JP2018132737A - Sound pick-up device, program and method, and determining apparatus, program and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve determination precision of target area sound in environments with strong background noise.SOLUTION: This invention relates to a sound pick-up device. The sound pick-up device of the present disclosure acquires extracted sound as a result of extracting target area sound using non-target area sound present in a target area direction from output of a beam former, divides each of an input signal and the extracted sound into plural bands, computes a power spectrum ratio between the input signal and the extracted sound for each divided band, determines whether or not target area sound is present in the input signal by employing the power spectrum ratios for each divided band, and outputs the extracted sound as a sound pick-up result when target area sound has been determined to be present.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sound collection device, a program and a method, and a determination device, a program and a method, and can be applied to, for example, a process of emphasizing a sound in a target area and suppressing sounds in other areas.

  There is a beam former (hereinafter referred to as BF) using a microphone array as a technique for separating and collecting only sound in a specific direction in an environment where a plurality of sound sources exist. BF is a technique for forming directivity using the time difference between signals reaching each microphone (see Non-Patent Document 1). BF is roughly divided into two types, an addition type and a subtraction type.

  In particular, the subtraction type BF has an advantage that directivity can be formed with a smaller number of microphones than the addition type BF.

  FIG. 7 is a block diagram showing a configuration related to a conventional subtractive BF.

  In the conventional subtraction type BF shown in FIG. 7, the number of microphones is two.

  The conventional subtractive BF first calculates the time difference between signals arriving at each microphone by sounds that are present in a target direction (hereinafter also referred to as “target sound”) by a delay device, and adds a delay to the target sound. Match the phase. In the conventional subtractor BF delay unit, the time difference is calculated by the following equation (1).

In the following formula (1), d is the distance between the microphones, c is the speed of sound, and τ _i is the delay amount. In the following equation (1), θ _L is an angle from a vertical direction to a target direction with respect to a straight line connecting the microphones.
τ _L = (dsin θ _L ) / c (1)

Here, when the blind spot exists in the direction of the first microphone with respect to the center of the first microphone and the second microphone, the delay unit in the conventional subtractive BF has the input signal x ₁ ( Delay processing is performed for t). Thereafter, the input signal x ₁ (t) subjected to the delay process is subjected to a subtraction process according to the equation (2).
a (t) = x ₂ (t) −x ₁ (t−τ _L ) (2)

The subtraction process in the conventional subtraction type BF can be similarly performed in the frequency domain, and in this case, the expression (2) is changed to the following expression (3).

Here, when θ _L = ± π / 2, the formed directivity is cardioid unidirectional as shown in FIG. 8A, and when θ _L = 0, π, FIG. As shown in (B), the figure is bi-directional. Hereinafter, a filter that forms unidirectionality from an input signal is referred to as a unidirectional filter, and a filter that forms bidirectionality is referred to as a bidirectional filter.

Further, by using a spectral subtraction (hereinafter referred to as “SS”), it is possible to form directivity that is strong against the blind spot of bi-directionality. The formation of directivity by SS follows equation (4). In the equation (4), the input signal X1 of the _first microphone is used, but the same effect can be obtained with the input signal X2 of the _second microphone. Here, β is a coefficient for adjusting the strength of SS. If the value becomes negative during subtraction, flooring processing is performed in which 0 or the original value is replaced with a smaller value. This method uses a bi-directional filter to extract sound that exists outside the target direction (hereinafter also referred to as “non-target sound”), and subtracts the power spectrum of the extracted non-target sound from the power spectrum of the input signal. The target sound can be emphasized.
| Y (ω) | = | X ₁ (ω) | −β | Α (ω) | (4)

  When it is desired to pick up only sound existing in a certain area (hereinafter referred to as “target area sound”), the sound source (hereinafter referred to as “non-target area”) around that area is simply obtained by using the subtractive BF. May also be picked up. Thus, Patent Document 1 proposes a method of collecting a target area sound by using a plurality of microphone arrays, directing directivity from different directions to the target area, and crossing the directivities in the target area.

  Next, an example of the sound collection process of the target area sound described in Patent Document 1 will be described.

  FIG. 9 is an explanatory diagram showing a configuration example of each microphone array in the case of collecting the target area sound from the sound source in the target area using the two microphone arrays MA1 and MA2.

  FIG. 10 is an explanatory diagram (graph) showing the respective BF outputs of the microphone arrays MA1 and MA2 shown in FIG. 9 in the frequency domain. FIGS. 10A and 10B are graphs (image diagrams) showing the BF outputs of the microphone arrays MA1 and MA2 in the frequency domain, respectively.

In the method described in Patent Document 1, first, the ratio of the power of the target area sound included in the BF outputs of the microphone arrays MA1 and MA2 is estimated and used as a correction coefficient. Specifically, when two microphone arrays MA1 and MA2 are used, the correction coefficient for the target area sound power can be calculated by, for example, the equations (5), (6) or (7), (8). it can.

Here, Y _1k (n) and Y _2k (n) are power spectra of the BF outputs of the microphone arrays MA1 and MA2, N is the total number of frequency bins, k is the frequency, and α (n) is a power correction coefficient for the BF output. is there. Further, mode represents the mode value and median represents the median value. Thereafter, each BF output is corrected by the correction coefficient, and SS is performed to extract the non-target area sound existing in the target area direction. Furthermore, the target area sound can be extracted by SS extracting the extracted non-target area sound from the output of each BF.

  FIG. 11 is an explanatory diagram (image is a diagram) showing changes in the power spectrum of each component when the area sound collection process is performed based on the BF output acquired using the microphone arrays MA1 and MA2 shown in FIG.

First, the input signal _{X 1} of the microphone array MA1, obtain BF output _{Y 1} that suppresses the non-target area sound _{N 2} (see FIG. 11 (a)).

In order to extract the non-target area sound N ₁ (n) existing in the direction of the target area viewed from the microphone array MA1, the microphone array MA2 is extracted from the BF output Y ₂ (n) of the microphone array MA1 as shown in the equation (7). SS is obtained by multiplying the BF output Y ₂ (n) by the power correction coefficient α (see FIG. 11B). After that, according to the equation (8), the non-target area sound is SS from each BF output and the target area sound is extracted (see FIG. 11C). γ (n) is a coefficient for changing the strength at the time of SS.
N ₁ (n) = Y ₁ (n) −α (n) Y ₂ (n) (7)
Z ₁ (n) = Y ₁ (n) −γ (n) N ₁ (n) (8)

  In order to extract the target area sound, SS, which is a nonlinear process, is performed using Equations (4) and (8). Therefore, an unpleasant noise called musical noise may occur in a high noise environment.

Therefore, in Patent Document 2, the section where the target area sound exists and the section where the target area sound does not exist are determined. In the section where the target area sound does not exist, the sound that has been subjected to the area sound collection processing is not output. It is suppressed. In order to determine whether the target area sound exists, first, the power spectrum ratio (area sound) between the input signal and the output obtained by extracting the target area sound (hereinafter referred to as “area sound output”) according to the equation (9). Output / input signal). If there is a sound source in the destination area, since the destination area sound to the input signal X ₁ and Area sound output Z ₁ is included in the common power spectral ratios object area sound component is a value close to 1. On the other hand, since the non-target area sound component is suppressed in the area sound output, the power spectrum ratio becomes a small value. In addition, other background noise components are also subjected to SS multiple times in the area sound collection process, so that they are suppressed to some extent without performing dedicated noise suppression processing in advance, and the power spectrum ratio becomes a small value. On the contrary, when the target area sound does not exist, the area sound output includes only weak noise that is not erased as compared with the input signal, so that the power spectrum ratio becomes a small value in the entire area. Due to this feature, if the average of the power spectrum ratio obtained at each frequency according to the equation (10) (hereinafter also referred to as “average power spectrum ratio”) is taken, there is a large difference between when the target area sound is present and when it is not present. Will be born. Here, m and n are the upper limit and the lower limit of the processing band, respectively, and may be set to, for example, 100 Hz to 6 kHz that sufficiently include audio information. In the apparatus described in Patent Document 2, the average power spectrum ratio is determined by a preset threshold value. When it is determined that the target area sound does not exist, no sound is input without outputting the area sound output data or input. Outputs sound with reduced sound gain.

JP 2014-072708 A JP, 2006-127457, A

Asano Tadashi, "Acoustic Technology Series 16 Sound Array Signal Processing-Sound Source Localization / Tracking and Separation-", Acoustical Society of Japan, Corona, February 25, 2011

  If the method described in Patent Document 1 is used, even if a non-target area sound exists around the target area, the target area sound can be collected. Moreover, if the method described in Patent Document 2 is used, it is possible to suppress the influence of musical noise generated in the area sound collection processing. However, in a high noise environment such as a place where there are many people such as an event venue or a place where music is flowing in the surroundings, there is a possibility that the SN ratio deteriorates and the power spectrum of the sound output by the area sound collection becomes small. is there. In such a situation, the average power spectrum ratio between the area sound collection output and the input signal also becomes small. Especially for components with a small power spectrum, such as unvoiced consonants, the difference from the average power spectrum ratio of the non-target area sound section is small, so the target area sound judgment accuracy is poor and part of the target area sound is missing. There is a risk of doing.

  In view of the above problems, a sound collection device, a program, and a method, and a determination device, a program, and a method that can improve the determination accuracy of a target area sound in an environment with strong background noise are desired. .

  The sound collecting device according to the first aspect of the present invention includes (1) directivity forming means for forming directivity in the direction of a target area from an input signal by a beam former, and (2) directivity formed by the directivity forming means. Non-target area sound extracting means for extracting non-target area sound existing in the target area direction; and (3) a non-target area existing in the target area direction extracted by the non-target area sound extracting means from the output of the beam former. A target area sound extracting means for outputting an extracted sound obtained as a result of extracting the target area sound using the sound; (4) a band dividing means for dividing the input signal and the extracted sound into a plurality of bands; ) Power spectrum ratio calculating means for calculating a power spectrum ratio between the input signal and the extracted sound for each divided band divided by the band dividing means; and (6) calculating the power spectrum ratio. Determining means for determining whether a target area sound exists in the input signal using the power spectrum ratio for each divided band calculated in the stage; and (7) determining that the target area sound exists by the determining means. And output means for outputting the extracted sound as a sound collection result.

  The sound collecting program of the second aspect of the present invention is formed by (1) directivity forming means for forming directivity in the direction of a target area by a beam former from an input signal, and (2) the directivity forming means. Non-target area sound extracting means for extracting non-target area sound existing in the target area direction due to directivity; and (3) existing in the target area direction extracted by the non-target area sound extracting means from the output of the beamformer. A target area sound extraction means for outputting an extraction sound obtained by extracting a target area sound using a non-target area sound; and (4) a band division means for dividing the input signal and the extracted sound into a plurality of bands, respectively. (5) power spectrum ratio calculating means for calculating a power spectrum ratio of the input signal and the extracted sound for each of the divided bands divided by the band dividing means; Determining means for determining whether or not a target area sound exists in the input signal using the power spectrum ratio for each divided band calculated by the word spectrum ratio calculating means; and (7) the target area sound by the determining means. When it is determined that the sound is present, it functions as an output means for outputting the extracted sound as a sound collection result.

  The sound collection method of the third aspect of the present invention includes (1) directivity formation means, non-target area sound extraction means, target area sound extraction means, band division means, power spectrum ratio calculation means, determination means, and output means. (2) The directivity forming means forms directivity in the direction of the target area from the input signal by a beamformer. (3) The non-target area sound extraction means is a directivity formed by the directivity forming means. (4) The target area sound extraction means exists in the target area direction extracted by the non-target area sound extraction means from the output of the beamformer. (5) The extracted sound obtained by extracting the target area sound using the non-target area sound is output. (5) The band dividing unit divides the input signal and the extracted sound into a plurality of bands. Above The power spectrum ratio calculating means calculates a power spectrum ratio between the input signal and the extracted sound for each divided band divided by the band dividing means. (7) The determining means is the power spectrum ratio calculating means. Using the calculated power spectrum ratio for each divided band, it is determined whether or not a target area sound exists in the input signal. (8) The output means determines that the target area sound exists in the determining means. The extracted sound is output as a sound collection result when the sound is collected.

  The determination apparatus of the fourth aspect of the present invention includes (1) directivity forming means for forming directivity in the direction of a target area from an input signal by a beamformer, and (2) an object based on directivity formed by the directivity forming means. Non-target area sound extracting means for extracting non-target area sound existing in the area direction; and (3) non-target area sound existing in the target area direction extracted by the non-target area sound extracting means from the output of the beamformer. A target area sound extracting means for outputting an extracted sound obtained as a result of extracting the target area sound by using (4), a band dividing means for dividing the input signal and the extracted sound into a plurality of bands, and (5) Power spectrum ratio calculating means for calculating a power spectrum ratio between the input signal and the extracted sound for each divided band divided by the band dividing means; and (6) calculating the power spectrum ratio. Using power spectral ratios for each divided band calculated in stage, and having a determining means for determining whether or not sound object area is present in the input signal.

  According to a fifth aspect of the present invention, there is provided a determination program, comprising: (1) directivity forming means for forming directivity from an input signal in a target area direction by a beamformer; and (2) directivity formed by the directivity forming means. Non-target area sound extraction means for extracting non-target area sound existing in the direction of the target area due to the nature, and (3) non-target area sound extraction means that is extracted in the target area direction extracted by the non-target area sound extraction means from the output of the beam former. A target area sound extracting means for outputting an extracted sound obtained by extracting the target area sound using the target area sound; and (4) a band dividing means for dividing the input signal and the extracted sound into a plurality of bands, respectively. (5) Power spectrum ratio calculation means for calculating a power spectrum ratio between the input signal and the extracted sound for each divided band divided by the band dividing means; (6) Using word spectrum ratio calculating means power spectral ratios for each calculated sub-bands in, characterized in that to function as determination means for determining whether or not sound object area is present in the input signal.

  The determination method of the sixth aspect of the present invention includes (1) directivity formation means, non-target area sound extraction means, target area sound extraction means, band division means, power spectrum ratio calculation means, and determination means. ) The directivity forming means forms directivity in the direction of the target area from the input signal by a beamformer. (3) The non-target area sound extracting means is a target area by directivity formed by the directivity forming means. (4) The target area sound extracting means extracts the non-target area sound existing in the direction of the target area extracted by the non-target area sound extracting means from the output of the beamformer. (5) The band dividing means divides the input signal and the extracted sound into a plurality of bands, respectively, and (6) the power spectrum is output. Toll ratio calculating means calculates a power spectrum ratio of the input signal and the extracted sound for each divided band divided by the band dividing means. (7) The determining means is calculated by the power spectrum ratio calculating means. Using the power spectrum ratio for each divided band, it is determined whether a target area sound exists in the input signal.

  ADVANTAGE OF THE INVENTION According to this invention, the determination precision of the target area sound can be improved in the environment where background noise is strong.

It is the block diagram shown about the functional structure of the sound collection device (determination device) concerning a 1st embodiment. It is the figure (graph) shown about the example which the frequency band division part which concerns on 1st Embodiment divided | segmented the power spectrum of the process target signal for every division | segmentation band. It is the figure (graph) shown about the average power spectrum ratio for every division band which the average power spectrum ratio calculation part classified by zone concerning a 1st embodiment computed. It is the block diagram shown about the functional structure of the sound collection apparatus (determination apparatus) which concerns on 2nd Embodiment. It is the flowchart shown about the operation | movement of the target area sound determination process of the sound collection device (determination apparatus) which concerns on 2nd Embodiment. It is the block diagram shown about the functional structure of the sound collection device (judgment device) which concerns on 3rd Embodiment. It is a block diagram which shows the structure which concerns on the subtraction type BF in case the number of conventional microphones is two. It is a figure which shows the directional characteristic formed by the subtraction type | mold BF using the conventional two microphones. It is explanatory drawing shown about the example of a structure of each microphone array in the case of picking up the target area sound from the sound source of a target area using two conventional microphone arrays. It is explanatory drawing shown in the frequency domain about each BF output of the conventional two microphone array. It is explanatory drawing shown about the change of the power spectrum of each component at the time of area sound collection processing based on BF output acquired using the conventional two microphone arrays.

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

(A-1) Configuration of the First Embodiment FIG. 1 is a block diagram showing the functional configuration of the sound collection device 100 of this embodiment.

  The sound collection device 100 uses two microphone arrays MA (MA1, MA2) to perform target area sound collection processing for collecting a target area sound from a sound source in the target area.

  The microphone arrays MA1 and MA2 are arranged at any place in the air where the target area exists. For example, as shown in FIG. 9, the positions of the microphone arrays MA1 and MA2 with respect to the target area may be anywhere as long as the directivity overlaps only in the target area. Each microphone array MA is composed of two or more microphones M, and an acoustic signal is collected by each microphone M. In this embodiment, description will be made assuming that two microphones M (M1, M2) that collect sound signals are arranged in each microphone array MA. That is, each microphone array MA constitutes a 2ch microphone array. The number of microphone arrays MA is not limited to two. When there are a plurality of target areas, it is necessary to arrange a number of microphone arrays MA that can cover all areas.

  The sound collection device 100 includes a data input unit 1, a directivity forming unit 2, a delay correction unit 3, spatial coordinate data 4, a target area sound power correction coefficient calculation unit 5, a target area sound extraction unit 6, a frequency band division unit 7, A band-specific average power spectrum ratio calculation unit 8 and an area sound determination unit 9 are provided. Detailed processing of each functional block constituting the sound collection device 100 will be described later.

  In this embodiment, the sound collection device 100 that outputs the sound collection result of the target area sound based on the determination processing result of whether or not the target area sound exists in the input signal will be described. As a determination device (determination program, determination method) for outputting the determination process result of the target area sound by omitting the output means for outputting the sound collection result of the target area sound (part of the processing of the area sound determination unit 9) You may make it comprise.

  The sound collection device 100 may be configured entirely by hardware (for example, a dedicated chip or the like), or may be partially or entirely configured as software (program). For example, the sound collection device 100 may be configured by installing a program (including the determination program and the sound collection program of the embodiment) in a computer having a processor and a memory.

(A-2) Operation of First Embodiment Next, the operation (determination method and sound collection method according to the embodiment) of the sound collection device 100 of the first embodiment having the above-described configuration will be described. .

  The data input unit 1 converts the acoustic signals collected by the microphone arrays MA1 and MA2 from analog signals to digital signals. And the data input part 1 performs the conversion process (For example, the process converted from a time domain to a frequency domain using a fast Fourier transform etc.) about the said digital signal.

  The directivity forming unit 2 extracts, for each microphone array MA, a non-target area sound that exists in a direction other than the target direction (for example, by a bi-directional filter), and extracts the amplitude spectrum of the extracted non-target area sound of the input signal. By subtracting from the amplitude spectrum, a sound having a directivity in the direction of the target area (BF output) is acquired. Specifically, the directivity forming unit 2 acquires, as a BF output, a sound in which directivity is formed in the direction of the target area by BF according to the equation (4) for each microphone array MA. When the input signal is not a microphone array MA but a signal input from a directional microphone, the processing of the directivity forming unit 2 is omitted and the input signal is supplied as it is to the subsequent stage side. Also good.

  The delay correction unit 3 calculates and corrects a delay caused by a difference in distance between the target area and each microphone array MA (MA1, MA2). The delay correction unit 3 obtains the position of the target area and the position of the microphone array from the spatial coordinate data 4, and calculates the difference in arrival time of the target area sound to each microphone array MA (MA1, MA2). Next, the delay correcting unit 3 uses the microphone array MA (MA1, MA2) arranged farthest from the target area as a reference so that the target area sound reaches all the microphone arrays MA (MA1, MA2) simultaneously. Add a delay to

  The spatial coordinate data 4 holds position information of all target areas, microphone arrays MA (MA1, MA2), and microphones M (M1, M2) constituting each microphone array MA (MA1, MA2).

  The target area sound power correction coefficient calculation unit 5 calculates a correction coefficient for making the power of the target area sound component included in each BF output the same according to the equation (5) or (6).

  The target area sound extraction unit 6 performs SS on each BF output data corrected by the correction coefficient calculated by the target area sound power correction coefficient calculation unit 5 according to the equation (7), and extracts noise existing in the target area direction. Further, the target area sound extraction unit 6 extracts the target area sound by performing SS on the extracted noise from the output of each BF according to the equation (8).

Frequency band division unit 7 obtains an input signal from the data input unit 1, and the area sound output Z ₁ from the target area sound extraction unit 6 divides each of a plurality of bands. Here, it is assumed that the bandwidth of the input signal and the area sound output is the same.

In the following, as an input signal to be processed in the frequency band division unit 7 and the band-by-band average power spectrum ratio calculating unit 8, it is assumed to be used on behalf of the input signal X ₁ of the microphone array MA1, other microphone (other It may be replaced with the input signal of the microphone array MA).

For example, the frequency band dividing unit 7 divides a signal to be processed (input signal X ₁ and area sound output Z ₁ ) by a predetermined frequency bandwidth (constant interval or indefinite interval). Hereinafter, the frequency band division unit 7 divides a frequency to be processed into a plurality of frequency bands, which are referred to as “divided bands”, and signals in each divided band (signals divided from the signals to be divided) are “divided band signals”. ".

  The frequency band dividing unit 7 may set the bandwidths of the respective divided bands to be equal (equal intervals), or may be set with a bias depending on the frequency band. For example, the frequency band dividing unit 7 may set a wider divided band as the frequency is higher (set a smaller divided band as the frequency is lower). For example, the frequency band dividing unit 7 sets divided bands at 100 Hz intervals for low frequency bands (for example, less than 1 kHz), and sets divided bands at 1 kHz intervals for non-low frequency bands (for example, 1 kHz or more). You may do it.

  In addition, the frequency band dividing unit 7 sets a divided band within a predetermined band (for example, a range of 100 hz to 6 kHz) in which audio information (sound component) is sufficiently included, and signals in other frequency bands You may make it discard (it cuts off as the object of a division | segmentation band).

  In the example of this embodiment, in order to simplify the description, the frequency band dividing unit 7 will be described below assuming that the signal to be processed is divided into divided bands of 1 kHz intervals.

  FIG. 2 is a diagram (a graph showing a power spectrum for each band) illustrating an example of a processing target signal processed by the frequency band dividing unit 7.

FIG. 2 shows an example in which the frequency band dividing unit 7 divides a processing target signal in a band from 100 Hz to 6 kHz into six divided bands B _{1 to} B ₆ at approximately 1 kHz intervals.

The band-specific average power spectrum ratio calculation unit 8 calculates the power spectrum for each divided band (divided band signal) divided by the frequency band dividing unit 7 for each processing target signal (input signal X ₁ and area sound output Z ₁ ). Extract (acquire). Then, the band-specific average power spectrum ratio calculation unit 8 calculates the average power spectrum ratio (the average of the power spectrum ratios in each divided band) based on the equation (11) for each divided band.

In Expression (11), “R _j ” is an average power spectrum ratio in the j-th divided band (j is an integer from 1 to M; M is the total number of divided bands (number of divided bands)). . In Expression (11), “X _1j ” is an average power spectrum (average value of power spectrum) in the j-th divided band in the input signal X ₁ of the microphone array MA1, and “Z _1j ” is an area sound. is the average power spectrum of the j-th divided band in the output Z ₁ (average value of the power spectrum).

For example, it is assumed that the frequency band dividing unit 7 divides each signal to be processed (input signal X ₁ and area sound output Z ₁ ) into six divided bands B _{1 to} B _{6 as shown} in FIG. . In this case, the band-specific average power spectrum ratio calculation unit 8 and the band-specific average power spectrum ratio calculation unit 8 respectively calculate the average power spectrum X _{11 to} X _{16 of the} input signal from the divided bands B _{1 to} B ₆ of the input signal X _1. To get. Furthermore, per-band average power spectrum ratio calculating unit 8 obtains an average power spectrum _Z 11 _{to Z 16} each area sound output from the sub-bands _B 1 .about.B ₆ area sound output _{Z 1.}

Then, the band-by-band average power spectrum ratio calculating unit _8, X 11 _{to X 16,} and _Z 11 _{to Z 16} calculates the average power spectrum ratio _R 1 to R ₆ of each divided band is applied to equation (11) .

FIG. 3 is a diagram (graph) showing the average power spectrum ratios R _{1 to} R ₆ for each divided band calculated by the band-specific average power spectrum ratio calculation unit 8.

FIG. 3 shows the average power spectrum ratios R _{1 to} R ₆ for each divided band and the average power spectrum (rightmost value) in all bands.

Then, the band-specific average power spectrum ratio calculation unit 8 calculates the maximum value (average power spectrum ratio) from the average power spectrum ratios R _{1 to} R ₆ for each divided band according to the equation (12), and the maximum average power spectrum ratio U. Get as _max .

For example, when the values of the average power spectrum ratios R _{1 to} R ₆ for each divided band are as shown in FIG. 3, the maximum average power spectrum ratio U _max is the value of the divided band B ₆ , and It can be seen that the value is larger than the average power spectrum.

The area sound determination unit 9 compares the maximum average power spectrum ratio U _max calculated by the band-specific average power spectrum ratio calculation unit 8 with a preset threshold value T1, and determines whether or not the target area sound exists (the input signal has a target Whether or not an area sound is included). For example, the area sound determination unit 9 determines that the target area sound is present when the maximum average power spectrum ratio U _max exceeds the threshold value T1, and the target area sound is determined when the maximum average power spectrum ratio U _max is equal to or less than the threshold value T1. You may make it determine with not existing.

If the area sound determination unit 9 determines that the target area sound exists, the area sound determination processing data (area sound output Z ₁ (extracted sound)) may be output as it is. On the other hand, when it is determined that the target area sound does not exist, the area sound determination unit 9 outputs silent sound data without outputting the area sound collection processing data (area sound output Z ₁ (extracted sound)). You may do it. The area sound determination unit 9 may output the input signal (for example, the input signal X ₁ of the microphone array MA1) with a weakened gain instead of the silent sound data.

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

In the sound collection device 100 of the first embodiment, the input signal (X _{1 in the} above example) and the area sound output Z ₁ are divided into a plurality of divided bands, an average power spectrum ratio for each divided band is obtained, and the maximum Based on the maximum average power spectrum ratio U _max that is a value, it is determined whether or not the target area sound exists.

In other words, in the sound collecting device 100 of the first embodiment, if there is even one divided band whose average power spectrum ratio exceeds the threshold (T1 in the above example), it is determined that the target area sound exists. When human voice is used as the target area sound, the power of the unvoiced consonant is small, but the power spectrum has a peak. Therefore, if the band is divided, the power of the band including the peak is increased. Since the characteristics as described above exist, the maximum value (maximum average power spectrum ratio U _max ) of the average power spectrum ratio for each divided band is different from the average power spectrum ratio of the entire band (for example, musical noise or the like). The difference between the non-target area sound section where the noise is generated and the target area sound section becomes clear. Therefore, in the sound collection device 100 of the first embodiment, the determination accuracy of the target area sound is improved in an environment where the background noise is strong compared to the conventional target area sound determination using the average power spectrum ratio of the entire band. Can be improved.

Furthermore, in the first embodiment, since the target area sound is determined using the maximum value of the average power spectrum ratio for each divided band (maximum average power spectrum ratio U _max ), the band used for the target area sound determination is peaked. Although the determination is not performed using only one sample while being localized in the periphery, it is possible to perform a stable determination process that is not easily influenced by noise generated in a burst manner.

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

(B-1) Configuration of Second Embodiment FIG. 4 is a block diagram showing a functional configuration of the sound collection device 100A of this embodiment. In FIG. 4, the same or corresponding parts as those in FIG.

  Hereinafter, the difference from the first embodiment will be described for the sound collection device 100A of the second embodiment.

  The sound collection device 100A is different from the first embodiment in that the area sound determination unit 9 is replaced with an area sound determination unit 9A, and an all-band average power spectrum ratio calculation unit 10 is added.

  The all-band average power spectrum ratio calculation unit 10 calculates an average power spectrum ratio in all bands.

  The area sound determination unit 9A controls the frequency band division unit 7, the band-specific average power spectrum ratio calculation unit 8, and the all-band average power spectrum ratio calculation unit 10 to determine the presence or absence of the target area sound.

(B-2) Operation of the Second Embodiment Next, the operation (the determination method and the sound collection method according to the embodiment) of the sound collection device 100A of the second embodiment having the above configuration is described first. Differences from the embodiment will be described.

  The sound collection device 100A is different from the first embodiment in that the target area sound determination processing by the area sound determination unit 9A is different. Below, the determination process of the target area sound centering on the area sound determination part 9A is demonstrated.

  FIG. 5 is a flowchart showing the determination process of the target area sound by the sound collection device 100A (area sound determination unit 9A).

  In the flowchart of FIG. 5, T1, T2, and T3 used for the area sound determination process are threshold values. The threshold T1 can be the same as that in the first embodiment. The threshold value T2 is assumed to be a value larger than the threshold value T3 (T2> T3). The magnitude relationship between “T1” and “T2, T3” is not limited, and a suitable value confirmed by an experiment or the like can be applied.

  First, the area sound determination unit 9A controls the all-band average power spectrum ratio calculation unit 10 to calculate the all-band average power spectrum ratio (S101).

  The all-band average power spectrum ratio calculation unit 10 calculates the all-band average power spectrum ratio according to the equations (9) and (10).

  Next, the area sound determination unit 9A determines whether or not the all-band average power spectrum ratio calculated by the all-band average power spectrum ratio calculation unit 10 exceeds the threshold T2 (whether U> T2 or not). S102). The area sound determination unit 9A operates from step S104 to be described later when the all-band average power spectrum ratio exceeds the threshold value T2, and operates from step S103 to be described otherwise.

  When the all-band average power spectrum ratio exceeds the threshold value T2 (when U> T2), the area sound determination unit 9A determines that the target area sound exists (S104), and ends the target area sound determination process. .

  On the other hand, when the all-band average power spectrum ratio is equal to or less than the threshold T2 (when U ≦ T2), the area sound determination unit 9A determines whether the all-band average power spectrum ratio exceeds the threshold T3 (U> T3). (S103). The area sound determination unit 9A operates from step S105 described later when the all-band average power spectrum ratio exceeds the threshold T3, and operates from step S108 described later otherwise.

  When the all-band average power spectrum ratio exceeds the threshold T3 (when U> T3), the area sound determination unit 9A controls the frequency band division unit 7 and the band-specific average power spectrum ratio calculation unit 8 to The average power spectrum ratio is calculated for each divided band by the same processing as in the first embodiment (S105).

Next, similarly to the first embodiment, the area sound determination unit 9A controls the band-specific average power spectrum ratio calculation unit 8 to obtain the maximum average power spectrum ratio U _max from the average power spectrum ratio for each divided band. It is calculated, and it is determined whether or not the maximum average power spectrum ratio U _max exceeds the threshold T1 (S106). In other words, the area sound determination unit 9A and the band-specific average power spectrum ratio calculation unit 8 perform a process of determining whether or not there is an average power spectrum ratio for each divided band that exceeds the threshold T1.

When the maximum average power spectrum ratio U _max exceeds the threshold value T1 (when there is an average power spectrum ratio for each divided band that exceeds the threshold value T1), the area sound determination unit 9A operates from step S107 described later, and is not so. In this case, the operation starts from step S108 described later.

When the maximum average power spectrum ratio U _max exceeds the threshold T1 (when U _max > T1), the area sound determination unit 9A determines that the target area sound exists (S107), and ends the determination process of the target area sound. .

On the other hand, when the all-band average power spectrum ratio is equal to or less than the threshold T3 in the above-described step S103 (when U ≦ T3), or when the maximum average power spectrum ratio U _max is equal to or less than the threshold T1 in the above-described step S106 (U _max ≦ In the case of T1), the area sound determination unit 9A determines that there is no target area sound (S108), and ends the determination process of the target area sound.

  The area sound determination unit 9A first causes the all-band average power spectrum ratio calculation unit 10 to calculate the all-band average power spectrum ratio, and determines the target area sound based on the all-band average power spectrum ratio (hereinafter referred to as “No. 1 determination process). Specifically, the area sound determination unit 9A determines that the target area sound exists when the all-band average power spectrum ratio is larger than the threshold T2 as described above, and when the all-band average power spectrum ratio is equal to or less than the threshold T3. It is determined that there is no destination area sound.

Then, the area sound determination unit 9A determines that the target area sound cannot be determined by the first determination process when the all-band average power spectrum ratio is equal to or less than the threshold T2 and exceeds the threshold T3 (T2 ≦ U> T3). The frequency band dividing unit 7 and the band-specific average power spectrum ratio calculating unit 8 are controlled to calculate the maximum average power spectrum ratio U _max by the same processing as in the first embodiment, and the maximum average power spectrum ratio A process of determining the presence or absence of a target area sound based on U _max (hereinafter referred to as “second determination process”) is performed.

(B-3) Effects of Second Embodiment According to the second embodiment, the following effects can be achieved.

The sound collection device 100A (area sound determination unit 9A) of the second embodiment first performs a target area sound determination process (first determination process) based on the entire band average power spectrum ratio, and the entire band average power spectrum. When the ratio is equal to or smaller than the threshold T2 and exceeds the threshold T3 (T2 ≦ U> T3), the target area sound determination process (second determination process) is performed based on the maximum average power spectrum ratio U _max .

Thereby, the sound collection device 100A (area sound determination unit 9A) can perform the determination process of the target area sound with sufficient accuracy only by the first determination process (determination process based on the entire band average power spectrum ratio). For example (when the all-band average power spectrum ratio is sufficiently large), the second determination process (band division process or the like) is not performed. On the other hand, the sound collection device 100A (area sound determination unit 9A) cannot perform the target area sound determination process with sufficient accuracy in the first determination process (determination process based on the entire band average power spectrum ratio) (for example, Only when the average power spectrum ratio U is small as in the case of an unvoiced consonant, the second determination process (a process of determining the target area sound by calculating the maximum average power spectrum ratio U _max by band division) is performed.

  That is, the sound collection device 100A (area sound determination unit 9A) performs the second band division with a larger processing amount only when the target area sound can be determined with sufficient accuracy in the first determination process. Since the determination process is performed, an efficient target area sound determination process can be performed.

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

(C-1) Configuration of Third Embodiment FIG. 6 is a block diagram showing a functional configuration of the sound collection device 100B of this embodiment. In FIG. 6, the same or corresponding parts as those in FIG.

  Below, the difference with 1st Embodiment is demonstrated about the sound collection apparatus 100B of 3rd Embodiment.

  The sound collection device 100B is different from the first embodiment in that the area sound determination unit 9 is replaced with an area sound determination unit 9B, and an interband power spectrum ratio calculation unit 11 is added.

The inter-band power spectrum ratio calculation unit 11 calculates a minimum value (hereinafter referred to as “minimum average power spectrum ratio U _min ”) from the average power spectrum ratio for each divided band obtained by the band-specific average power spectrum ratio calculation unit 8. To do. Then, the inter-band power spectrum ratio calculation unit 11 calculates the maximum average power spectrum ratio U _max (the maximum value of the average power spectrum ratio R for each divided band) obtained by the band-specific average power spectrum ratio calculation unit 8 and the minimum average power. A ratio of spectrum ratio U _min (hereinafter referred to as “interband power spectrum ratio V”) is obtained.

  The area sound determination unit 9B is different from the first embodiment in that the target area sound is determined based on the inter-band power spectrum ratio V.

  In the second embodiment, the second determination process may be replaced with a determination process using the interband power spectrum ratio V.

(C-2) Operation of the Third Embodiment Next, the operation (the determination method and the sound collection method according to the embodiment) of the sound collection device 100B of the third embodiment having the above configuration is described first. Differences from the embodiment will be described.

  The sound collection device 100B is different from the first embodiment in that the determination process of the target area sound by the area sound determination unit 9B is different. Below, the determination process of the target area sound centering on the area sound determination part 9B is demonstrated.

The inter-band power spectrum ratio calculation unit 11 calculates the minimum average power spectrum ratio U _min from the average power spectrum ratio for each divided band determined by the band-based average power spectrum ratio calculation unit 8 according to the equation (13).

Then, the inter-band power spectrum ratio calculation unit 11 calculates the inter-band power spectrum ratio V based on the maximum average power spectrum ratio U _max and the minimum average power spectrum ratio U _min according to the equation (14).

For example, when the value of the average power spectrum ratio (R _{1 to} R ₆ ) for each divided band is as shown in FIG. 3, the maximum average power spectrum ratio U _max is the value of the divided band B ₆ , and the minimum average The value of the power spectrum ratio U _{min is} the value of the divided band B ₃ .

  The area sound determination unit 9B compares the power spectrum ratio V between the bands and the threshold T4, and determines that the target area sound exists when the power spectrum ratio V between the bands is larger than the threshold T4 (when V> T4), When the inter-band power spectrum ratio V is equal to or less than the threshold value T4 (when V ≦ T4), it is determined that there is no target area sound.

(C-3) Effects of the Third Embodiment According to the third embodiment, the following effects can be achieved as compared with the first embodiment.

  In the sound collection device 100B of the third embodiment, since the target area sound is detected based on the interband power spectrum ratio V, a target area sound component having a smaller power spectrum can also be detected.

(D) Other Embodiments The present invention is not limited to the above-described embodiments, and may include modified embodiments as exemplified below.

(D-1) In each of the above-described embodiments, the area sound determination unit 9 (9A, 9B) determines that the maximum average power for a few seconds thereafter when the maximum average power spectrum ratio U _max is greater than a certain value by more than a threshold value T1. You may make it respond | correspond to the function (hangover function) which determines that the target area sound exists irrespective of the spectrum ratio _Umax .

(D-2) In the sound collection device (determination device) of each of the above embodiments, the average power spectrum ratio for each divided band is calculated, and the maximum average power spectrum ratio U _max that is the maximum value is used for target area sound determination. Although it is used, one representative value of the power spectrum ratio in each divided band is obtained instead of the average value (average power spectrum ratio) of the power spectrum ratio in each divided band, and the representative value (hereinafter referred to as “representative power”). The maximum value (hereinafter referred to as “maximum representative power spectrum ratio”) of the “spectrum ratio” may be used by replacing it with the maximum average power spectrum ratio U _max .

That is, in each of the embodiments described above, the band-specific average power spectrum ratio calculation unit 8 acquires the representative power spectrum ratio from each divided band, and sets the maximum value of the representative power spectrum ratio of each divided band as the maximum representative power spectrum ratio. It may be acquired and replaced with the maximum average power spectrum ratio U _max for use in target area sound determination. In each of the above embodiments, the position for obtaining the representative power spectrum ratio (representative value) from each divided band is not limited, but for example, the median value or the like may be obtained.

As described above, in each of the above embodiments, in the target area sound determination, the maximum value (for example, the maximum average power spectrum ratio U) of the power spectrum ratio (for example, the average power spectrum ratio or the representative power spectrum ratio) for each divided band. _max , maximum representative power spectrum ratio, etc.).

  DESCRIPTION OF SYMBOLS 100 ... Sound collecting device (determination device), 1 ... Signal input part, 2 ... Directionality formation part, 3 ... Delay correction part, 4 ... Spatial coordinate data, 5 ... Target area sound power correction coefficient calculation part, 6 ... Target area Sound extraction unit, 7... Frequency band division unit, 8... Average power spectrum ratio calculation unit by band, 9... Area sound determination unit, MA, MA1, MA2 .. microphone array, M, M1, M2.

Claims (11)

Directivity forming means for forming directivity in the direction of the target area by a beamformer from an input signal;
Non-target area sound extracting means for extracting non-target area sound existing in the target area direction due to directivity formed by the directivity forming means;
A target area sound extraction means for outputting a sound extracted as a result of extracting a target area sound using a non-target area sound existing in a target area direction extracted by the non-target area sound extraction means from the output of the beam former; ,
Band dividing means for dividing the input signal and the extracted sound into a plurality of bands, respectively.
Power spectrum ratio calculating means for calculating a power spectrum ratio of the input signal and the extracted sound for each divided band divided by the band dividing means;
Determining means for determining whether or not a target area sound exists in the input signal, using the power spectrum ratio for each divided band calculated by the power spectrum ratio calculating means;
And an output means for outputting the extracted sound as a sound collection result when it is determined by the determination means that a target area sound exists.   The determination means determines whether a target area sound exists in the input signal according to a comparison result between the maximum value of the power spectrum ratio for each divided band calculated by the power spectrum ratio calculation means and the first threshold value. The sound collecting device according to claim 1, wherein the sound collecting device is determined. A total band average power spectrum ratio calculating means for calculating an average power spectrum ratio of the entire band of the input signal and the extracted sound;
The determination means first determines whether or not a target area sound exists in the input signal based on the average power spectrum ratio of the all bands calculated by the all band average power spectrum ratio calculation means. Process
The band dividing unit divides the input signal and the extracted sound into a plurality of bands, respectively, when it is not possible to determine whether a target area sound exists in the input signal in the first determination process,
The power spectrum ratio calculation means, for each band that is divided by the band dividing means, when the first determination process cannot determine whether a target area sound exists in the input signal. Calculate the power spectrum ratio of the signal and the extracted sound,
The determination means determines the input signal from the power spectrum ratio calculated by the power spectrum ratio calculation means when the first determination processing cannot determine whether or not a target area sound exists in the input signal. The sound collection device according to claim 1, wherein a second determination process is performed to determine whether or not there is a target area sound.   In the first determination process, when the average power spectrum ratio of all the bands calculated by the all-band average power spectrum ratio calculating unit is a value exceeding a second threshold value in the first determination process, When it is determined that sound is present, and the average power spectrum ratio of the entire band calculated by the all-band average power spectrum ratio calculating unit is a value equal to or smaller than a third threshold smaller than the second threshold, the input signal When it is determined that the target area sound does not exist and the average power spectrum ratio of the entire band calculated by the all-band average power spectrum ratio calculating unit exceeds the third threshold and is equal to or less than the second threshold. 4. The sound collecting device according to claim 3, wherein a result that it cannot be determined whether or not a target area sound exists in the input signal is obtained.   In the second determination process, the determination unit includes a target area in the input signal according to a comparison result between the maximum value of the power spectrum ratio for each divided band calculated by the power spectrum ratio calculation unit and the first threshold value. The sound collecting device according to claim 3, wherein it is determined whether or not sound exists.   The determination means is responsive to a comparison result between the fourth threshold and the inter-band power spectrum ratio represented by the ratio between the maximum value and the minimum value of the power spectrum ratio for each divided band calculated by the power spectrum ratio calculation means. The sound collection device according to claim 1, wherein it is determined whether or not a target area sound exists in the input signal. Computer
Directivity forming means for forming directivity in the direction of the target area by a beamformer from an input signal;
Non-target area sound extracting means for extracting non-target area sound existing in the target area direction due to directivity formed by the directivity forming means;
A target area sound extraction means for outputting a sound extracted as a result of extracting a target area sound using a non-target area sound existing in a target area direction extracted by the non-target area sound extraction means from the output of the beam former; ,
Band dividing means for dividing the input signal and the extracted sound into a plurality of bands, respectively.
Power spectrum ratio calculating means for calculating a power spectrum ratio of the input signal and the extracted sound for each divided band divided by the band dividing means;
Determining means for determining whether or not a target area sound exists in the input signal, using the power spectrum ratio for each divided band calculated by the power spectrum ratio calculating means;
A sound collection program which functions as an output means for outputting the extracted sound as a sound collection result when it is determined by the determination means that a target area sound exists. Directivity forming means, non-target area sound extraction means, target area sound extraction means, band division means, power spectrum ratio calculation means, determination means, and output means,
The directivity forming means forms directivity in the direction of the target area by a beamformer from an input signal,
The non-target area sound extracting means extracts non-target area sound existing in the target area direction due to the directivity formed by the directivity forming means,
The target area sound extraction means extracts the extracted sound as a result of extracting the target area sound from the output of the beamformer using the non-target area sound existing in the target area direction extracted by the non-target area sound extraction means. Output,
The band dividing unit divides the input signal and the extracted sound into a plurality of bands,
The power spectrum ratio calculating means calculates a power spectrum ratio of the input signal and the extracted sound for each divided band divided by the band dividing means,
The determination means determines whether or not there is a target area sound in the input signal using the power spectrum ratio for each divided band calculated by the power spectrum ratio calculation means,
The output means outputs the extracted sound as a sound collection result when the determination means determines that a target area sound is present. Directivity forming means for forming directivity in the direction of the target area by a beamformer from an input signal;
Non-target area sound extracting means for extracting non-target area sound existing in the target area direction due to directivity formed by the directivity forming means;
A target area sound extraction means for outputting a sound extracted as a result of extracting a target area sound using a non-target area sound existing in a target area direction extracted by the non-target area sound extraction means from the output of the beam former; ,
Band dividing means for dividing the input signal and the extracted sound into a plurality of bands, respectively.
Power spectrum ratio calculating means for calculating a power spectrum ratio of the input signal and the extracted sound for each divided band divided by the band dividing means;
And a determination unit that determines whether or not a target area sound exists in the input signal using the power spectrum ratio for each divided band calculated by the power spectrum ratio calculation unit. Computer
Directivity forming means for forming directivity in the direction of the target area by a beamformer from an input signal;
Non-target area sound extracting means for extracting non-target area sound existing in the target area direction due to directivity formed by the directivity forming means;
A target area sound extraction means for outputting a sound extracted as a result of extracting a target area sound using a non-target area sound existing in a target area direction extracted by the non-target area sound extraction means from the output of the beam former; ,
Band dividing means for dividing the input signal and the extracted sound into a plurality of bands, respectively.
Power spectrum ratio calculating means for calculating a power spectrum ratio of the input signal and the extracted sound for each divided band divided by the band dividing means;
The determination functioning as a determination unit that determines whether or not a target area sound exists in the input signal, using the power spectrum ratio for each divided band calculated by the power spectrum ratio calculation unit. program. Directivity forming means, non-target area sound extraction means, target area sound extraction means, band division means, power spectrum ratio calculation means, and determination means,
The directivity forming means forms directivity in the direction of the target area by a beamformer from an input signal,
The non-target area sound extracting means extracts non-target area sound existing in the target area direction due to the directivity formed by the directivity forming means,
The target area sound extraction means extracts the extracted sound as a result of extracting the target area sound from the output of the beamformer using the non-target area sound existing in the target area direction extracted by the non-target area sound extraction means. Output,
The band dividing unit divides the input signal and the extracted sound into a plurality of bands,
The power spectrum ratio calculating means calculates a power spectrum ratio of the input signal and the extracted sound for each divided band divided by the band dividing means,
The determination means determines whether or not a target area sound exists in the input signal, using the power spectrum ratio for each divided band calculated by the power spectrum ratio calculation means.

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