JP2013179388A - Acoustic signal enhancement device, perspective determination device, method and program therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acoustic signal enhancement device which reproduces the acoustic signal of a sound source, by determining the reverberant ratio estimate of the acoustic signal precisely.SOLUTION: A direct sound direction power estimation unit obtains the power estimate of a direct sound direction signal obtained by performing a process for passing only the signal component arriving from the direct sound source direction, by means of a predetermined beam former achieved by a microphone array. A reverberant sound direction power estimation unit obtains the power estimate of a reverberant sound direction signal subjected to processing for passing the signal component arriving from other than the direct sound source direction, by means of a beam former set so that the signal component arriving from other than the direct sound source direction has the same directivity shape as that of the beam former, and the direction of main beam avoiding the direct sound source direction. A reverberant ratio estimation unit obtains a reverberant ratio estimate DRR indicating the ratio of power estimate of direct sound to power estimate of a reverberant sound direction signal, by using the power estimate of a frequency region signal and the power estimate of a reverberant sound direction signal.

Description

  The present invention relates to a technique for estimating a direct ratio of an acoustic signal.

  In the prior art shown in Patent Document 1, the received sound signal of the microphone array is converted to the frequency domain in order to obtain the direct ratio, and the power of each of the direct sound and the indirect sound is calculated using the spatial correlation matrix obtained from the signal. (See, for example, paragraphs [0034] to [0061] of Example 1).

JP 2009-201724 A

  In the method disclosed in Patent Literature 1, since direct sound and indirect sound coming from the same direction cannot be distinguished, all sounds coming from the direct sound direction are determined to be direct sounds. As a result, there is a problem that the direct sound power is overestimated (or the indirect sound power is underestimated), and the finally obtained direct ratio becomes larger than the true value.

  The present invention has been made in view of such problems, and distinguishes reverberant sounds coming from the direction of the direct sound, and estimates the direct sound power and the reverberant sound power. A sound signal emphasis device and a perspective determination device that obtain a direct-to-reverberation energy ratio (DRR) close to the value and accurately reproduce the sound signal of the sound source based on the accurate direct-ratio estimation value It is an object to provide such methods and programs.

  The acoustic signal enhancement apparatus of the present invention includes a received sound power estimation unit, a direct sound direction power estimation unit, a reverberation sound direction power estimation unit, a subtraction unit, a direct ratio calculation unit, and a target signal adjustment unit. The reception sound power estimation unit obtains a power estimation value of the frequency domain signal using a frequency domain signal obtained by converting a reception signal received by a plurality of microphones included in the microphone array into a frequency domain. The direct sound direction power estimator is a power estimation value of a direct sound direction signal obtained by performing a process of mainly passing a signal component arriving from a direct sound source direction to a frequency domain signal, or a received sound signal. Thus, the power estimation value of the direct sound direction signal obtained by converting the signal subjected to the processing of mainly passing the signal component arriving from the direct sound source direction into the frequency domain is obtained. The reverberant sound direction power estimation unit passes signal components that mainly come from other than the direct sound source direction in the same directivity shape as the processing that mainly passes signal components that come from the direct sound source direction of the direct sound direction power estimation unit. The power estimation value of the reverberant sound direction signal obtained by processing, or the signal that has been processed to pass the signal component that mainly arrives from outside the direct sound source direction to the received sound signal is converted to the frequency domain To obtain the estimated power value of the reverberation direction signal. The subtracting unit outputs a direct sound power estimated value obtained by subtracting the power estimated value of the reverberant sound direction signal from the power estimated value of the direct sound direction signal. The direct ratio calculation unit uses the power estimation value of the frequency domain signal and the power estimation value of the reverberation sound direction signal, and indicates the ratio of the direct sound power estimation value to the power estimation value of the reverberation sound direction signal. Get. The target signal adjustment unit multiplies the processing target signal obtained from the received sound signal by a gain corresponding to the direct ratio estimation value to obtain a processed signal. The gain multiplied by the processing target signal whose ratio represented by the direct ratio estimation value is larger than the predetermined threshold is larger than the gain multiplied by the processing target signal whose ratio is smaller than the predetermined threshold.

  Further, the perspective determination device of the present invention is the same as the above-described acoustic signal enhancement device, the received sound power estimation unit, the direct sound direction power estimation unit, the reverberant sound direction power estimation unit, the subtraction unit, and the direct ratio calculation And a perspective determination unit. The perspective determination unit includes a determination value corresponding to the direct ratio estimation value obtained based on the received sound signal received in a determination section including one or more frames, and more than the determination section. The direct determination in the determination section is performed by comparison determination using a plurality of reference values corresponding to the direct ratio estimation values obtained based on the received sound signal received in the reference section including a number of frames. Determine the perspective of the sound source.

  The acoustic signal emphasizing apparatus of the present invention enhances the sound signal of the sound source using the direct ratio estimation value obtained by the direct ratio estimation method proposed by the present invention. The direct ratio estimation method is a new method that focuses on the isotropic direction of arrival due to the strong diffusivity of reverberant sound. It uses two or more beamformers with the same directivity shape realized by the microphone array. In the signals coming from the direct sound direction, the direct sound and the reverberant sound are distinguished and the respective powers are correctly estimated. As a result, the accuracy of estimating the direct ratio can be improved, so that the sound signal of the sound source can be accurately emphasized.

  In addition, the perspective determination device of the present invention determines the distance of the sound source of sounds having different pronunciation times based on the direct ratio estimation value obtained by the direct ratio estimation method of the present invention. Can also make an accurate determination.

The figure which shows an example of the scene using the acoustic signal enhancement apparatus. The figure which shows the propagation path of the sound indoors. The figure which shows the relationship between direct ratio and the distance between microphones. The figure which shows the principle corresponding to each Example notionally. It is a figure which shows the two beam formers which have the same directivity shape and the main beam is directed in different directions, (a) is a beam former in which the beam is directed to the sound source direction, (b) is directed to the sound source direction. Shows the beamformer. FIG. 3 is a diagram illustrating a functional configuration example of an acoustic signal enhancement device 400 according to the first embodiment. The figure which shows the operation | movement flow of the acoustic signal enhancement apparatus 400. The figure which shows the function structural example of the process target signal production | generation part 43. FIG. The figure which shows the function structural example of the direct ratio calculation part 44. The figure which shows the function structural example of direct ratio calculation part 44 '. Schematically illustrates an example of a directional shape of each reverberation directivity forming section 4431 ₁ ~4431 _N. The figure which shows the function structural example of direct ratio calculation part 44 ''. FIG. 6 is a diagram illustrating a functional configuration example of a perspective determination device according to a second embodiment. The figure which shows the experimental condition of an effect confirmation experiment. The figure which shows the simulation result of direct ratio estimation. The figure which shows the function structural example of the direct ratio estimation apparatus 160. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are given to the same components in a plurality of drawings, and the description will not be repeated. In the following description, the symbols “記号”, “^”, etc. used in the text should be written immediately above the original character, but immediately before the character due to restrictions on the text notation. It describes. In the formula, these symbols are written in their original positions.

Prior to the description of the embodiments, the principle corresponding to each embodiment will be described.
〔principle〕
The acoustic signal emphasizing device according to the first embodiment uses a single microphone array to emphasize or suppress only sound within a specific distance range from the microphone array and collect sound of a sound source within a predetermined range. It is intended. Further, the perspective determination apparatus according to the second embodiment determines the perspective of the sound source position of the received sound signal.

  FIG. 1 illustrates a scene in which the acoustic signal enhancement device 400 according to the first embodiment is used. Assume that a small microphone array 11 is surrounded by, for example, four speakers 12 to 14 for a conference. It is assumed that a television 16, a telephone 17, and a speaker 18 for broadcasting in the hall are arranged in the conference room. In such a scene, the speakers 12 to 14 located within a predetermined distance range (within a circle indicated by a broken line) around the small microphone array 11 without picking up the voice of the in-house broadcast or the sound of the telephone. I want to pick up only the utterances.

  Therefore, in order to distinguish the distance from the microphone array to the sound source, attention is focused on the ratio of direct sound and indirect sound (also referred to as reverberation sound) included in the received sound (hereinafter referred to as direct ratio). FIG. 2 shows a sound propagation path from the sound source 21 to the microphone 22 when a microphone is placed indoors and a sound is recorded. The direct sound is a sound wave indicated by a thick solid line that directly reaches from the sound source 21 to the microphone. One reverberant sound is a sound wave indicated by a broken line that reaches the microphone 22 after the sound emitted from the sound source 21 is reflected by a wall, floor, ceiling, or the like.

  FIG. 3 shows the relationship between the direct ratio and the distance between the microphones. The horizontal axis in FIG. 3 is the distance from the microphone to the sound source, and the vertical axis is the direct ratio. In general, the indirect sound has a certain magnitude that does not depend on the distance from the microphone. In contrast to the indirect sound, the direct sound exhibits a characteristic that monotonously decreases as the distance from the microphone increases. The direct ratio obtained by dividing the direct sound by the indirect sound has a characteristic that decreases monotonously as the distance increases, as in the case of the direct sound.

  From this direct ratio, a predetermined distance range around the microphone array 11 can be estimated. Therefore, it is possible to emphasize only the acoustic signal from the desired sound source by using this direct ratio.

FIG. 4 conceptually shows the idea of the principle of direct ratio estimation according to the present invention. In general, when reverberation is sufficient, diffusivity can be assumed for reverberant sound, and it is known that reverberant sound can be modeled as sound arriving at the same magnitude from all directions when viewed from a microphone. Applying any beamformer BF1 output signal of the small microphone array 11, may be received sound reverberation direction power 23 in a predetermined directional shape D _1. Three arrows reverberation direction power 23, the magnitude of reverberation obtained by directional shape D ₁ are schematically represented.

Assuming that the position of the sound source 21 is already known, the direct sound power 25 that directly arrives at the small microphone array 11 from the sound source 21 has the directivity shape D ₀ of the beamformer BF ₀ as D _1, and its directivity. By setting the direction to the direction of the sound source 21, it is possible to receive the direct sound direction power 26 including the reverberation sound direction power having the same magnitude as the reverberation sound direction power 23.

  The direct sound power 25 can be obtained by subtracting the reverberant sound direction power 23 from the direct sound direction power 26 including the same reverberation component as the reverberant sound direction power 23. Next, this principle will be explained theoretically.

<Model of arrival of isotropic reverberation>
In the proposed method, a model considering the isotropic nature of reverberant sound is introduced. Here, an example in which the power spectral density or its estimated value is used as the power estimated value will be described, but this does not limit the present invention.

When the received sound signal of the m-th microphone of the microphone array composed of M (M ≧ 2) microphones is converted into the frequency domain by short-time Fourier transform or the like, the following frequency domain signal X ^(m) (ω, t) Is obtained.

Where ω is a frequency, H _D ^(m) (ω) is a direct sound transfer function from the sound source to the m-th microphone, and H _R ^(m) (ω) is a sound source to the m-th microphone. It is a transfer function of indirect sound, and S (ω, t) is a signal obtained by converting the sound of the sound source into the frequency domain. t is a time frame index.

  Here, it is assumed that the direct sound is coherent while the indirect sound is a diffuse sound because its main component is reverberation. That is, when attention is paid to the respective arrival directions, the direct sound arrives only from the direction of the sound source, whereas the indirect sound has a property of arriving with uniform power from all directions (hereinafter referred to as isotropic). In the proposed method, the direct ratio is obtained by estimating the direct sound power and the indirect sound power by paying attention to the difference in these arrival characteristics.

As a prerequisite, the direct sound arrival direction (hereinafter referred to as “direct sound source direction”) is known, and direct sound and indirect sound coming from any direction can be regarded as plane waves. Uncorrelated with each other. At this time, the transfer functions H _D ^(m) (ω) and H _R ^(m) (ω) of the direct sound and the indirect sound from the sound source to the m-th microphone can be expressed as follows.

Here, H _Dref (ω) is a direct sound component of the transfer function from the sound source to the reference point (referred to as “reference point”) of the microphone array, and H _{Rref, θ} (ω) is an indirect sound in the direction θ viewed from the reference point. It is an ingredient. The reference point may exist inside the microphone array, or may exist at any position on the microphone of the microphone array.

The transfer functions H _D ^(m) (ω) and H _R ^(m) (ω) of the direct sound and the indirect sound are the transfer function component from the sound source to the reference point and the propagation from the reference point to the mth microphone. It can be expressed as a phase difference component due to delay. Therefore, a microphone array input vector whose elements are frequency domain signals X ^(m) (ω, t) (mε {1,..., M}) ^→ x (ω, t) = [X ⁽¹⁾ (ω, t ,..., X ^(M) (ω, t)] ^T is expressed by the following equation. T represents transposition.

However, S _D (ω, t) = H _Dref (ω) S (ω, t), S _{R, θ} (ω, t) = H _{Rref, θ} (ω) S (ω, t). ^→ a _θ (ω) is an array manifold vector in the θ direction represented by the equation (5). Each element of the array manifold vector depends on the propagation delay τ _θ ^(m) . When direct sound and indirect sound can be regarded as plane waves, the propagation delay τ _θ ^(m) depends on the relative position and direction θ of each microphone relative to the reference point of the microphone array. For details of the array manifold vector, refer to Reference Document 1 “Taita Asano,“ Sound Array Signal Processing-Sound Source Localization / Tracking and Separation (Sound Technology Series edited by the Acoustical Society of Japan) ”, Corona Co., Ltd. Company, February 25, 2011, ISBN978-4-339-01116-6 ”, Chapter 1 (P1-26).

When an arbitrary beamformer (BF) is applied to the microphone array input, the output power spectral density (PSD) is changed to the output power spectral density (PSD) of each of the direct sound and the indirect sound shown in Equation (6). The sum of (BF) multiplied by the power gain | _Dθ (ω) | ² .

_{However, P D (ω) = E} [| S D (ω, t) | 2] t, P R, θ (ω) = E [| S R (ω, t) | 2] t, → w (ω ) Is a filter coefficient of the beamformer (BF), and R (ω) is an input of a microphone array having R _ij (ω) = E [X _i (ω, t) X _j ^* (ω, t)] _t in the ij component. It is a signal space correlation matrix. E [•] represents an expected value calculation.

<Direct ratio estimation using multiple beamformers>
In the sound field that can be assumed that the indirect sound isotropically arrives in Equation (6), the reverberant power P _R , _θ (ω) can be replaced with a constant ￣P _R (ω) that does not depend on the direction θ. The power spectral density can be expressed by equation (7).

Here, if there are two beam formers BF0 and BF1 having the same directivity shape as shown in FIG. 5 and having the main beam directed in different directions, the second term ∫ _θ | D on the right side of Equation (7) _θ (ω) | ² dθ are equal, and the output of each beamformer changes only with the first term on the right side, that is, the beamformer's power gain for direct sound.

Therefore, the output power spectral density P ₁ beamformer BF1 with its null (low point directivity sensitivity) from the output power spectral density P ₀ beamformer BF0 with its beam to the sound source direction _(omega) in the sound source direction _(omega ) Is subtracted, the direct sound power 25 can be obtained.

  Based on the above principle, reverberant sound coming directly from the sound source direction can be distinguished, and as a result, the accuracy of the direct ratio can be improved.

FIG. 6 illustrates a functional configuration example of the acoustic signal enhancement device 400 according to the first embodiment. The operation flow is shown in FIG. The acoustic signal enhancement device 400 includes a microphone array 41, a plurality of frequency domain conversion units 42 _{1 to} 42 _M , a processing target signal generation unit 43, a direct ratio calculation unit 44, a target signal adjustment unit 45, and an inverse frequency. An area conversion unit 46. Each functional configuration unit excluding the microphone array 41 is realized by a predetermined program being read into a computer including, for example, a ROM, a RAM, and a CPU, and the CPU executing the program.

Microphone array 41 is a plurality of microphones m _1, consisting of ... m _M. A plurality of frequency domain transform section 42 _1, ..., 42 _M, a plurality of microphones m _1, ... m _M received sound has been received sound signal x _m (n) are inputted, respectively, each received sound signal in the frequency domain It converts into a signal (step S42). The frequency domain converters 42 ₁ ,..., 42 _M sample the received sound signal x _m (n), for example, at a sampling frequency of 16 kHz and convert it into a digital signal, for example, 256 samples as one frame. In Step S42, discrete Fourier transform is performed to output a frequency component X _m (ω, t) (step S42). ω is a frequency, and t is a frame number. An A / D converter that converts the received sound signal x _m (n) into a digital signal is omitted.

Processing signal generating unit 43, a plurality of frequency domain transform section 42 _1, ..., generates a 42 _M signals X _m of frequency domain output (omega, t) by combining the processed signal Y (ω, t) (Step S43).

Chokkan ratio calculation unit 44, a plurality of frequency domain transform section 42 _1, ..., 42 _m signal X _m (ω, t) in the frequency domain to output Chokkan ratio estimate DRR of the received sound signals as input (omega , T) is calculated (step S44). Detailed operation of the direct ratio calculation unit 44 will be described later.

  The target signal adjustment unit 45 receives the processing target signal Y (ω, t) and the direct ratio estimated value DRR (ω, t) as input and adjusts the amplitude of the processing target signal Y (ω, t) according to the values. The processed post-process signal Z (ω, t) is generated (step S45).

The inverse frequency domain converter 46 converts the processed signal Z (ω, t) into a time domain signal z (n) (step S46). The operations from step S41 to step S46 are continued until all the sound reception signals x _m (n) are completed.

  Here, adjustment according to the value of the direct ratio estimated value DRR (ω, t) means threshold processing of DRR (ω, t) and the amplitude of the post-processing signal Z (ω, t) as the value increases. And processing such as decreasing the amplitude of the post-processing signal Z (ω, t) as the value increases. Details will be described later.

  With the above operation, noise removal is performed by the microphone array, for example, by emphasizing only sounds within a specific distance range and suppressing and collecting sounds outside the range. Hereinafter, the present invention will be described in more detail by showing more specific functional configuration examples of the respective units.

[Processing signal generator]
FIG. 8 shows a more specific functional configuration example of the processing target signal generation unit 43. The processing target signal generation unit 43 includes a plurality of weight multiplication units 431 _{1 to} 431 _M and an addition unit 432. The plurality of weight multiplying means 431 _{1 to} 431 _M are respectively frequency components X ₁ (ω, t),..., X _M (ω) of a plurality of received signals x _m (n) received by M microphones. , T) is multiplied by a weighting factor w _m (ω).

For the weights used in the weight multiplication means 431 _{1 to} 431 _M , for example, when M microphones are omnidirectional, by setting w _m = 1 / M, all frequency components X ₁ (ω, t), .., X _M (ω, t) is averaged to stabilize the processing target signal Y (ω, t). Also, when M microphones have directivity, use only a specific microphone signal by setting w ₁ = 1, w _m = 0 (m = {2,..., M}). Can do. For example, if the filter coefficient of the weight beamforming is used by using a method described in Reference Document 2 “Oga, Yamazaki, Kanada,“ Sound System and Digital Signal Processing ”published by the Institute of Electronics, Information and Communication Engineers” An arbitrary directivity can be formed by the microphone array.

The adding means 432 adds all the frequency components X ₁ (ω, t),..., X _M (ω, t) multiplied by the weights, and outputs a processing target signal Y (ω, t).

  A microphone may be installed separately from the microphone array at a position close to the sound source without using the adding means, and the collected sound signal of the installed microphone may be used as the processing target signal Y (ω, t).

(Direct ratio calculation section)
FIG. 9 shows a functional configuration example of the direct ratio calculation unit 44. The direct ratio calculation unit 44 includes a received sound power estimation unit 441, a direct sound direction power estimation unit 442, a reverberation sound direction power estimation unit 443, a subtraction unit 444, and a direct ratio calculation unit 445.

The reception sound power estimation unit 441 converts frequency reception signals received by a plurality of microphones included in the microphone array 41 into frequency domain signals X ₁ (ω, t),..., X _M Using (ω, t), a power estimation value of the frequency domain signal corresponding to the received sound signal is generated and output. This power estimated value is a power estimated value of the frequency domain signal X _m (ω, t) corresponding to any one microphone m (mε {1,..., M}) as shown in the equation (9). Alternatively, as in Expression (10), the power estimation values of the frequency domain signals X ₁ (ω, t),..., X _M (ω, t) may be weighted and averaged. In the first embodiment, the power spectral density P _{X, L} (ω) is obtained as the power estimation value of the frequency domain signal corresponding to the received sound signal.

However, L is the number of frames, and α _m is a non-negative weight to the microphone m set so as to satisfy the equation (11). E [•] represents an expected value calculation.

The direct sound direction power estimation unit 442 is obtained by performing a process of passing only the signal component coming from the direct sound source direction with respect to the frequency domain signals X ₁ (ω, t),..., X _M (ω, t). Obtained by converting the power estimation value P _DD (ω) of the direct sound direction signal or the signal obtained by performing the process of passing only the signal component coming from the direct sound source direction to the received sound signal into the frequency domain. A power estimate value P _DD (ω) of the direct sound direction signal is obtained. The power P _DD (ω) of the direct sound direction signal is the same as P ₀ (ω) in equation (8).

  The direct sound direction power estimation unit 442 includes a directivity forming unit 4421 and a power estimation unit 4422. The directivity forming unit 4421 forms directivity so that a directional beam is directed in a predetermined direction, and outputs a signal that has passed the directivity. The directivity of the directivity forming unit 4421 is set so that the main beam having directivity faces the direct sound direction. As a method of directivity formation, for example, the delayed sum beam described in Reference Document 1 (Taro Asano, “Sound Array Signal Processing-Sound Source Localization / Tracking and Separation” Corona, pp. 70-79)). A method such as forming can be used.

When the output of the directivity forming unit 4421 is expressed as Y _BF (ω, t), the power estimation value P _DD (ω) of the direct sound direction signal output from the power estimation unit 4422 is obtained by Expression (12).

Further, the output power spectral density of the power estimation value P _DD (ω) of the direct sound direction signal is expressed by Expression (13).

Here, | D _0θ (ω) | ² corresponds to the power gain of the beam former _{BF 0} described in FIG.

  The reverberant sound direction power estimation unit 443 has the same directivity shape as the process of mainly passing the signal component arriving from other than the direct sound source direction through the signal component arriving from the direct sound source direction of the direct sound direction power estimation unit 442. Converts the estimated power of the reverberant sound direction signal obtained by passing the signal, or the signal that has been processed to pass the signal component that mainly arrives from outside the sound source direction to the received sound signal into the frequency domain. Thus, the power estimate value of the reverberation direction signal is obtained.

  Ideally, the reverberant sound direction power estimation unit 443 includes a reverberation directivity forming unit 4431 and a reverberation power estimation unit 4432. The directivity of the reverberation directivity forming unit 4431 is set so that the directivity main beam avoids the direct sound direction. The directivity shape is set to be the same as that of the directivity forming portion 4421. The directivity shapes of the reverberation directivity forming unit 4431 and the directivity forming unit 4421 are desirably set to be the same as much as possible. The setting of the directivity shape can be easily realized by the prior art. The estimation of the direction of the sound source is described in, for example, Chapter 7.2 of Reference Document 2 “Oga, Yamazaki, Kanada,“ Acoustic System and Digital Signal Processing ”published by IEICE.

The reverberation power estimation unit 4432 receives the reverberant sound received so as to avoid the direct sound direction and outputs a power estimate value P _RD (ω) of the reverberant sound direction signal (Equation 14). Since the power estimation value P _RD (ω) of the reverberant sound direction signal is received so as to avoid the direct sound direction, by setting | D _{1, θD} | ² << _1, the direct sound component | D _{0, θ} (ω) | ² P _D (ω) is sufficiently small.

Here, | D ₁ (ω) | ² corresponds to the power gain of the beam former BF1 described in FIG.

The subtracting unit 444 uses the power estimation value P _RD (ω) of the reverberation sound direction signal output from the reverberation power estimation unit 4432 from the power estimation value P _DD (ω) of the direct sound direction signal output from the direct sound direction power estimation unit 442. ) Is subtracted from the direct sound power estimated value ^ P _D (ω) (formula (15)).

The denominator of the equation (15) normalizes the direct sound power estimated value ^ P _D (ω) by the difference in power gain between the beamformers (BF) of the directivity forming unit 4421 and the reverberant directivity forming unit 4431. It is a term of.

The direct ratio calculation unit 445 uses the power spectral density P _{X, L} (ω) and the direct sound power estimated value ^ P _D (ω) output from the received sound power estimating part 441, and uses the direct sound power estimated value ^ P _D. A direct ratio estimated value DRR (ω), which is the ratio of the power of (ω) and the power estimated value of the reverberant sound direction signal, is obtained (equation (16)).

  Further, when the received sound power output from the received sound power estimation unit 441 is expressed by the equation (9) corresponding to any one microphone m (mε {1,..., M}), the direct ratio Can also be estimated by equation (17).

  Further, the direct ratio can be estimated by the equations (18) and (19) as the direct ratio independent of the frequency. In addition, since it is the value calculated | required for every frame number L, it describes with DRR ((omega)), However, The value calculated | required for every frequency for every frame is described with DRR ((omega), t).

  The direct ratio estimation method described above is a new method that pays attention to the fact that reverberant sound is isotropically arrives at the microphone array since it is a highly diffuse signal. By using two beamformers with the same directional shape realized by a microphone array, a direct sound component and an indirect sound component are correctly separated by obtaining a signal including direct sound and reverberation sound and a signal including only reverberation sound. As a result, the estimation accuracy of the direct ratio can be improved.

  The expressions (16), (17), (18), and (19) may be direct ratio estimated values DRR that are not expressed in decibels as follows.

[Modification 1]
FIG. 10 shows a functional configuration example of a direct ratio calculation unit 44 ′ in which the functional configuration of the reverberation sound direction power estimation unit 443 of the direct ratio calculation unit 44 is modified. Chokkan ratio calculating unit 44 'obtains the reverberation direction power _{P RD} (omega), a plurality (two or more) orientation of the reverberation sound direction power _{P RD1} an _{(omega) to P RDN} (omega) On average It is what I did.

The reverberation sound direction power estimation unit 443 ′ of the direct ratio calculation unit 44 ′ includes two or more reverberation directivity forming units 4431 _{1 to} 4431 _N , two or more reverberation power estimation units 4432 _{1 to} 4432 _N , and reverberation. It differs from the direct ratio calculation unit 44 in that a directional power calculation unit 4433 is provided. The direction of the main beam of the beam former of the reverberation directivity forming unit 4431 ₁ is, for example, the direction θ ₁ from the reference point. Direction of the main beam beamformer reverberation directivity forming section 4431 ₂ is the direction theta _1, the direction of the main beam beamformer reverberation directivity forming section 4431 _N is the direction theta _N.

FIG. 11 schematically shows the directivity shapes of the reverberation directivity forming units 4431 _{1 to} 4431 _N. The directivity shapes of the reverberation directivity forming units 4431 _{1 to} 4431 _N are different only in the direction θ of the main beam and have the same shape. Reverberation sound power estimation values P _RD1 (ω) to P in each directivity direction from the signals that have passed through the directivities of the respective reverberation directivity formation units 4431 _{1 to} 4431 _N by the reverberation power estimation units 44321 to 4432N connected thereto. _RDN (ω) is determined.

The reverberation direction power calculation unit 4433 calculates the reverberation sound direction power P _RD (ω) by performing a weighted average (Expression 20) on the plurality of power estimation values P _RD1 (ω) to P _RDN (ω).

However, β _n is a non-negative weighting factor and is set in advance so as to satisfy the equation (21). Since the reverberant sound direction power P _RD (ω) obtained in this way is a value obtained by averaging the reverberant sound direction powers in a plurality of directions, the accuracy can be improved. As a result, the accuracy of the direct ratio estimation value DRR (ω) can be improved.

[Modification 2]
FIG. 12 shows a functional configuration example of the direct ratio calculation unit 44 ″ obtained by changing the functional configuration of the reverberation sound direction power estimation unit 443 of the direct ratio calculation unit 44. The direct ratio calculation unit 44 ″ is a directivity generator. The direction of the main beam of the beam former of the unit 4421 and the reverberation directivity forming unit 4431 can be automatically set.

The direct ratio calculation unit 44 ″ is different from the direct ratio calculation unit 44 in that it includes a sound source direction estimation unit 446 and a beam former generation unit 447. The sound source direction estimation unit 446 is included in the microphone array 41. The direction of the sound source is estimated by using as input the frequency domain signals X ₁ (ω, t),..., X _M (ω, t) obtained by converting the received signals received by a plurality of microphones into the frequency domain. The direction of the sound source can be obtained by a conventional technique from the phase difference of the frequency domain signals X ₁ (ω, t),..., X _M (ω, t), for example. .

The beamformer generation unit 447 receives a sound source direction signal, generates a beamformer BF0 having a main beam in the sound source direction, and a beamformer BF1 in which the main beam is set so as to avoid the sound source direction. The former BF0 is output to the direct sound direction power estimating unit 442, and the beam former BF1 is output to the reverberant sound direction power estimating unit 443. The directivity forming unit 4421 of the direct sound direction power estimating unit 442 applies the beamformer BF0 and outputs the output signal Y _BF (ω, t) described above. The reverberant sound direction power estimation unit 443 outputs the reverberant sound direction power _PRD (ω) by applying the beam former BF1.

  As described above, the direct ratio calculation unit 44 ″ can automatically set the directivity shapes of the direct sound direction power estimation unit 442 and the reverberant sound direction power estimation unit 443. As described above, the direct ratio calculation unit 44, The operation of 44 ′, 44 ″ has been described with an example of operating in the frequency domain. However, the technical idea of the present invention including the modification can be applied to the operation in the time domain as it is. It is also possible to apply the idea of the direct ratio calculation unit 44 ″ to the direct ratio calculation unit 44 ′.

[Target signal adjustment section]
The target signal adjustment unit 45 receives the processing target signal Y (ω, t) and the direct ratio estimated value DRR (ω, t) as input, and processes the target signal Y according to the direct ratio estimated value DRR (ω, t). A post-processing signal Z (ω, t) in which the amplitude of (ω, t) is adjusted is generated and output. In other words, the target signal adjustment unit 45 multiplies the processing target signal Y (ω, t) by a gain (filter coefficient) corresponding to the direct ratio estimated value DRR (ω, t), thereby processing the processed signal Z (ω , T) is generated and output (step S45).

  The magnitude of the gain determined according to the direct ratio estimated value DRR depends on the distance range from the microphone array 41 and the sound emitted from the direct sound source. For example, when the sound emitted from the direct sound source close to the microphone array 41 is further emphasized, the ratio of the power estimate value of the direct sound to the power estimate value of the indirect sound represented by the direct ratio estimate value DRR is the first value. In some cases, the gain multiplied by the processing target signal is set to be larger than the gain multiplied by the processing target signal when the ratio is a second value smaller than the first value. For example, when the sound emitted from a direct sound source far from the microphone array 41 is further emphasized, the ratio of the direct sound power estimated value to the indirect sound power estimated value represented by the direct ratio estimated value DRR is the first value. In some cases, the gain G (ω, t) multiplied by the processing target signal is made smaller than the gain multiplied by the processing target signal when the ratio is a second value smaller than the first value.

  The target signal adjustment unit 45 can be configured by, for example, a filter coefficient calculation unit 451 and a multiplication unit 452 (FIG. 6). The filter coefficient calculation unit 45 calculates and outputs a filter coefficient G (ω, t) with the direct ratio estimated value DRR (ω, t) as an input. For the calculation of the filter coefficient G (ω, t), for example, a binary filter using a threshold value as shown in equations (22) and (23) is used.

The threshold Th ₁ can arbitrary value set between the minimum and maximum values of Chokkan ratio estimate DRR (ω, t). The sound quality is improved when the threshold Th ₁ is brought close to the minimum value (0). Noise suppression effect is brought close to the threshold Th ₁ to the maximum value in the opposite order to increase but deteriorates the sound quality becomes large distortion of the received sound signal.

Thus, the threshold Th ₁ has a trade-off relationship between the sound quality and the noise suppression. Therefore, the threshold Th ₁ is determined empirically according to the purpose of use in consideration of this trade-off relationship.

Further, when calculating the filter coefficient G (ω, t), as shown in the equations (24) and (25), if the time frequency band in which the direct ratio estimated value falls below the threshold Th ₂ is emphasized, a specific frequency Sound sources farther than the distance range can be emphasized.

  In addition, although the binary filter of 0 or 1 was mentioned as an example of the filter coefficient G (ω, t), the filter coefficient G (ω, t) does not necessarily have to be 0 and 1, for example, 0.1 And a sufficiently different value such as 0.9.

  Further, a real number of 1 or more may be set for the filter coefficient G (ω, t). That is, the gain G (ω, t) for amplifying the processing target signal Y (ω, t) may be determined. Further, a gain G (ω, t) (for example, a value of 0.1 or less) that largely suppresses the processing target signal Y (ω, t) may be determined. Further, instead of determining the gain G (ω, t) by threshold determination, the direct ratio estimated value or its function value may be used as the gain G (ω, t). For example, the gain G (ω, t) may be determined as in the following formulas (26) to (29).

  However, F is a function such as a monotonically increasing function or a monotonically decreasing function.

  The multiplication coefficient 452 multiplies the processing target signal Y (ω, t) by the filter coefficient G (ω, t) obtained in this way, and the processed signal Z (ω, t) = G (ω, t) · Y (ω, t) is generated. Therefore, the post-processing signal Z (ω, t) can be composed of only the processing target signal Y (ω, t) having a large direct ratio estimate value DRR (ω, t). That is, only the direct sound can be extracted.

As a second embodiment, a perspective determination device 120 that determines the perspective of a sound source using the direct ratio estimated value DRR (ω, t) described in the first embodiment will be described. FIG. 13 shows a functional configuration example of the perspective determination device 120. The perspective determination device 120 includes a microphone array 41, a plurality of frequency domain conversion units 41 _{1 to} 41 _m , a direct ratio calculation unit 44, and a perspective determination unit 121. The microphone array 41, the plurality of frequency domain conversion units 41 _{1 to} 41 _m, and the direct ratio calculation unit 44 are the same as those of the noise removal device 400. The distance determination device 120 is also realized by a predetermined program being read into a computer including, for example, a ROM, a RAM, and a CPU, and the CPU executing the program.

  The perspective determination device 120 determines whether a sound source of a sound received at a certain time is far or near when sound sources at a plurality of different distances sound at different times. The perspective determination unit 121 included in the perspective determination device 120 includes a frequency averaging unit 1210, a storage unit 1211, and a determination unit 1212.

  The perspective determination unit 121 includes a determination value corresponding to the direct ratio estimation value obtained based on the received sound signal received in the determination section including one or more frames, and a larger number of frames than the determination section. The perspective determination of the direct sound source in the determination section is performed by comparison determination using reference values corresponding to a plurality of direct ratio estimation values obtained based on the received sound signal received in the reference section.

The frequency averaging means 1210 receives the direct ratio estimated value DRR (ω, t) as an input, averages the value in the frequency direction, and outputs a frequency average direct ratio estimated value ￣E _t (formula (30)).

Here, K is the total number of frequency bins of the Fourier transform performed by the frequency domain transform units 42 _{1 to} 42 _M.

The accumulating unit 1211 accumulates the frequency average direct ratio estimation value ￣E _t for the past L time frames and outputs the comparison target direct ratio estimate value ^ E. Compared Chokkan ratio estimate ^ The E, for example, stored frequency mean Chokkan ratio estimates the average value of ¯e _t ^ and ^{_{E = 1 / LΣ t L ¯E}} t, minimum and average values of the maximum value E ^ = 1/2 (max￣E _t + min￣E _t ) or the like is used.

Determination means 1212, a frequency averaging Chokkan ratio equivalent value ¯e _t, compares the comparison Chokkan ratio equivalent value ^ E, that is close distance distance determination result Y _l when the ¯E _{t> ^} E the representative example 1, and outputs the ¯E _l <^ 0 example indicates that the distance is far in distance determination result Y _t is the time of E. The distance determination result Y _t is the last received sound signals of the past L time period is either a sound from relatively close sound source or those indicating which sounds from a relatively distant sound source.

By using this distance determination result Y _t , it is possible to distinguish the sequentially received sound signal based on the distance between the microphone and the sound source. That is, sounds from a plurality of sound sources can be selected according to the distance from the microphone.

〔Experimental result〕
In order to confirm the effect of the present invention, a simulation experiment using a mirror image method was performed.

FIG. 14 shows the simulation conditions. FIG. 14 is a plan view, assuming a room having a width of 4 m, a depth of 6 m, and a height of 2.7 m. The wall sound absorption coefficient was set to α = 0.05 (reverberation time T ₆₀ = 1.8 seconds). A microphone array in which eight microphones were arranged in a circle was used, and the height of the reference point was 1.5 m. The height of the sound source was also 1.5 m.

FIG. 15 shows a result of comparison between the _actual DRR _actual value (□) estimated from the impulse response, the present invention (▽), and the conventional method (◯) under these conditions. The DRR (▽) estimated by the method of the present invention is closer to the actually measured value DRR _actual (□) than the conventional method, and is improved by about 3 dB particularly when the sound source is far away.

  In general, the power of the indirect component is constant regardless of the distance of the sound source, whereas the power of the direct component is inversely proportional to the square of the distance. For this reason, in the case of a distant sound source, the power of the direct component is smaller than that of the indirect component, and even if the error included in the estimated direct component is small, the DRR estimation result is greatly affected. According to the method of the present invention, the power of the indirect sound is obtained by suppressing the influence of the signal arriving from the sound source direction as much as possible by the directivity control of the microphone array, so that it is possible to perform the estimation with higher accuracy and the DRR to the sound source farther away. Can be estimated correctly.

  As described above, the new direct ratio estimation method of the present invention is a new method that assumes that the reverberant sound is isotropically arrives at the microphone array since it is a highly diffuse signal. The sound source direction by the beamformer with the same directional shape realized by the microphone array and the main beam direction set directly to the sound source direction, and the beamformer set the main beam direction to avoid the direct sound source direction The direct component and the indirect component coming from can be correctly separated, and as a result, the accuracy of the estimate of the direct ratio can be improved.

In the above description, the direct ratio estimation method of the present invention has been described as an example incorporated in the acoustic signal enhancement device 400 or the perspective determination device 130. However, as shown in FIG. 16, the direct ratio estimation method of the present invention. However, it may be configured as the direct ratio estimation device 160 that realizes only the above. In that case, the direct ratio estimation device 160 can be configured by the microphone array 41, a plurality of frequency domain converters 42 _{1 to} 42 _M, and the direct ratio calculator 44.

  In addition, although the example expressed in decibel as the direct ratio estimated value DRR is shown in the equations (16) to (19), it goes without saying that the direct ratio estimated value may be obtained by the ratio of the power spectral density. The direct ratio estimation value may be obtained by multiplying the DRR value represented by the above formula by any constant, or the constant may be multiplied by the reciprocal of the DRR value represented by the above formula. It is good also as a direct ratio estimated value. The constant may be a monotonically increasing function value. That is, the direct ratio estimated value DRR of the present invention is not limited to that expressed by the above formulas (16) to (19).

Note that the processes described in the above method and apparatus are not only executed in time series according to the order of description, but may also be executed in parallel or individually as required by the processing capability of the apparatus that executes the processes. Good.

  Further, when the processing means in the above apparatus is realized by a computer, the processing contents of functions that each apparatus should have are described by a program. Then, by executing this program on the computer, the processing means in each apparatus is realized on the computer.

  The program describing the processing contents can be recorded on a computer-readable recording medium. As the computer-readable recording medium, for example, any recording medium such as a magnetic recording device, an optical disk, a magneto-optical recording medium, and a semiconductor memory may be used. Specifically, for example, as a magnetic recording device, a hard disk device, a flexible disk, a magnetic tape or the like, and as an optical disk, a DVD (Digital Versatile Disc), a DVD-RAM (Random Access Memory), a CD-ROM (Compact Disc Read Only). Memory), CD-R (Recordable) / RW (ReWritable), etc., magneto-optical recording medium, MO (Magneto Optical disc), etc., semiconductor memory, EEP-ROM (Electronically Erasable and Programmable-Read Only Memory), etc. Can be used.

  The program is distributed by selling, transferring, or lending a portable recording medium such as a DVD or CD-ROM in which the program is recorded. Further, the program may be distributed by storing the program in a recording device of a server computer and transferring the program from the server computer to another computer via a network.

  Each means may be configured by executing a predetermined program on a computer, or at least a part of these processing contents may be realized by hardware.

Claims (9)

A received sound power estimation unit that obtains a power estimation value of the frequency domain signal using a frequency domain signal obtained by converting a received sound signal received by a plurality of microphones included in the microphone array into a frequency domain;
The power estimation value of the direct sound direction signal obtained by performing the process of mainly passing the signal component arriving from the direct sound source direction with respect to the frequency domain signal, or the direct sound source direction with respect to the received signal A direct sound direction power estimation unit that obtains a power estimation value of a direct sound direction signal obtained by converting the signal that has been processed to pass through the signal component mainly into the frequency domain;
It is obtained by performing a process of passing signal components mainly coming from other than the direct sound source direction with the same directivity shape as the process of mainly passing the signal components coming from the direct sound source direction of the direct sound direction power estimation unit. It is possible to convert the power estimation value of the reverberant sound direction signal obtained or the signal obtained by performing the process of passing the signal component mainly coming from outside the direct sound source direction to the received sound signal into the frequency domain. A reverberant sound direction power estimation unit for obtaining a power estimate of a reverberant sound direction signal;
A subtracting unit that outputs a direct sound power estimated value obtained by subtracting a power estimated value of the reverberant sound direction signal from a power estimated value of the direct sound direction signal;
Using the power estimation value of the frequency domain signal and the power estimation value of the reverberation sound direction signal, the direct ratio to obtain the direct ratio estimation value representing the ratio of the power estimation value of the direct sound to the power estimation value of the reverberation sound direction signal A ratio calculator;
A target signal adjusting unit for obtaining a post-processing signal by multiplying a processing target signal obtained from the received sound signal by a gain according to the direct ratio estimation value;
The gain multiplied by the processing target signal for which the ratio represented by the direct ratio estimation value is larger than a predetermined threshold is larger than the gain multiplied by the processing target signal for which the ratio is smaller than the predetermined threshold. , Sound signal enhancement device. A received sound power estimation unit that obtains a power estimation value of the frequency domain signal using a frequency domain signal obtained by converting a received sound signal received by a plurality of microphones included in the microphone array into a frequency domain;
The power estimation value of the direct sound direction signal obtained by performing the process of mainly passing the signal component arriving from the direct sound source direction with respect to the frequency domain signal, or the direct sound source direction with respect to the received signal A direct sound direction power estimation unit that obtains a power estimation value of a direct sound direction signal obtained by converting the signal that has been processed to pass through the signal component mainly into the frequency domain;
It is obtained by performing a process of passing signal components mainly coming from other than the direct sound source direction with the same directivity shape as the process of mainly passing the signal components coming from the direct sound source direction of the direct sound direction power estimation unit. It is possible to convert the power estimation value of the reverberant sound direction signal obtained or the signal obtained by performing the process of passing the signal component mainly coming from outside the direct sound source direction to the received sound signal into the frequency domain. A reverberant sound direction power estimation unit for obtaining a power estimate of a reverberant sound direction signal;
A subtracting unit that outputs a direct sound power estimated value obtained by subtracting a power estimated value of the reverberant sound direction signal from a power estimated value of the direct sound direction signal;
Using the power estimation value of the frequency domain signal and the power estimation value of the reverberation sound direction signal, the direct ratio to obtain the direct ratio estimation value representing the ratio of the power estimation value of the direct sound to the power estimation value of the reverberation sound direction signal A ratio calculator;
A target signal adjusting unit for obtaining a post-processing signal by multiplying a processing target signal obtained from the received sound signal by a gain according to the direct ratio estimation value;
The gain multiplied by the processing target signal for which the ratio represented by the direct ratio estimation value is larger than a predetermined threshold is smaller than the gain multiplied by the processing target signal for which the ratio is smaller than the predetermined threshold. , Sound signal enhancement device. A received sound power estimation unit that obtains a power estimation value of the frequency domain signal using a frequency domain signal obtained by converting a received sound signal received by a plurality of microphones included in the microphone array into a frequency domain;
The power estimation value of the direct sound direction signal obtained by performing the process of mainly passing the signal component arriving from the direct sound source direction with respect to the frequency domain signal, or the direct sound source direction with respect to the received signal A direct sound direction power estimation unit that obtains a power estimation value of a direct sound direction signal obtained by converting the signal that has been processed to pass through the signal component mainly into the frequency domain;
It is obtained by performing a process of passing signal components mainly coming from other than the direct sound source direction with the same directivity shape as the process of mainly passing the signal components coming from the direct sound source direction of the direct sound direction power estimation unit. Obtained by converting the received reverberation direction signal power estimate value, or a signal obtained by performing a process of passing a signal component mainly coming from outside the direct sound source direction to the received sound signal into the frequency domain. A reverberant sound direction power estimation unit for obtaining a power estimate of a reverberant sound direction signal;
A subtracting unit that outputs a direct sound power estimated value obtained by subtracting a power estimated value of the reverberant sound direction signal from a power estimated value of the direct sound direction signal;
Using the power estimation value of the frequency domain signal and the power estimation value of the reverberation sound direction signal, the direct ratio to obtain the direct ratio estimation value representing the ratio of the power estimation value of the direct sound to the power estimation value of the reverberation sound direction signal A ratio calculator;
Using the direct ratio estimate, having a perspective determination unit that performs perspective determination of the direct sound source and obtains a perspective determination result,
The direct ratio estimation value is obtained based on the received sound signal received in a frame that is a predetermined time interval,
The perspective determination unit includes a determination value corresponding to the direct ratio estimation value obtained based on the received sound signal received in a determination section including one or more frames, and more than the determination section. The direct determination in the determination section is performed by comparison determination using a plurality of reference values corresponding to the direct ratio estimation values obtained based on the received sound signal received in the reference section including a number of frames. A perspective determination device that performs perspective determination of a sound source. A received sound power estimation unit that obtains a power estimation value of the frequency domain signal using a frequency domain signal obtained by converting a received sound signal received by a plurality of microphones included in the microphone array into a frequency domain;
The power estimation value of the direct sound direction signal obtained by performing the process of mainly passing the signal component arriving from the direct sound source direction with respect to the frequency domain signal, or the direct sound source direction with respect to the received signal A direct sound direction power estimation unit that obtains a power estimation value of a direct sound direction signal obtained by converting the signal that has been processed to pass through the signal component mainly into the frequency domain;
It is obtained by performing a process of passing signal components mainly coming from other than the direct sound source direction with the same directivity shape as the process of mainly passing the signal components coming from the direct sound source direction of the direct sound direction power estimation unit. It is possible to convert the power estimation value of the reverberant sound direction signal obtained or the signal obtained by performing the process of passing the signal component mainly coming from outside the direct sound source direction to the received sound signal into the frequency domain. A reverberant sound direction power estimation unit for obtaining a power estimate of a reverberant sound direction signal;
A subtracting unit that outputs a direct sound power estimated value obtained by subtracting a power estimated value of the reverberant sound direction signal from a power estimated value of the direct sound direction signal;
Using the power estimation value of the frequency domain signal and the power estimation value of the reverberation sound direction signal, the direct ratio to obtain the direct ratio estimation value representing the ratio of the power estimation value of the direct sound to the power estimation value of the reverberation sound direction signal A ratio calculator;
A target signal adjusting unit for obtaining a post-processing signal by multiplying a processing target signal obtained from the received sound signal by a gain according to the direct ratio estimation value;
The gain multiplied by the processing target signal when the ratio represented by the direct ratio estimation value is a first value is the processing target signal when the ratio is a second value smaller than the first value. An acoustic signal emphasizing device that is larger than the gain multiplied by. A received sound power estimation unit that obtains a power estimation value of the frequency domain signal using a frequency domain signal obtained by converting a received sound signal received by a plurality of microphones included in the microphone array into a frequency domain;
The power estimation value of the direct sound direction signal obtained by performing the process of mainly passing the signal component arriving from the direct sound source direction with respect to the frequency domain signal, or the direct sound source direction with respect to the received signal A direct sound direction power estimation unit that obtains a power estimation value of a direct sound direction signal obtained by converting the signal that has been processed to pass through the signal component mainly into the frequency domain;
It is obtained by performing a process of passing signal components mainly coming from other than the direct sound source direction with the same directivity shape as the process of mainly passing the signal components coming from the direct sound source direction of the direct sound direction power estimation unit. It is possible to convert the power estimation value of the reverberant sound direction signal obtained or the signal obtained by performing the process of passing the signal component mainly coming from outside the direct sound source direction to the received sound signal into the frequency domain. A reverberant sound direction power estimation unit for obtaining a power estimate of a reverberant sound direction signal;
A subtracting unit that outputs a direct sound power estimated value obtained by subtracting a power estimated value of the reverberant sound direction signal from a power estimated value of the direct sound direction signal;
Using the power estimation value of the frequency domain signal and the power estimation value of the reverberation sound direction signal, the direct ratio to obtain the direct ratio estimation value representing the ratio of the power estimation value of the direct sound to the power estimation value of the reverberation sound direction signal A ratio calculator;
A target signal adjusting unit for obtaining a post-processing signal by multiplying a processing target signal obtained from the received sound signal by a gain according to the direct ratio estimation value;
The gain multiplied by the processing target signal when the ratio represented by the direct ratio estimation value is a first value is the processing target signal when the ratio is a second value smaller than the first value. An acoustic signal emphasizing device that is smaller than the gain multiplied by. A received sound power estimation step for obtaining a power estimation value of the frequency domain signal using a frequency domain signal obtained by converting a received sound signal received by a plurality of microphones included in the microphone array into a frequency domain;
The power estimation value of the direct sound direction signal obtained by performing the process of mainly passing the signal component arriving from the direct sound source direction with respect to the frequency domain signal, or the direct sound source direction with respect to the received signal Direct sound direction power estimation step for obtaining a power estimation value of the direct sound direction signal obtained by converting the signal that has been processed to pass through the signal component mainly into the frequency domain;
It is obtained by performing a process of passing signal components mainly coming from other than the direct sound source direction with the same directivity shape as the process of mainly passing the signal components coming from the direct sound source direction of the direct sound direction power estimation unit. It is possible to convert the power estimation value of the reverberant sound direction signal obtained or the signal obtained by performing the process of passing the signal component mainly coming from outside the direct sound source direction to the received sound signal into the frequency domain. A reverberant sound direction power estimating step for obtaining a power estimate of the reverberant sound direction signal;
A subtracting step for outputting a direct sound power estimated value obtained by subtracting a power estimated value of the reverberant sound direction signal from a power estimated value of the direct sound direction signal;
Using the power estimation value of the frequency domain signal and the power estimation value of the reverberation sound direction signal, the direct ratio to obtain the direct ratio estimation value representing the ratio of the power estimation value of the direct sound to the power estimation value of the reverberation sound direction signal A ratio calculating step;
A target signal adjustment step of obtaining a post-processing signal by multiplying a processing target signal obtained from the sound reception signal by a gain according to the direct ratio estimation value;
The gain multiplied by the processing target signal for which the ratio represented by the direct ratio estimation value is larger than a predetermined threshold is larger than the gain multiplied by the processing target signal for which the ratio is smaller than the predetermined threshold. Sound signal enhancement method. A received sound power estimation step for obtaining a power estimation value of the frequency domain signal using a frequency domain signal obtained by converting a received sound signal received by a plurality of microphones included in the microphone array into a frequency domain;
The power estimation value of the direct sound direction signal obtained by performing the process of mainly passing the signal component arriving from the direct sound source direction with respect to the frequency domain signal, or the direct sound source direction with respect to the received signal Direct sound direction power estimation step for obtaining a power estimation value of the direct sound direction signal obtained by converting the signal that has been processed to pass through the signal component mainly into the frequency domain;
It is obtained by performing a process of passing signal components mainly coming from other than the direct sound source direction with the same directivity shape as the process of mainly passing the signal components coming from the direct sound source direction of the direct sound direction power estimation unit. It is possible to convert the power estimation value of the reverberant sound direction signal obtained or the signal obtained by performing the process of passing the signal component mainly coming from outside the direct sound source direction to the received sound signal into the frequency domain. A reverberant sound direction power estimating step for obtaining a power estimate of the reverberant sound direction signal;
A subtracting step for outputting a direct sound power estimated value obtained by subtracting a power estimated value of the reverberant sound direction signal from a power estimated value of the direct sound direction signal;
Using the power estimation value of the frequency domain signal and the power estimation value of the reverberation sound direction signal, the direct ratio to obtain the direct ratio estimation value representing the ratio of the power estimation value of the direct sound to the power estimation value of the reverberation sound direction signal A ratio calculating step;
A target signal adjustment step of obtaining a post-processing signal by multiplying a processing target signal obtained from the sound reception signal by a gain according to the direct ratio estimation value;
The gain multiplied by the processing target signal for which the ratio represented by the direct ratio estimation value is larger than a predetermined threshold is smaller than the gain multiplied by the processing target signal for which the ratio is smaller than the predetermined threshold. Sound signal enhancement method. A received sound power estimation step for obtaining a power estimation value of the frequency domain signal using a frequency domain signal obtained by converting a received sound signal received by a plurality of microphones included in the microphone array into a frequency domain;
The power estimation value of the direct sound direction signal obtained by performing the process of mainly passing the signal component arriving from the direct sound source direction with respect to the frequency domain signal, or the direct sound source direction with respect to the received signal Direct sound direction power estimation step for obtaining a power estimation value of the direct sound direction signal obtained by converting the signal that has been processed to pass through the signal component mainly into the frequency domain;
It is obtained by performing a process of passing signal components mainly coming from other than the direct sound source direction with the same directivity shape as the process of mainly passing the signal components coming from the direct sound source direction of the direct sound direction power estimation unit. Obtained by converting the received reverberation direction signal power estimate value, or a signal obtained by performing a process of passing a signal component mainly coming from outside the direct sound source direction to the received sound signal into the frequency domain. A reverberant sound direction power estimating step for obtaining a power estimate of the reverberant sound direction signal;
A subtracting step for outputting a direct sound power estimated value obtained by subtracting a power estimated value of the reverberant sound direction signal from a power estimated value of the direct sound direction signal;
Using the power estimation value of the frequency domain signal and the power estimation value of the reverberation sound direction signal, the direct ratio to obtain the direct ratio estimation value representing the ratio of the power estimation value of the direct sound to the power estimation value of the reverberation sound direction signal A ratio calculating step;
Using the direct ratio estimation value, having a perspective determination step of performing perspective determination of the direct sound source to obtain a perspective determination result,
The direct ratio estimation value is obtained based on the received sound signal received in a frame that is a predetermined time interval,
The perspective determination step includes a determination value corresponding to the direct ratio estimation value obtained based on the received sound signal received in a determination section including one or more frames, and more than the determination section. The direct determination in the determination section is performed by comparison determination using a plurality of reference values corresponding to the direct ratio estimation values obtained based on the received sound signal received in the reference section including a number of frames. A perspective determination method for determining the perspective of a sound source.   A program for causing a computer to function as the acoustic signal enhancement device according to claim 1 or 2, the perspective determination device according to claim 3, or the acoustic signal enhancement device according to claim 4 or 5.

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