captured by the microphone arrays MA1 _{1 to} MA _M from an analog signal to a digital signal (data) for each microphone 1. Then, the data input unit 102 gives the obtained captured signal group x ₁ (t) to x _M (t) to the frequency domain conversion unit 103. i th acquisition signal group _x i (t) is a vector consisting of (5) as shown in formula, _{L i} number of captured signals _{x i, 1 (t) ~x} i, Li (t) ..
x _i (t) = [x _{i, 1} (t), ..., x _{i, Li} (t)] ... (5)

The frequency domain conversion unit 103 converts the data input from the microphone arrays MA _{1 to} MA _M from the time domain to the frequency domain for each microphone. Frequency domain transform section 103, a capture signal group _X 1 in the frequency domain obtained _{(f) ~X M (f)} , giving the directional gain calculating unit 104 and the destination area sound extraction unit 106. i-th frequency domain acquired signal group _X i of (f) is composed of (6) as shown in formula, _{L i} number of captured signals _X i, 1 _{(f) to X i,} Li (f) It is a vector. For the conversion in the frequency domain transforming unit 103, a fast Fourier transform (FFT), a wavelet transform, a filter bank, or the like can be used, but the FFT is the most preferable. Here, the frequency domain transforming unit 103 may use various window functions such as a humming window when performing the FFT.
X _i (f) = [X _{i, 1} (f), ..., X _{i, Li} (f)] ... (6)

Directional gain calculating unit 104, for each microphone array MA, capture signal group _X 1 (f) _~X based on M (f) applying beamformer directional gain _G 1 in the frequency domain (f) ~G Calculate _M (f). The resulting directivity gain _{G 1 (f) ~G M (} f) is given to the area enhancement gain calculation unit 105. Directional gain, from the captured signal group _X 1 belonging to one of the microphone array (f), obtained by one for each frequency _(i.e., unlike _{X i (f), G i} (f) is a scalar) .. In the directivity gain calculation unit 104, any method can be used as the beam former method, but a method capable of forming a sharp directivity represented by the method by spectrum subtraction described in Non-Patent Document 2 is preferable. Used. In the directional gain calculation unit 104 of this embodiment, as shown in FIG. 3, the target area is located in front of all the microphones 1, and all the microphone arrays MA have two microphones 1 ₁ . 1 ₂ is composed of, any of the microphone array MA calculates a directivity gain in the same manner, the directional gain is described as being calculated by the method based on spectral subtraction.

Next, the internal processing of the directivity gain calculation unit 104 will be described with reference to FIG.

Since the same processing is performed for all the microphone arrays MA, only the operations of the noise estimation unit 111 _i and the spectrum subtraction gain calculation unit 112 _i corresponding to the i-th microphone array MA _i will be described here.

As shown in Eq. (7), the noise estimation unit 111 _i suppresses the sound source (target area sound) in the front direction (target area direction) by subtracting the other captured signal from one captured signal. Estimate noise (non-purpose area sound). As shown in Eq. (8), the spectrum subtraction gain calculation unit 112 _i reduces the amplitude ratio of the non-objective area sound and the captured signal from 1 (spectral subtraction) to obtain the directivity gain G _i (f). calculate. In equation (8), β (f) (beta) is used for each frequency component that corrects the estimated amplitude of the non-purpose area sound and adjusts the strength of spectrum subtraction (removal strength of the non-purpose area sound). It is a fixed constant coefficient. Further, in the equation (8), G _min is a constant value that determines the minimum value (also referred to as the maximum suppression amount) of the directivity gain. By multiplying both sides of Eq. (8) by the absolute values of X _{i and 1} (f), Eq. (9) is obtained, and the amplitude of the beamformer output by spectral subtraction can be obtained. When obtaining the beamformer output, the equation (9) is generally used, but in the present embodiment, the directivity gain is directly calculated by using the equation (8).

Area enhancement gain calculation unit 105 calculates a (10) as in equation directivity gain for each frequency component _{G 1 (f) ~G M (} f) by multiplying the in area emphasis gain H (f). The obtained area emphasis gain H (f) is given to the target area sound extraction unit 106.
_{H (f) = G 1 (} f) · G 2 (f) · ... · G M (f) ... (10)

The target area sound extraction unit 106 multiplies the captured signal group X ₁ (f) to X _M (f) or a signal in which they are integrated by the area emphasis gain H (f) to obtain the target area emphasis signal Y ( f) is calculated. The obtained target area emphasis signal Y (f) is given to the next stage. The signal to which the area emphasis gain H (f) is multiplied is arbitrary, and may be the first X _{1, 1} (f), may be a captured signal related to the microphone 1 closest to the target area, or may be the closest target area. A delay sum beam former may be applied to the captured signal group of the nearby microphone array MA to obtain a signal in which the target area sound is slightly emphasized.

(A-3) Effect of First Embodiment According to the first embodiment, the following effects can be obtained.

According to the first embodiment, the target area sound is extracted using the area enhancement gain calculated by multiplying the directivity gain calculated for each microphone array MA over all the microphone array MAs for each frequency component. Therefore, the target area is surrounded by the non-purpose area sound source without being limited by the number and arrangement of the microphone 1 and the microphone array MA, respectively, with a relatively small amount of calculation and no parameters that must be determined in advance. Even in the situation where there is, only the target area sound can be emphasized.

(B) Second Embodiment Hereinafter, the second embodiment of the sound collecting device, the program and the method according to the present invention will be described in detail with reference to the drawings.

(B-1) Configuration of Second Embodiment FIG. 5 is a block diagram showing a functional configuration of the sound collecting device 200 of the second embodiment, and the same portion or symmetrical portion as that of FIG. 1 described above. , Same code or symmetric code. Hereinafter, only the difference between the sound collecting device 100A of the second embodiment and the sound collecting device 100A of the first embodiment will be described.

In the description of the first embodiment (sound collecting device 100), the distance between each microphone array MA and the target area (hereinafter, referred to as “array sound collecting distance”) is not mentioned at all. For example, in the first embodiment, in a somewhat small environment where the array sound collection distance is at most about 150 cm, the sound collection device 100 may ignore the array sound collection distance and perform signal processing. The quality of the output signal does not deteriorate significantly. However, when the difference in the array sound collection distance (for example, the difference between the array sound collection distance of the microphone array MA _{1 and} the array sound collection distance of the microphone array MA ₂ ) is 300 cm or more, the target area is set in each microphone array MA. Since the time difference between the arrival of sounds is too large, the timing of emphasizing the target area sound direction may be different between the microphone arrays MA, and the area sound may not be extracted correctly.

Therefore, in the sound collecting device 200 of the second embodiment, assuming that the difference between the array sound collecting distance of each microphone array MA or the array sound collecting distance between the microphone arrays MA is known, the directivity gain is delayed. Adjust the timing.

As shown in FIG. 5, the sound collecting device 200 differs from the first embodiment in that the area emphasis gain calculation unit 105 is replaced with the area emphasis gain calculation unit 105 and the propagation delay correction unit 207 is further added. There is.

(B-2) Operation of the Second Embodiment Next, the operation of the sound collecting device 200 of the second embodiment having the above configuration (sound collecting method of this embodiment) will be described.

The operation of the sound collecting device 200 according to the second embodiment is the same as the operation of the sound collecting device 100 according to the first embodiment except for the propagation delay correction unit 207 and the area emphasis gain calculation unit 205. The operation description of the element is omitted.

The propagation delay correction unit 207 has the smallest array sound collection distance (closest to the target area) based on the difference in the array sound collection distance for each microphone array MA or the array sound collection distance between each microphone array confirmed in advance. ) delays the directional gain _G 1 derived from the microphone array MA non microphone array _{MA (f) ~G M (f} ). The resulting delayed directional gain _{G '1 (f) ~G'} M (f) is given to the area enhancement gain calculation unit 205. That is, the delay directional gain _{G '1 (f) ~G'} M (f) corrects the timing shift based on the array sound collection distance for all of the microphone array MA (delay), is synchronized to the timing-oriented It becomes a directivity gain.

Area enhancement gain calculation unit 205 calculates (11) a delay directivity gain for each frequency component _{G '1 (f) ~G'} M (f) a multiplying allowed by area emphasis gain H (f) as equation .. The area emphasis gain calculation unit 205 gives the obtained area emphasis gain H (f) to the target area sound extraction unit 106.
_{H (f) = G '1} (f) · G' 2 (f) · ... · G 'M (f) ... (11)

(B-3) Effect of Second Embodiment According to the second embodiment, the following effects can be obtained in addition to the effect of the first embodiment.

In the sound collecting device 200 of the second embodiment, the situation is such that the difference in the array sound collecting distance between the microphone arrays MA exceeds 300 cm in a large-scale environment, and the target area is surrounded by the non-purpose area sound source. However, only the target area sound can be emphasized.

(C) Third Embodiment Hereinafter, the third embodiment of the sound collecting device, the program and the method according to the present invention will be described in detail with reference to the drawings.

(C-1) Configuration of Third Embodiment The sound collecting device 300 of the third embodiment can also be shown with reference to FIG. 1 described above.

In the following, only the differences between the third embodiment and the first and second embodiments will be described.

In the sound collecting devices 100 and 200 of the first and second embodiments, the area emphasis gain was calculated by multiplying the directional gains derived from all the microphone arrays MA (MA _{1 to} MA _M ). However, since this method corresponds to applying a filter for suppressing noise to the signal M times, the output signals of the sound collecting devices 100 and 200 of the first and second embodiments may be distorted.

Therefore, in the sound collecting device 300 of the third embodiment, the distortion is obtained by multiplying the M directional gains and then taking the M root after multiplying the M directional gains, instead of simply multiplying the M directional gains. To avoid.

As shown in FIG. 1, the sound collecting device 300 of the third embodiment is different from the sound collecting device 100 of the first embodiment in that the area emphasis gain calculation unit 105 is replaced with the area emphasis gain calculation unit 305. ing.

(C-2) Operation of Third Embodiment Next, the operation of the sound collecting device 300 of the third embodiment having the above configuration (sound collecting method of this embodiment) will be described.

Since the operation of the sound collecting device 300 according to the third embodiment is the same as the operation of the sound collecting device 100 according to the first embodiment except for the area emphasis gain calculation unit 305, the operation description of other elements will be described. Omit.

Area enhancement gain calculation unit 305, (12) as in equation by multiplying the directional gain _G 1 (f) _~G M (f) for each frequency component, by further taking the M th root, the area highlighted The gain H (f) is calculated. Then, the area emphasis gain H (f) obtained by the area emphasis gain calculation unit 305 is given to the target area sound extraction unit 106.

(C-3) Effect of Third Embodiment According to the third embodiment, the following effects can be obtained in addition to the effect of the second embodiment.

In the sound collecting device 300 of the third embodiment, when calculating the area emphasis gain, the root of the number of directional gains to be multiplied is taken, so that the filter that suppresses noise in the signal as in the first embodiment is used. Since it is possible to avoid the process of multiplying multiple sounds, it is possible to emphasize only the target area sound with less distortion.

(D) Fourth Embodiment Hereinafter, the fourth embodiment of the sound collecting device, the program and the method according to the present invention will be described in detail with reference to the drawings.

(D-1) Configuration of Fourth Embodiment The sound collecting device 400 of the fourth embodiment can also be shown with reference to FIG. 1 described above.

In the following, only the difference between the fourth embodiment and the third embodiment will be described.

In the sound collecting device 300 of the third embodiment, when calculating the area emphasis gain, noise is suppressed in the signal as in the first embodiment by taking the root of the number of directional gains to be multiplied. The process of applying multiple filters was avoided. On the other hand, the same effect can be obtained by setting the minimum value of the directivity gain for all the microphone arrays for each frequency component as the area emphasis gain, and further, it can be realized with a smaller amount of calculation than the third embodiment. it can. Therefore, in the sound collecting device 400 of the fourth embodiment, the minimum values of the directivity gains for all the microphone arrays are collected for each frequency component and used as the area emphasis gain.

As shown in FIG. 1, the sound collecting device 400 of the fourth embodiment is different from the sound collecting device 300 of the third embodiment in that the area emphasis gain calculation unit 305 is replaced with the area emphasis gain calculation unit 405. ing.

(D-2) Operation of the Fourth Embodiment Next, the operation of the sound collecting device 400 of the fourth embodiment having the above configuration (sound collecting method of this embodiment) will be described.

Since the operation of the sound collecting device 400 according to the fourth embodiment is the same as the operation of the sound collecting device 300 according to the third embodiment except for the area emphasis gain calculation unit 405, the operation description of other elements will be described. Omit.

Area enhancement gain calculation unit 405 calculates the minimum value of the directional gain _{G 1 (f) ~G M (} f) for all of the microphone array for each frequency component as the area emphasis gain H (f). The area emphasis gain H (f) obtained by the area emphasis gain calculation unit 405 is given to the target area sound extraction unit 106.

As described above, the target area sound and noise do not overlap in the frequency domain based on the sparsity of the voice. Then, as shown in FIG. 2 above, the “directive gain of MA ₁ ” and the “directional gain of MA ₂ ” are set to either 0 or 1 (0 or 1) for the non-purpose area sound component. Any of the approximate values) can be taken, but the frequency components of the target area sound are always 1 (values close to 1). Then, as shown in FIG. 2 (c-2), even if the minimum values of the directivity gains G ₁ (f) and G ₂ (f) are taken for each frequency component, the directivity gain G ₁ for each frequency component is taken. The same or similar values as when the minimum values of (f) and G ₂ (f) are taken can be obtained.

(D-3) Effect of Fourth Embodiment According to the fourth embodiment, the following effects can be obtained in addition to the effect of the third embodiment.

Unlike the third embodiment, the sound collecting device 400 (area emphasis gain calculation unit 405) of the fourth embodiment does not require the calculation of the power root, so that only the target area sound can be emphasized with a smaller amount of calculation. it can.

(E) Other Embodiments The present invention is not limited to each of the above embodiments, and modified embodiments as illustrated below can also be mentioned.

(E-1) in the area enhancement gain calculation unit 105 of the sound pickup apparatus 200 of the second embodiment, when calculating the area emphasis gain, (11), delayed directional gain G _'1 as (f) ~G _{'M (f)} after multiplying, as in the area enhancement gain calculation unit 305 of the third embodiment, by taking the power root of the number of delay directional gain (M), to obtain the area emphasis gain You may do so.

Further, in the area enhancement gain calculation unit 105 of the second embodiment, similarly to the area enhancement gain calculation unit 405 of the fourth embodiment, the delay directional gain G for all microphone arrays MA for each frequency component _'1 ( collect the minimum value of _{f) ~G 'M (f)} , may be obtained as an area emphasis gain.

100 ... Sound collecting device, 102 ... Data input unit, 103 ... Frequency domain conversion unit, 104 ... Directivity gain calculation unit, 105 ... Area emphasis gain calculation unit, 106 ... Target area sound extraction unit.

Claims (7)

A directivity gain calculation means for acquiring the directivity gain when the beam former forms directivity in the target area sound direction for each of the input signals obtained by converting the captured signals output by a plurality of microphone arrays into the frequency domain.
An area enhancement gain calculation means for acquiring an area enhancement gain that emphasizes a target area sound based on the directivity gain of each of the microphone arrays.
It is characterized by having a target area sound acquisition unit that acquires a target area emphasis signal that emphasizes the target area sound based on the input signal of the microphone array and the area emphasis gain acquired by the area emphasis gain calculation unit. Sound collecting device. The sound collecting device according to claim 1, wherein the area-enhanced gain calculating means calculates an area-enhanced gain by multiplying each frequency component by directional gains related to all the microphone arrays. The area enhancement gain calculation means calculates the area enhancement gain by multiplying the directional gains of all the microphone arrays for each frequency component and further taking the root corresponding to the number of the microphone arrays. The sound collecting device according to claim 2, wherein the sound collecting device is characterized. The sound collecting device according to claim 1, wherein the area-enhanced gain calculating means obtains the area-enhanced gain by selecting the minimum value of the directivity gain for all the microphone arrays for each frequency component. Further provided with a correction means for acquiring the directivity gain corrected for the timing deviation of the directivity gains of all the microphone arrays according to the difference in the distance between each microphone array and the target area.
The sound collecting device according to any one of claims 1 to 4, wherein the area enhancement gain calculating means obtains an area enhancement gain using the directivity gain corrected by the correction means. Computer,
A directivity gain calculation means for acquiring the directivity gain when the beam former forms directivity in the target area sound direction for each of the input signals obtained by converting the captured signals output by a plurality of microphone arrays into the frequency domain.
An area enhancement gain calculation means for acquiring an area enhancement gain that emphasizes a target area sound based on the directivity gain of each of the microphone arrays.
Based on the input signal of the microphone array and the area enhancement gain acquired by the area enhancement gain calculation means, it is characterized by functioning as a target area sound acquisition means for acquiring a target area emphasis signal that emphasizes the target area sound. Sound collection program. In the sound collection method
It is equipped with a directivity gain calculation means, an area emphasis gain calculation means, and a target area sound acquisition means.
The directivity gain calculating means acquires the directivity gain when the beam former forms directivity in the target area sound direction for each of the input signals obtained by converting the captured signals output by the plurality of microphone arrays into the frequency domain. And
The area enhancement gain calculating means acquires an area enhancement gain that emphasizes a target area sound based on the directivity gain of each of the microphone arrays.
The target area sound acquisition means acquires a target area emphasis signal that emphasizes the target area sound based on the input signal of the microphone array and the area emphasis gain acquired by the area emphasis gain calculation unit. Sound collection method.

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