JP6063890B2 - Conversion device - Google Patents

Description

  The present invention relates to a conversion technique for converting a wave into a signal or a signal into a wave. Here, the wave includes a sound wave, an electromagnetic wave and the like. The sound wave has a frequency of about 20 to 20 kHz. The electromagnetic wave includes a light wave, a radio wave, and the like. The light wave is an electromagnetic wave having a wavelength of about 400 to 750 nm (frequency is 750 THz to 400 THz), and the radio wave is an electromagnetic wave having a frequency of about 3 THz or less. Further, the signal here is a signal encoded and encoded for transmitting information, and the medium may be electricity, sound, light, radio wave, or the like.

  Non-patent documents 1, 2, and 3 are known as conventional techniques of conversion technology.

  In Non-Patent Document 1, interference noise is removed using an array in which sensors are installed at high SN zone positions of a parabolic reflector. The noise removal performance depends on the number of parabolic devices constituting the array.

  In Non-Patent Documents 2 and 3, a pseudo diffuse sound field is generated by a reflecting structure, and a microphone array is installed therein to realize diffuse sensing.

“May 07, 2013 Alma Telescope 16 Japanese parabolic antennas have been installed at the summit,” [online], ALMA NAOJ, [Search February 26, 2014], Internet <http: //alma.mtk .nao.ac.jp / j / news / pressrelease / 201305077095.html> K. Niwa, S. Sakauchi, K. Furuya, M. Okamoto, and Y. Haneda, "Diffused sensing for sharp directivity microphone array", ICASSP 2012, 2012, pp. 225-228 K. Niwa, Y. Hioka, K. Furuya, and Y. Haneda, "Telescopic microphone array using reflector for segregating target source from noises in same direction", ICASSP 2012, 2012, pp. 5457-5460

  However, although Non-Patent Document 1 is an array optimized for one direction, information coming from various directions cannot be analyzed simultaneously. When analyzing information coming from other directions, it is necessary to change the direction of the parabolic device.

  In Non-Patent Documents 2 and 3, by installing an array in a diffuse sound field, the correlation between channels can be reduced, and sounds coming from various directions can be analyzed simultaneously with high spatial resolution. However, since the array is installed in the diffuse sound field, the impulse response length becomes long. When the impulse response length is long, the filter length tends to be long, and there arises a problem that the processing delay increases and the anxiety of the filter increases. In addition, the design itself is complicated, and the amount of calculation at the time of filtering increases.

  It is an object of the present invention to provide a conversion device that can simultaneously analyze waves arriving from various directions with high spatial resolution and shorten the impulse response length between the wave source and the observation point.

In order to solve the above-described problem, according to one aspect of the present invention, a conversion device includes a high SN zone forming unit that forms a high SN zone, M is an integer of 2 or more, m = 1, 2,. M, M m-th conversion units arranged in different positions in the vicinity of the high SN zone and capable of converting sound waves into electric signals or electric signals into sound waves, and n being 1, 2,. M, m ≠ n, and based on the electrical signal of a certain m-th conversion unit and the electrical signal of another n-th conversion unit, sound waves emitted from at least a plurality of positions or directions in space are The electric signal converted in the m conversion unit and the electric signal converted in the nth conversion unit, or the electric signal and nth conversion unit before being converted in the mth conversion unit into sound waves emitted in at least a plurality of positions or directions in space A filtering unit that varies the characteristics of the electrical signal before conversion in The SN zone former is (i) a concave shape with a depression, and the shape of the concave edge is not facing inward, or (ii) a sound fullnel lens, and the vicinity of the high SN zone is (i ) When the high SN zone former is a concave shape with a depression, and the shape of the concave edge is not facing inward, the plane H formed by the concave edge and the plane I passing through the concave bottom formed by the high SN zone former The distance between the high SN zone F and the plane I passing through the concave bottom formed by the high SN zone former is FI, and (1) When HI ≧ FI, 2HI in the specified direction from the concave bottom Up to near the high SN zone, (2) When HI <FI, from the concave bottom to 2FI in the predetermined direction is near the high SN zone, and (ii) The high SN zone former is a full-lens lens of sound In this case, the distance from the surface J on which the sound full-nel lens is arranged to the focal point F of the sound full-lens lens is JF, and the inside of the sound full-lens lens is the surface J. In a predetermined direction until 2JF is in the vicinity of high SN zone.
In order to solve the above-described problem, according to another aspect of the present invention, a conversion device includes a high SN zone forming device that forms a high SN zone, M is an integer of 2 or more, m = 1, 2,. , M, M m-th conversion units arranged in different positions in the vicinity of the high SN zone and capable of converting light waves or radio waves into electrical signals or converting electrical signals into light waves or radio waves, and n as 1 , 2,..., M, m ≠ n, and based on the electrical signal of a certain m-th conversion unit and the electrical signal of another n-th conversion unit, emit from at least a plurality of positions or directions in space. The m-th conversion unit converts the received light wave or radio wave into an electric signal converted in the m-th conversion unit and an electric signal converted in the n-th conversion unit, or light waves or radio waves emitted in at least a plurality of positions or directions in space. Previous electrical signal and electrical signal before being converted in the nth converter The high SN zone former is (i) a concave shape with a depression and a concave edge is not directed inward, or (iii) uses a light wave. In the case, it is a lens, or (iv) it is a radio wave lens when using radio waves, and in the vicinity of the high SN zone, (i) the concave shape that the high SN zone former is recessed, and the concave edge is inside If the shape is not suitable for, the distance between the plane H formed by the concave edge and the plane I passing through the concave bottom formed by the high SN zone former is HI, and the high SN zone F and the high SN zone former are formed. When the distance from the plane I passing through the concave bottom is FI, (1) When HI ≥ FI, 2HI in the specified direction from the concave bottom is near the high SN zone, and (2) When HI <FI, From the bottom of the concave shape to 2FI in the specified direction is near the high SN zone, and (iii), (iv) the high SN zone former is a lens or radio lens, The distance from the surface J where the lens is placed to the focal point F of the lens or radio lens is JF, and the high SN zone former is inside the lens or radio lens, and from the plane J to 2 JF in the specified direction is the high SN zone It is near.

  According to the present invention, (1) waves coming from various directions can be analyzed simultaneously, (2) (i) impulse response is short, (ii) transmission / reception energy is high, and (iii) interchannel correlation is low. There is an effect that enables transmission and reception of signals that satisfy the above three conditions.

The figure for demonstrating the conditions of a sound-collecting apparatus. The figure which shows the parabolic antenna, an antenna element, and an example of arrangement | positioning. The figure for demonstrating the area where SN ratio is high when an electromagnetic wave comes from the direction different from a predetermined direction. The figure which shows the function structure of the sound collection device which concerns on 1st embodiment. The figure which shows the example of the processing flow of the sound collection device which concerns on 1st embodiment. The figure which shows the example of arrangement | positioning of the microphone with respect to a high SN zone former. The figure which shows the example of arrangement | positioning of the microphone with respect to a high SN zone former. The figure for demonstrating the range of "near high SN zone." The figure for demonstrating the range of "near high SN zone." The figure for demonstrating the vicinity of a surface similar to a high SN zone formation surface. The figure for demonstrating the method to measure a transfer characteristic. The figure for demonstrating the range of the "near high SN zone" at the time of using a lens. The figure which shows the function structure of the reproducing | regenerating apparatus which concerns on 2nd embodiment. The figure which shows the example of the processing flow of the reproducing | regenerating apparatus which concerns on 2nd embodiment. The figure for demonstrating the positional relationship of the microphone with respect to the high SN zone former in 3rd embodiment. The figure which shows the function structure of the sound collection device which concerns on 3rd embodiment. The figure which shows the example of arrangement | positioning of the microphone with respect to a high SN zone former. The figure which shows the example of arrangement | positioning of the microphone with respect to a high SN zone former.

Hereinafter, embodiments of the present invention will be described. In the drawings used for the following description, constituent parts having the same function and steps for performing the same process are denoted by the same reference numerals, and redundant description is omitted. In the following description, the symbol “ ^→ ” or the like used in the text should be described immediately above the immediately preceding character, but is described immediately after the character due to restrictions on text notation. In the formula, these symbols are written in their original positions. Further, the processing performed for each element of a vector or matrix is applied to all elements of the vector or matrix unless otherwise specified.

<First embodiment>
In this embodiment, an example in which the present invention is applied to a conversion technique for converting a wave into a signal will be described. Examples of conversion techniques for converting waves into signals include the following techniques. There are (1) technology for converting sound waves into electrical signals, and (2) technology for converting electromagnetic waves into electrical signals. However, the present invention is not limited to this, and (3) a technique for converting a sound wave into an optical signal may be used. There is a microphone as a device that realizes (1). There is a receiving antenna as a device that realizes (2). Further, if there is hardware that can directly realize (3), it may be used.

  In particular, in the present embodiment, a case will be described in which sound waves are used as waves and a plurality of microphones (microphone arrays) that convert sound waves into electrical signals are used as a plurality of conversion units.

  First, sound collection processing based on conventional diffusion sensing described in Non-Patent Document 2 will be described.

[Modeling of the observed signal]
Consider a situation where one target sound and K (≧ 1) noises are received using M (≧ 2) microphones. It aims at the directivity control which emphasizes the target sound in arbitrary positions in the presence of many noises. The objective is achieved by suppressing K noise sources and enhancing the target sound. The impulse responses between the m (m = 1,2, ..., M) th microphone and the target sound and the k (k = 1,2, ..., K) th noise are a _m (i) and b _k , respectively. _{, m} (i). However, the impulse response length is L, and i = 0, 1,..., L−1. The impulse response length L may be determined experimentally based on the reverberation time determined by the scale and structure of the apparatus and the situation of the installed room. When the target sound and the k-th noise source signal are s (t) and n _k (t), the observed signal x _m (t) observed by the m-th microphone is modeled by the following equation.

ここで、tは時間のインデックスを表わす。

Here, t represents a time index.

By performing a short-time Fourier transform on x _m (t), the convolutional mixture of Equation (1) is approximated as an instantaneous mixture in the frequency domain as shown in the following equation.

Here, ω and τ represent frequency and frame indexes, respectively. X _m (ω, τ), S (ω, τ) and N _k (ω, τ) are the observed signal x _m (t), the target sound source signal s (t), and the kth noise, respectively. It represents a time-frequency representation of the sound source signal n _k (t). a _m (ω) and b _{k, m} (ω) represent the frequency characteristics between the target sound, the k-th noise and the m-th microphone, and these are hereinafter referred to as transfer characteristics. When Expression (2) is expressed in matrix form, the following expression is obtained.

であり、^Tは転置を表わす。

And ^T represents transposition.

[Beam forming]
The output signal y (t) after beam forming is obtained by convolving an observation signal x _m (t) with a filter w _m (t) designed to emphasize the target sound as in the following equation.

Here, J represents the filter length and may be approximately the same as the impulse response length L. Y (ω, τ), which is a time frequency representation of y (t), is approximately obtained by the following equation.

ここで、^Hは共役転置を表し、W_m(ω)の複素共役がw_m(j)の周波数応答に対応する。

Where ^H represents the conjugate transpose, and the complex conjugate of W _m (ω) corresponds to the frequency response of w _m (j).

When the noise component included in the output signal Y (ω, τ) is written as Y _N (ω, τ), the power p _N (ω) in the following equation is defined as the power of the noise component.

ここで、E_Tは時間的な期待値演算を表わす。音源信号が互いに無相関であると仮定すると、パワーp_N(ω)は伝達特性b^→ _k(ω)とフィルタW^→(ω)だけで計算できる。

Here, E _T represents a temporal expected value calculation. Assuming that the sound source signals are uncorrelated with each other, the power p _N (ω) can be calculated only by the transfer characteristic b ^→ _k (ω) and the filter W ^→ (ω).

In the field of array signal processing, various filter design methods have been described to minimize p _N (ω). As a representative example, the delay sum method and the maximum likelihood method will be described (see Reference 1).
[Reference 1] Taita Asano, “Sound Array Signal Processing-Low Level Tracking and Separation of Sound Sources”, Corona, 2011 In the delay sum method, filter W ^→ _DS Designed to emphasize.

は、ターゲット音の直接音のアレイ・マニフォールド・ベクトルを表わす。要素h_m(ω)は、ターゲット音からm番目のマイクロホンまでの直接音の経路の伝達特性を表し、ターゲット音とm番目のマイクロホン間の距離をd_m、音速をc、虚数単位をjとすると、例えば次式により計算できる。

Represents the array manifold vector of the direct sound of the target sound. The element h _m (ω) represents the transfer characteristic of the direct sound path from the target sound to the m-th microphone, where d _{m is} the distance between the target sound and the m-th microphone, c is the speed of sound, and j is the imaginary unit. Then, for example, it can be calculated by the following equation.

In the maximum likelihood method, the filter W ^→ _ML is designed to enhance the direct sound of the target sound and minimize the power p _N (ω) by the following equation.

Here, R (ω) represents a spatial correlation matrix of noise. For example, assuming that the sound source signals are uncorrelated, the noise spatial correlation matrix R (ω) is calculated using only the transfer characteristic b ^→ _k (ω) as shown in the following equation.

In classical array signal processing as described in Reference 1, it has been considered how to arrange the intervals between microphones. However, the correlation between microphones is often high except for specific frequencies. The following two are known as typical problems. The first is that in a low frequency band with a long wavelength, the correlation between transfer characteristics tends to be high, so that narrow directivity control is difficult. Second, in a high-frequency band with a short wavelength, spatial aliasing that emphasizes sounds other than a specific target sound occurs unless microphones are arranged at intervals of half a wavelength or less. From the above two points, it has been difficult to reduce the power p _N (ω) over a wide band.

[Diffusion sensing]
In Non-Patent Document 2, in order to reduce the power p _N (ω) over a wide band, the nature of the transfer characteristic should be examined and summarized as diffusion sensing.

  In diffuse sensing, by devising the array structure, the transfer characteristics themselves are physically changed so as to be uncorrelated with each other as expressed by the following equation.

Here, any physical means for changing the nature of the transfer characteristic itself can be used. For example, by installing a reflective structure near the microphone, the transfer characteristic itself changes. The method proposed in Non-Patent Document 2 is a method of generating a sound field (pseudo-diffused sound field) in which reflected sound arrives isotropically, repeating a number of reflections, and installing a microphone array therein. . For example, if a reflection structure having a shape surrounding the microphone array is made and only one surface is opened, the sound arriving in the reflection structure is automatically reflected and a pseudo diffuse sound field is generated.

  The reason why the transmission characteristics are uncorrelated when a microphone array is installed in the diffuse sound field will be briefly described. It is known that the correlation γ (ω) in the diffuse sound field is calculated by the following equation, where γ (ω) is the correlation between the transfer characteristics.

Here, E _S , p ^→ represents a spatial expected value calculation and a position vector between microphones, respectively. If the distance || p ^→ || between the microphones is sufficiently wide, the expected value of the correlation γ (ω) between the transfer characteristics in the diffuse sound field gradually approaches zero.

Therefore, in the prior art, a pseudo diffuse sound field is physically generated by a reflective structure, and a microphone array is installed therein (see Non-Patent Documents 2 and 3).

In addition, in order to reduce the power p _N (ω), filter design methods using transfer characteristics prepared by prior simulation and measurement have been studied. Simply put, only the target sound has been emphasized, but the control based on diffuse sensing is designed to emphasize the transfer characteristic itself.

When the delay sum method is used as a base, the filter W ^→ _DS1 (ω) is designed by replacing the array manifold vector h ^→ (ω) with the target sound transfer characteristic a ^→ (ω) as shown in the following equation. it can.

この場合、a^→(ω)をシミュレーションや実測により事前に用意する必要がある。

In this case, a ^→ (ω) needs to be prepared in advance by simulation or actual measurement.

Further, when the maximum likelihood method is used as a base, the filter W ^→ _DS2 (ω) can be designed by the following equation.

In this case as well, it is necessary to prepare a ^→ (ω) and R (ω) in advance by simulation or actual measurement. When a pseudo diffuse sound field is generated using the means described above and the sound is picked up, it is expected that the transfer characteristic is naturally uncorrelated, so the power p _N (ω ) Could be reduced over a wide band.

<Points of first embodiment>
In the zoom-up microphones of Non-Patent Documents 2 and 3, the sound structure is reflected many times by the reflecting structure to generate a sound field (pseudo-diffused sound field) where the reflected sound arrives isotropically, and an array is placed inside the sound field. Because of the installation, the impulse response length becomes longer, the filter length becomes longer accordingly, the occurrence of processing delay and the instability of the filter increase.

  In this embodiment, the idea of reducing the correlation between channels in the zoom-up microphones of Non-Patent Documents 2 and 3 is inherited, and the SN ratio at the time of sound reception is increased while maintaining a short impulse response length. With such a configuration, information coming from various directions can be analyzed stably and simultaneously with high spatial resolution.

  In this embodiment, in order to increase the SN ratio at the time of sound reception, a high SN zone is formed using a high SN zone forming device, and a plurality of microphones are arranged in the vicinity of the high SN zone. At this time, in order to reduce the correlation between channels, each microphone is arranged at a different position (location) near the high SN zone. The high SN zone is a range in which the SN ratio is particularly increased by the high SN zone former. For example, when the high SN zone former is a parabolic reflector, it is a focal point formed by the parabolic reflector. . The vicinity of the high SN zone means a range in which the SN ratio is increased when the high SN zone former is present, as compared with the case where the high SN zone former is not present. Therefore, naturally, the high SN zone is included, but it is not as high as the high SN zone, but includes a range where the SN ratio is increased.

  The conditions of the sound collection device defined in this embodiment will be described with reference to FIG.

[Prerequisite]
(1) Including a high SN zone former that forms a high SN zone
One or more high SN zone formers 190 are included. The high SN zone forming unit 190 forms a high SN zone F with respect to the sound wave. For example, a concave structure made of a rigid body is used as the high SN zone former 190. A parabolic reflector can be considered as one of the concave structures. Note that the minimum required number of high SN zone forming units 190 is one.

(2) Including multiple microphones arranged at different positions on the FE near the high SN zone.
It includes M microphones 211-m. However, M is an integer of 2 or more, and m = 1, 2,. The microphone 211-m is disposed in the vicinity of the high SN zone FE, and the microphone 211-m and the microphone 211-m ′ are disposed at different positions. However, m ′ is any one of 1, 2,..., M, and m ≠ m ′. Note that the minimum number of microphones 211-m is two.

(3) Including a filtering unit
A filtering unit 160 that can perform independent filtering on M microphones. Further, the filtering unit 160 performs signal processing for controlling not only the direct wave but also the transfer characteristic itself including the reflected wave.

<Outline of First Embodiment>
Normally, the parabolic antenna 90 having a parabolic curved reflector is assumed to receive radio waves from one direction (for example, the front direction), and an antenna element 91 is disposed at the focal point F (see FIG. 2). By adopting such a configuration, radio waves can be received not on the point but on the surface, and the SN ratio can be increased.

  When radio waves come from other directions, an area Q having a high SN ratio is generated near the focal point (see FIG. 3). Such a property is not limited to the parabolic antenna, and the same property appears when a concave reflection part is provided to form the focal point of a sound wave. In the present embodiment, using such a property in the vicinity of the high SN zone such as the focal point, a plurality of microphones are arranged in the vicinity of the high SN zone such as the focal point to increase the SN ratio.

  Further, the microphone 211-m and the microphone 211-m ′ are arranged at different positions, thereby reducing the correlation between channels. When a plurality of microphones are arranged at the focal point, although the SN ratio is high, the inter-channel correlation becomes very high, so that radio waves coming from various directions cannot be received, and radio waves coming from one direction are received. It becomes the structure which can receive only with high precision.

Note that increasing the SN ratio means increasing the diagonal component of the spatial correlation matrix R. However, if the observation signal collected by the microphone 211-m is X _m , the mm ′ component of the spatial correlation matrix R is R _{mm ′} = E [X _m X _{m ′} ^H ]. Here, m = 1,2, ..., M, m '= 1,2, ..., M, and when m = m', the diagonal component of the spatial correlation matrix R becomes R _mm = E [X _m X _m ^H] represents the received sound energy of the microphone 211-m (power). E [•] represents an expected value calculation. On the other hand, reducing the inter-channel correlation means that the non-diagonal component of the spatial correlation matrix R is set to a small value. Satisfying these two conditions simultaneously corresponds to maximizing the determinant det (R) of the spatial correlation matrix R. .

  In the present embodiment, a plurality of microphones are arranged at different positions near the high SN zone so as to maximize the determinant det (R). Further, in the present embodiment, in order to shorten the impulse response length, in other words, in order to shorten the filter length used in the filtering unit, the shape of the high SN zone former 190 is changed to the number of times of reflection of sound waves. It forms so that it may become. In terms of time, the shape of the high SN zone former 190 is formed so that the difference in arrival time between the direct sound and the main reflected wave at the microphone is within 50 ms. For example, it is a parabolic shape.

<Sound Pickup Device 10 according to First Embodiment>
[Signal processing of sound collection device 10]
The functional configuration and processing flow of the sound collection device 10 according to the first embodiment are shown in FIGS. 4 and 5. The sound collection device 10 according to the first embodiment includes M microphones 211-m, an AD conversion unit 120, a frequency domain conversion unit 130, a filtering unit 160, a time domain conversion unit 170, a filter calculation unit 150, and a transfer characteristic storage unit. 140, including a high SN zone former 190. m = 1, 2,..., M, and M ≧ 2.

<High SN zone forming device 190>
The high SN zone forming unit 190 forms a high SN zone for waves in a predetermined direction. The high SN zone forming unit 190 has a high SN zone forming surface for forming a high SN zone. The high SN zone forming surface has a shape, material and size capable of reflecting sound waves, and forms a high SN zone by reflecting sound waves. In this embodiment, the high SN zone former 190 is a parabolic rigid body, and the parabolic inner surface corresponds to the high SN zone forming surface. Therefore, the focal point formed by the parabolic shape corresponds to the SN zone, and the vicinity of the focal point corresponds to the vicinity of the SN zone. It is desirable that the diameter of the circle formed by the parabola-shaped edge is not less than about half the maximum wavelength width among the wavelength widths to be handled. Accordingly, since the wavelength width handled by the wavelength of the sound wave is 0.01 to 1 m, it is desirable that the diameter of the circle formed by the parabolic edge is about 0.5 m or more. The material of the high SN zone forming device 190 is preferably a material that easily reflects sound waves (in other words, a material having a high reflection coefficient), and is preferably a hard material. Therefore, in this embodiment, a hard parabolic rigid body having an area is used as the high SN zone forming device 190.

<Microphone 211-m>
Sound is collected using M microphones 211-m (s <b> 1), and an analog signal (sound collection signal) is output to the AD converter 120. The microphone 211-m and the microphone 211-m ′ are arranged at different positions near the high SN zone formed by the high SN zone forming unit 190. Here, m ′ is any one of 1, 2,..., M, and m ≠ m ′.

<Position of microphone 211-m with respect to high SN zone former 190>
M microphones may be arranged so that the determinant det (R) of the spatial correlation matrix R is maximized. In order to increase the SN ratio, M microphones are placed near the high SN zone. In addition, M microphones are arranged at different positions so that the correlation between channels is low. In other words, M microphones may be arranged so that the correlation between sound waves converted into electrical signals by M microphones is low. Although it is desirable to arrange M microphones so that the correlation is low as a whole, it is possible to obtain an effect by arranging M microphones 211-m so that at least one correlation is low. . In other words, in the M microphones, combinations of correlation between the sound waves is converted by any two microphones is considered _{two M} C, among the combinations _M C ₂ of the correlation, M microphones 211-m may be arranged so that at least one correlation is low.

  6 and 7 show examples of arrangement of the microphones 211-m with respect to the high SN zone former 190, respectively.

  In this embodiment, the microphone 211-m is supported by a support portion 191 having a shape that does not easily block waves arriving at the high SN zone former 190.

  In FIG. 6, the support portion 191 is a structure including a surface located in the vicinity of the high SN zone formed by the high SN zone forming device 190, and a hole for holding the microphone 211-m is formed on the surface. A plurality are formed. For example, M ′ (M ′> M) holes are formed, and each microphone 211-m is embedded in one of the M ′ holes. In this embodiment, the support portion 191 includes a mesh member 191A and a support member 191B. The support member 191B is a rod-like structure that forms each side extending from the top of a regular pyramid with the bottom of the parabolic high SN zone former 190 as the top. A net-like net-like member 191A is provided on the same plane as the bottom surface of the regular quadrangular pyramid. The support member 191B couples the high SN zone former 190 and the mesh member 191A, and fixes the mesh member 191A to the high SN zone former 190. The net-like member 191A is a structure including a surface located in the vicinity of the high SN zone formed by the high SN zone forming device 190. Further, a plurality of holes for holding the microphone 211-m are formed in the mesh member 191A. In other words, M microphones 211-m can be embedded in any of the meshes of the mesh-like mesh member 191A.

  In FIG. 7, the support portion 191 is a rod-shaped structure that couples the high SN zone former 190 and the microphone 211-m.

  The shape of the support portion 191 is not limited to the above-described shape, and is any shape as long as it is difficult to block the waves arriving at the high SN zone former 190 and can support the microphone 211-m. Also good.

“Near high SN zone” will be described. As described above, the high SN zone means a high SN zone (for example, a focal point) formed by the high SN zone former 190 with respect to a wave in a predetermined direction. For example, the high SN zone former 190 is concave and concave so as to form a high SN zone. In the direction perpendicular to the predetermined direction, the range “near the high SN zone” means the inside of the concave edge (see FIGS. 8 and 9). Depending on the positional relationship between the concave edge and the high SN zone, the range of “near the high SN zone” in a predetermined direction differs. The distance between the plane H formed by the concave edge and the plane I passing through the bottom of the concave formed by the high SN zone former 190 is HI, and the plane I passing through the concave bottom formed by the high SN zone F and the high SN zone former 190 If the distance between and is FI,
(1) When HI ≧ FI, the range from the concave bottom to 2HI in the predetermined direction is the “near high SN zone” in the predetermined direction (see FIG. 8).

  (2) When HI <FI, the range from the concave bottom to 2FI in the predetermined direction is the “near high SN zone” in the predetermined direction (see FIG. 9).

  However, even if it is a concave concave shape so as to form a high SN zone, the surface formed by the edge is not necessarily flat, and the high SN zone (for example, the focal point) is not a strict point, Since it has a certain range, “near the high SN zone” means a range where the SN ratio is higher in some cases than in the case where there is no high SN zone former 190.

  In the vicinity of the high SN zone, particularly in the vicinity J′E of the surface J ′ similar to the high SN zone forming surface J (S10), the SN ratio becomes high (FIG. 10). By arranging the microphone 211-m, the determinant det (R) of the spatial correlation matrix R can be more appropriately maximized. The vicinity J'E near the surface J 'having a similar shape may be said to be on the surface having a similar shape to the high SN zone forming surface J, or to the vicinity of the surface having a similar shape to the high SN zone forming surface. Also good. In short, in the vicinity of the high SN zone where the SN ratio is high, in particular, M microphones 211-m may be arranged at different positions in a range where the SN ratio is considered to be high.

<AD converter 120>
AD converter 120 converts M analog signals picked up by M microphones 211-m into digital signal x ^→ (t) = [x ₁ (t),..., X _M (t)] ^T (S2) and output to the frequency domain transform unit 130. t represents a discrete time index.

<Frequency domain converter 130>
First, the frequency domain conversion unit 130 receives the digital signal x ^→ (t) = [x ₁ (t),..., X _M (t)] ^T output from the AD conversion unit 120 and outputs N samples for each channel. The digital signal x ^→ (τ) = [x ^→ ₁ (τ),..., X ^→ _M (τ)] ^T is stored in the buffer. τ is an index of the frame number. x ^→ _m (τ) = [x _m ((τ−1) N + 1),..., x _m (τN)] (1 ≦ m ≦ M). N depends on the sampling frequency, but in the case of 48 kHz sampling, around 2048 points is reasonable. Next, the frequency domain transform unit 130 converts the digital signal x ^→ (τ) of each frame into the frequency domain signal X ^→ (ω, τ) = [X ₁ (ω, τ),..., X _M (ω, τ )] Convert to ^T (s3) and output. ω is an index of discrete frequency. One method for converting a time domain signal to a frequency domain signal is a fast discrete Fourier transform, but the present invention is not limited to this, and other methods for converting to a frequency domain signal may be used. The frequency domain signal X ^→ (ω, τ) is output for each frequency ω and frame τ.

<Transfer characteristic storage unit 140>
The transfer characteristic storage unit 140 stores the transfer characteristic A ^→ (ω) = [a ^→ (ω), b ^→ ₁ (ω),..., B ^→ _K (ω)] measured using the sound collecting device 10 in advance. Remember. a ^→ (ω) = [a ₁ (ω), ..., a _M (ω)] ^T is the transfer characteristic at the frequency ω between the target sound and M microphones, in other words, a ^→ (ω ) = [A ₁ (ω),..., A _M (ω)] ^T is a transfer characteristic at the frequency ω of the target sound to each microphone included in the microphone array. k = 1,2, ..., K, where K is the number of noises, b _k ^→ (ω) = [b _k1 (ω), ..., b _kM (ω)] ^T , noise k and M Transfer characteristic at the frequency ω with the other microphones, in other words, b _k ^→ (ω) = [b _k1 (ω),..., B _kM (ω)] ^T to each microphone included in the microphone array The transfer characteristic at the frequency ω of the noise k of Note that the transfer characteristic A ^→ (ω) may be prepared in advance by a theoretical formula or simulation, not by prior measurement.

  For example, as shown in FIG. 11, the speaker array 95 on the rail 94 is moved left and right, and the transfer characteristics at each position are measured. Further, the transfer characteristic at each position may be measured by moving the rail 94 back and forth. In FIG. 11, a plurality of high SN zone formers 190 are used, but only one high SN zone former 190 may be used. The transfer characteristics may be measured in advance in the same situation as the usage situation (the same number, the same arrangement, the same high SN zone former 190, and the same M, the same microphone 211-m). At this time, M microphones 211-m may be arranged for one high SN zone former 190 so that the determinant det (R) of the spatial correlation matrix R is maximized.

<Filter calculation unit 150>
The filter calculation unit 150 extracts the transfer characteristic A ^→ (ω) from the transfer characteristic storage unit 140, calculates the filter W ^→ (ω), and outputs it to the filtering unit 160. For example, a filter W ^→ (ω) used for signal processing for suppressing an acoustic signal from a specific position or direction is calculated.

The main point of the beam forming technology of this embodiment is that a plurality of microphones are arranged near the high SN zone to increase the SN ratio, and a plurality of microphones are arranged at different positions near the high SN zone to transfer characteristics over a wide band. Is to be decorrelated. Therefore, since the filter design concept itself is not affected, the filter W ^→ (ω) can be designed by the same method as in the prior art. For example, the filter design method based on the <1> signal-to-noise ratio maximization criterion described in Reference 2, <2> the filter design method based on Power Inversion, <3> one or more blind spots (noise (4) Filter design method based on the minimum variance distortionless response method with the constraint that the gain is suppressed), <4> Filter design method based on the delay-and-sum beam forming method, and <5> Maximum likelihood method. The filter W ^→ (ω) can be designed by a filter design method, <6> AMNOR (Adaptive Microphone-array for Noise Reduction) method, or the like.
[Reference Document 2] International Publication No. WO2012 / 086834 For example, when the delay sum method is used as a base, the filter W ^→ _DS1 (ω) is calculated by the equation (16).

Further, for example, when the maximum likelihood method is used as a base, the filter W ^→ _DS2 (ω) is calculated by Expression (17).

Further, for example, in the case of a filter design method based on the minimum variance distortionless response method having one or more blind spots as constraints, the filter W ^→ _DS3 (ω) is calculated by the following equation.

Here, f _S (ω) and f _k (ω) represent the pass characteristics at the frequency ω with respect to the target sound and noise k (k = 1, 2,..., K), respectively. For example, in equation (18), if transfer characteristic a ^→ (ω) can be prepared in advance as transfer characteristic a ^→ (ω, θ) depending on direction θ, transfer characteristic a ^→ (ω, θ) is used. Thus, the filter W ^→ (ω, θ) is calculated, and the filtering unit 160 can perform signal processing in a specific direction θ _s . If transfer characteristic a ^→ (ω) can be prepared in advance as transfer characteristic a ^→ (ω, θ, D) depending on direction θ and distance D, transfer characteristic a ^→ (ω, θ, D) The filter W ^→ (ω, θ, D) is calculated, and the filtering unit 160 can perform signal processing at a specific position (a position specified by a specific direction θ _s and a distance D _H ).

<Filtering unit 160>
The filtering unit 160 receives the filter W ^→ (ω) from the filter calculation unit 150 in advance, receives the frequency domain signal X ^→ (ω, τ), and for each frequency ωεΩ for each frame τ, the frequency domain signal X ^→ (ω, τ) = [X ₁ (ω, τ), ..., X _M (ω, τ)] Applying filter W ^→ (ω) to ^T (see equation (5), s4), output The signal Y (ω, τ) is output.

For example, the filtering unit 160 varies the sound collection characteristics of the acoustic signals emitted from at least a plurality of positions or directions in the space based on the sound collection signal from the microphone 211-m and the sound collection signal from the microphone 211-m ′. Anything is acceptable. “Different sound collection characteristics” means, for example, locally collecting an acoustic signal emitted at a specific position so as not to collect an acoustic signal emitted at another position as much as possible, It means that the sound signal emitted at the position is suppressed (silenced) and only the sound signal emitted at another position is collected.

<Time domain conversion unit 170>
The time domain conversion unit 170 converts the output signal Y (ω, τ) of each frequency ω∈Ω of the τ-th frame into the time domain (s5), and converts the frame unit time domain signal y (τ) of the τ-th frame. Then, the obtained frame unit time domain signal y (τ) is connected in the order of the index of the frame number to output the time domain signal y (t). The method of converting the frequency domain signal to the time domain signal is an inverse transform corresponding to the transform method used in the process of s3, for example, a fast discrete inverse Fourier transform.

<Effect>
With such a configuration, the idea of reducing the correlation between channels in the zoom-up microphones of Non-Patent Documents 1 and 2 can be inherited, the impulse response length can be shortened, and the SN ratio during sound reception can be increased. Therefore, it is possible to analyze waves arriving from various directions (and information indicated by the waves) stably and simultaneously with high spatial resolution. For example, by performing appropriate signal processing using a filter using a transfer characteristic prepared in advance, arbitrary directivity control can be performed over a wide band. In the present embodiment, the filter W ^→ (ω) is calculated in advance. However, the filter calculation unit 150 determines the frequency after the sound source position and the microphone arrangement are determined according to the calculation processing capability of the sound collection device 10 and the like. The filter W ^→ (ω) for each may be calculated.

<Modification>
In this embodiment, a sound wave is used as a wave, but a radio wave or a light wave may be used, or an electromagnetic wave in another band may be used. In that case, a receiving antenna, a light receiving element, or the like can be used instead of the microphone. In short, it may be a plurality of conversion units capable of converting the same type of wave into a signal. In other words, the waves converted in the M conversion units may be the same type of waves. Note that the conversion unit may be called a reception unit in the sense that waves can be received. Moreover, you may call a wave source input part in the meaning that the wave transmitted from a wave source (sound source) is input.

  The high SN zone forming device 190 may be realized by a wall, a floor, a ceiling, an iron plate, or a hard sphere (a sphere made of a rigid body (for example, a metal such as iron or a resin). In short, it may be anything as long as it forms a high SN zone for waves in a predetermined direction. However, it is desirable that the number of reflections of sound waves in the vicinity of the high SN zone is about 1 to 2 so that the reverberation time does not become too long. For this reason, the high SN zone forming device 190 does not necessarily have a parabolic shape, but as described above, it is preferably a concave shape having a depression (for example, a bowl shape) and a shape in which reflected sounds are concentrated. Furthermore, it is desirable that the concave edge (end) does not face inward (facing outward) so that the reverberation time does not become too long. For example, when the high SN zone forming device 190 is formed of a part of a sphere, the hemisphere or less is set.

For example, when a radio wave is used as a wave, the high SN zone forming unit 190 may form a high SN zone for a radio wave in a predetermined direction. The wavelength range handled by the wavelength of radio waves is 0.01 to 1 m (see Reference 3).
[Reference 3] “Major uses and characteristics of radio waves by frequency band”, [online], Ministry of Internal Affairs and Communications, [Search February 28, 2014], Internet <http: //www.tele.soumu.go .jp / j / adm / freq / search / myuse / summary />
However, in the case of radio waves, since a specific wavelength is often used, it is desirable that the wavelength is about half or more of the maximum wavelength width among the wavelength widths to be handled according to the specific wavelength. The material of the high SN zone forming device 190 is preferably one that easily reflects radio waves. Therefore, a rigid body having a large area may be used as the high SN zone former 190. Further, for example, the high SN zone forming device 190 may be realized by a reinforcing bar or a building.

In this embodiment, the parabolic rigid body is used as the high SN zone former 190, but the high SN zone former 190 may not be capable of reflecting sound waves. In short, a high SN zone is formed, and even if there is a high SN zone former near the high SN zone, an area with an increased SN ratio can be formed as compared to the case where no high SN zone former is present. That's fine. Therefore, the high SN zone may be formed by a method other than reflection. For example, a sound Fresnel lens (see Reference 4) or the like may be used as the high SN zone former 190.
[Reference 4] "Sound Fresnel Lens", [online], Nagoya City Science Museum, [Search February 28, 2014], Internet <http://www.ncsm.city.nagoya.jp/cgi- bin / visit / exhibition_guide / exhibit.cgi? id = S406 & key =% E3% 81% B5 & keyword =% E3% 83% 95% E3% 83% AC% E3% 83% 8D% E3% 83% AB% E3% 83% AC% E3% 83% B3% E3% 82% BA>
In this case, the focal point of the sound Fresnel lens corresponds to the high SN zone, the vicinity of the focal point corresponds to the vicinity of the high SN zone, and the surface on which the sound Fresnel lens is arranged is the high SN zone for forming the high SN zone. It corresponds to the forming surface. In the case of a sound Fresnel lens, since the wavelength range handled by sound waves is wide, the device scale tends to be large. When electromagnetic waves are used as the waves, lenses corresponding to the wavelengths may be used. For example, a normal lens may be used when a light wave is used as a wave, and a radio lens may be used when a radio wave is used as a wave.

  Note that “in the vicinity of the high SN zone” in the case where the lens is used, the range “in the vicinity of the high SN zone” in the direction perpendicular to the predetermined direction means the inside of the lens. Also, assuming that the distance from the high SN zone forming surface J to the high SN zone F is JF, the range from the high SN zone forming surface J to 2JF in the predetermined direction is the range of “near the high SN zone” in the predetermined direction ( (See FIG. 12).

  However, in this case as well, as in the case of using a concave high SN zone former capable of reflecting a wave, “near the high SN zone” cannot be strictly defined. This means a range where the SN ratio is higher in some cases than in the case where there is no.

  In this embodiment, the directivity of the conversion unit is not mentioned, but by using a mixture of electroacoustic transducers having various directivities, the correlation between the transfer characteristics is reduced, and the correlation is made non-correlated. Also good. For example, the directivity of the conversion unit is not limited, but when a microphone is used as the conversion unit, microphones having various directivities such as omnidirectionality, unidirectionality, bidirectionality, and hypercardioid are mixed and used. If electroacoustic transducers with different directivities are arranged at the same position, the transfer characteristics between the same control points will be different. For example, when an omnidirectional microphone and a unidirectional microphone are arranged at the same position, the transfer characteristics between the control point and the omnidirectional microphone, and the control point and the unidirectional microphone The transfer characteristics between them are different. Therefore, by using this condition, a change in the transfer characteristics due to the difference in directivity is used to further reduce the correlation between the transfer characteristics, thereby achieving non-correlation. In other words, non-correlation is achieved by making the directional characteristic of at least one microphone of the plurality of microphones different from the directional characteristic of one other microphone.

<Second embodiment>
A description will be given centering on differences from the first embodiment.

  In this embodiment, an example in which the present invention is applied to a conversion technique for converting a signal into a wave will be described. Examples of conversion techniques for converting signals into waves include the following techniques. There are (i) a technique for converting electrical signals into sound waves, and (ii) a technique for converting electrical signals into electromagnetic waves. However, the present invention is not limited to this, and (iii) a technique for converting an optical signal into a sound wave may be used. There is a speaker as a device for realizing (i). A device that implements (ii) is a transmission antenna. Further, if there is hardware that can directly realize (iii), it may be used.

  In particular, in the present embodiment, a case will be described in which sound waves are used as waves, and a plurality of speakers (speaker arrays) that convert electric signals into sound waves are used as a plurality of conversion units instead of a microphone array including a plurality of microphones. .

  Note that this embodiment relates to a reproducing apparatus that physically modulates transfer characteristics based on diffusion sensing.

[Signal processing of playback device 30]
Consider performing directional control that is emphasized at control point D using M (≧ 2) speakers.

  FIG. 13 and FIG. 14 show the functional configuration and processing flow of the playback apparatus 30 according to the second embodiment. The reproduction apparatus 30 of the second embodiment includes M speakers 311-m, a frequency domain conversion unit 300, a filtering unit 330, a time domain conversion unit 340, a filter calculation unit 320, a transfer characteristic storage unit 310, and a high SN zone formation. A container 390. m = 1, 2,..., M, and M ≧ 2.

  The signal source 200 outputs a sound source signal s (t). In this embodiment, it is assumed that the sound source signal s (t) from the signal source 200 is a digital signal. However, when an analog signal is used as the sound source signal, an AD conversion unit that performs AD conversion of the analog signal into the digital signal s (t) may be provided.

<Frequency domain conversion unit 300>
First, the frequency domain transform unit 300 receives a digital signal s (t), stores N samples in a buffer, and outputs a digital signal s (τ) in units of frames. Next, the frequency domain transform unit 300 converts the digital signal s (τ) of each frame into a frequency domain signal S (ω, τ) (s31) and outputs it.

<Transfer Characteristic Storage Unit 310 and Filter Calculation Unit 320>
The functional configurations of the transfer characteristic storage unit 310 and the filter calculation unit 320 are the same as in the first embodiment. For example, the filter calculation unit 320 extracts the transfer characteristic A ^→ (ω) from the transfer characteristic storage unit 310, calculates the filter W ^→ (ω) by the method described in Reference 5, and outputs it to the filtering unit 330. For example, a filter W ^→ (ω) used for signal processing for suppressing an acoustic signal in a specific position or direction is calculated.
[Reference 5] Yoichi Haneda, Akitoshi Kataoka, “Real-space performance of small speaker array based on multipoint control using free space transfer function”, Proc. Of the Acoustical Society of Japan, 2008, pp.631-632

<Filtering unit 330>
The filtering unit 330 receives the filter W ^→ (ω) from the filter calculation unit 320 in advance, receives the frequency domain signal S (ω, τ), and for each frequency ωεΩ for each frame τ, the frequency domain signal S ( (ω, τ) is applied with the filter W ^→ (ω) (see the following equation, s32), and the output signal Z ^→ (ω, τ) = [Z ₁ (ω, τ),..., Z _M (ω, τ)] is output.

For example, the filtering unit 330 only needs to change the reproduction characteristics of the acoustic signals emitted from the M speakers 311-m to at least a plurality of positions in the space. “Different playback characteristics” means, for example, that an acoustic signal is locally reproduced at a specific position so that the acoustic signal is not reproduced at other positions as much as possible, and conversely, an acoustic signal is not reproduced at a specific position. This means that the sound signal is reproduced only at other positions.

<Time domain conversion unit 340>
The time domain transform unit 340 uses the reproduction signal Z ^→ (ω, τ) = [Z ₁ (ω, τ),..., Z _M (ω, τ)] of each frequency ω∈Ω of the τ-th frame in the time domain. (S33) to obtain a frame unit time domain signal z ^→ (τ) = [z ₁ (τ),..., Z _M (τ)] of the τ-th frame, and the obtained frame unit time domain The signal z ^→ (τ) = [z ₁ (τ),..., Z _M (τ)] is connected in the order of the frame number index, and the time domain signal z ^→ (t) = [z ₁ (t), …, Z _M (t)] is output. The method of converting the frequency domain signal into the time domain signal is an inverse transform corresponding to the transform method used in the process of s31, for example, a fast discrete inverse Fourier transform.

<Speaker 311-m and high SN zone forming device 390>
The time domain signals z ₁ (t),..., Z _M (t) of the M channel are reproduced by the speakers corresponding to the channel among the M speakers 311 constituting the speaker array (s34).

  The high SN zone former 390 has the same configuration as the high SN zone former 190 of the first embodiment. The positional relationship of the M speakers with respect to the high SN zone former 390 is the same as that of the high SN zone former 190 and M microphones 211-m in the first embodiment. Each may be replaced with 311-m. That is, M speakers may be arranged so that the determinant det (R) of the spatial correlation matrix R is maximized. In order to increase the S / N ratio, M speakers are arranged near the high SN zone (focal point). In addition, M speakers are arranged at different positions so that the correlation between channels is low. In other words, the M speakers may be arranged so that the correlation between sound waves converted into electrical signals by the M speakers is low.

<Effect>
With such a configuration, the correlation between channels can be reduced, the impulse response length and the filter length can be shortened, and sound waves can be reproduced stably and simultaneously in various directions with high spatial resolution. Become. For example, by performing appropriate signal processing using a filter using a transfer characteristic prepared in advance, arbitrary directivity control can be performed over a wide band. In the present embodiment, the filter W ^→ (ω) is calculated in advance. However, the filter calculation unit 350 determines the frequency for each frequency after the reproduction position and the microphone arrangement are determined according to the calculation processing capability of the reproduction device 30 and the like. The filter W ^→ (ω) may be calculated.

<Modification>
As in the first embodiment, sound waves are used as waves, but radio waves and light waves may be used, and electromagnetic waves in other bands may be used. In that case, a transmitting antenna, a light emitting element, or the like can be used instead of the speaker. In short, it may be a plurality of conversion units capable of converting a signal into the same kind of wave. Note that the conversion unit may be called a transmission unit in the sense that a wave can be transmitted. Note that the reception unit and the transmission unit described in the modification of the first embodiment may be collectively referred to as a transmission / reception unit. Further, the conversion unit may be called a wave source output unit in the sense that it becomes a wave source and outputs a wave. In addition, you may call a wave source input / output part together with the wave source input part demonstrated in the modification of 1st embodiment.

  Note that the same modification as in the first embodiment is possible by replacing the microphone with a speaker.

<Third embodiment>
A description will be given centering on differences from the first embodiment.

<Points of third embodiment>
Similar to the first embodiment, the present embodiment also inherits the idea of reducing the correlation between channels in the zoom-up microphones of Non-Patent Documents 2 and 3, and further reduces the SN response at the time of sound reception while shortening the impulse response length. Increase the ratio.

In the first embodiment, M microphones 211-m are provided for one high SN zone former 190. On the other hand, in the present embodiment, N high SN zone formers 190-n are included, and M _n microphones 211- _mn are provided for each high SN zone former 190-n. N is an integer of 2 or more, n = 1, 2,..., N, M _n is an integer of 1 or more corresponding to n (varies according to n), m _n = 1 _,. To do. Then, the ^{_{(Σ n = 1 N M n}} ) number of microphones _{211-m n} high SN zone former 190-n corresponding to at least one of the microphones _{211-m n} to the microphone _{211-m n} of the form The determinant det (R) is maximized by arranging it at a position other than the high SN zone.

In the present embodiment, in order to increase the SN ratio at the time of sound reception, a high SN zone is formed using N high SN zone formers, and a plurality of microphones are arranged in the vicinity of each high SN zone. At this time, in order to reduce the inter-channel correlation, the position other than the high SN zone n-th high SN zone former 190-n corresponding to at least one of the microphones 211-m _n to the microphone 211-m _n form To place.

[Prerequisite]
(1) Including N high SN zone formers, each forming a high SN zone
N high SN zone formers 190-n are included. Each high SN zone former 190-n has the same configuration as the high SN zone former 190 of the first embodiment.

(2) It includes M _n microphones arranged in the FE near the high SN zone formed by each high SN zone former 190-n. ^{_{Furthermore, (Σ n = 1 N M}} n) number of microphones _{211-m n} high SN zone former 190-n corresponding to at least one of the microphones _{211-m n} to the microphone _{211-m n} of the formation Place it in a location other than the high SN zone. In addition, since at least one microphone 211- _mn is arranged for each high SN zone former 190-n, the necessary minimum number of microphones 211- _mn is N.

(3) Including a filtering unit
A filtering unit 160 that can perform independent filter processing on (Σ _{n = 1} ^N M _n ) microphones. The processing content is the same as that of the filtering unit 160 of the first embodiment, except that the number of input signals is different.
<Outline of third embodiment>
In the present embodiment, utilizing the property in the vicinity of the high SN zone described in the first embodiment, M _n microphones are arranged in the FE near the high SN zone formed by each high SN zone forming unit 190-n, and SN Increase the ratio.

^{_{Further, (Σ n = 1 N M}} n) number of microphones _{211-m n} high SN zone former 190-n corresponding to at least one of the microphones _{211-m n} to the microphone _{211-m n} of the formation By arranging in a position other than the high SN zone, the correlation between channels is reduced.

In particular, by the positional relationship between the microphones _{211-m n_A} to high SN zone former _{190-n A,} the positional relationship between the microphones _{211-m N_B} to high SN zone former _{190-n B} are different manner, placing Therefore, the correlation between channels can be further reduced. However, even in all the positional relationship of the microphones 211-m _n is the same for the N high SN zone former 190-n, the microphone 211-m _n to the position other than the high SN zone F shown in FIG. 15 It only has to be arranged. The high SN zone forming device 190-n having a parabolic shape or the like has a shape such that sound waves are collected in the high SN zone. Therefore, if the microphone 211- _mn is arranged at a position other than the high SN zone, it is not patented. compared with the case of placing all of the microphones as Document 1 to a high SN zone, the correlation between the sound waves picked up by sound waves and a microphone 211-m _{N_B} be collected by the microphone 211-m _{n_A} is lowered, Even with such a configuration, the determinant det (R) can be maximized.

<Sound Pickup Device 50 according to Third Embodiment>
[Signal processing of sound collection device 50]
FIG. 16 shows a functional configuration of the sound collection device 50 according to the third embodiment. The processing flow is the same as that of the sound collection device 10 according to the first embodiment. The sound collection device 50 according to the third embodiment includes an AD conversion unit 120, a frequency domain conversion unit 130, a filtering unit 160, a time domain conversion unit 170, a filter calculation unit 150, a transfer characteristic storage unit 140, and N high SN zones. The former 190-n includes (Σ _{n = 1} ^N M _n ) microphones 211- _mn .

  The configurations of the AD conversion unit 120, the frequency domain conversion unit 130, the filtering unit 160, the time domain conversion unit 170, the filter calculation unit 150, and the transfer characteristic storage unit 140 are the same as those in the first embodiment.

However, rather than the M microphones _{211-m, (Σ n =} 1 N M n) number of picked up by the microphone 211-m _n, in picked up ^{_{(Σ n = 1 N M n}} ) pieces of analog Each processing is performed using a signal or a value corresponding to the analog signal.

<High SN zone former 190-n and microphone 211- _mn >
The N high SN zone formers 190-n have the same configuration as the high SN zone former 190 of the first embodiment.

The (Σ _{n = 1} ^N M _n ) microphones 211- _mn have the same configuration as the microphone 211-m of the first embodiment.

M _n microphones 211- _mn are provided for one high SN zone former 190-n.

<Microphone position _{211-m n} to high SN zone former 190-n>
(Σ _{n = 1} ^N M _n ) microphones 211- _mn may be arranged so that the determinant det (R) of the spatial correlation matrix R is maximized. As described ^{_{above, (Σ n = 1 N M}} n) number of microphones _211-m of _n of at least one microphone _{211-m n} a high SN zone former corresponding to the microphone _{211-m n} 190- By arranging in a position other than the high SN zone (for example, the focal point) formed by n, the correlation between channels is reduced and the determinant det (R) is maximized. In particular, the microphone 211- _{mn_A} relative to the high SN zone former 190-n _A and the microphone 211- _{mn = B} relative to the high SN zone former 190-n _B are arranged differently. Thus, the correlation between channels can be further reduced. However, subscript n_A and n_B represent respectively _{n A} and _{n B,} the _{n A} and _{n B} respectively 1,2, ..., the specific values in the N, and _{n A} ≠ _{n B.}

In other words, a plurality of microphones may be arranged so that the correlation between sound waves converted into electric signals by the plurality of microphones is low. Although it is desirable to arrange a plurality of microphones so that the correlation is low as a whole, at least (Σ _{n = 1} ^N M _n ) microphones 211- _mn are arranged so that one correlation is low. If it does, an effect can be acquired. In other ^{_{words, (Σ n = 1 N M}} n) pieces of in the microphone, the combination of the correlation between the sound waves is converted by any two microphones is considered _{two P} C (provided that P = ^{_{Σ n = 1 n M n)}} , among the combinations _P C ₂ pieces of the correlation, may be arranged such that at least one correlation is low ^{_{(Σ n = 1 n M n}} ) number of microphones 211-m _n .

17 and 18 show an example of the arrangement of the microphones _{211-m n} respectively for a high SN zone former 190-n.

In this embodiment, the microphone 211- _mn is supported by a support portion 191-n having a shape that does not easily block waves arriving at the high SN zone former 190-n. The support part 191-n has the same configuration as the support part 191 of the first embodiment.

In Figure 17, the support portion 191-n is a structure comprising a surface located in the vicinity of the high SN zone high SN zone former 190-n are formed, on the surface to hold the microphone 211-m _n Thus, a plurality of holes are formed.

In Figure 18, the support portion 191-n is the structure of the rod-like coupling the high SN zone former 190-n and the microphone _{211-m n.} FIG. 18 shows an example when N = 3, M ₁ = 3, M ₂ = 3, and M ₃ = 1.

In either embodiment, high SN zone former corresponding to ^{_{(Σ n = 1 N M n}} ) number of microphones _211-m the microphone _{211-m n} at least one microphone _{211-m n} of the _n 190 It is arranged at a position other than the high SN zone (for example, the focal point) formed by -n. Further, the positional relationship between the microphones _{211-m n_A,} the positional relationship between the microphones _{211-m N_B} to high SN zone former _{190-n B} are arranged differently to high SN zone former _{190-n A.} With such a configuration, the positional relationship is different, the correlation between the sound waves picked up by sound waves and a microphone _{211-m N_B} be collected by the microphone _{211-m n_A} decreases. As described above, since the microphone 211- _mn is arranged in the vicinity of the high SN zone of the corresponding high SN zone former 190-n, the SN ratio becomes high. Therefore, such a configuration maximizes the determinant det (R).

<Effect>
With such a configuration, the same effect as that of the first embodiment can be obtained. Incidentally, the point of the present ^{_{embodiment, (Σ n = 1 N M}} n) number of microphones _{211-m n} at least one microphone _{211-m n} of the n-th height corresponding to the microphone _{211-m n} In other _words , the position of the microphone 211- _{mn_A} relative to the high SN zone former 190-n _A and the high SN zone _{former 190-} n so that the positional relationship between the microphones _{211-m N_B} differ for _B, and the microphone _{211-m n_A} microphone _{211-m N_B} is located, if including this point, the first embodiment and the You may combine with two embodiment. For example, FIG. 17 and FIG. 18 are combinations with the first embodiment. For example, in FIG. 18, at different positions in the vicinity of the high SN zone formed by the high SN zone formers 190-1 and 190-2, respectively. each microphone 211-1 ₁ ～211-3 ₁ are disposed a microphone 211-1 ₂ ～211-3 _2. Further, the microphone 211-1 ₁ ～211-3 _1, microphone 211-1 ₂ ～211-3 _2, microphone 211-1 _3, the corresponding high SN zone formatter 190-1 and 190-2 and 190-3 It is arranged at a position other than the high SN zone formed. Further, the positional relationship between the microphones 211-1 ₁ ～211-3 ₁ to high SN zone former 190-1, the positional relationship between the microphones 211-1 ₂ ～211-3 ₂ for high SN zone former 190-2, the positional relationship between the microphone 211-1 ₃ are arranged differently to high SN zone former 190-3. Moreover, the same modification as 1st embodiment and 2nd embodiment is applicable.

<Other variations>
The present invention is not limited to the above-described embodiments and modifications. For example, the various processes described above are not only executed in time series according to the description, but may also be executed in parallel or individually as required by the processing capability of the apparatus that executes the processes. In addition, it can change suitably in the range which does not deviate from the meaning of this invention.

<Program and recording medium>
In addition, various processing functions in each device described in the above embodiments and modifications may be realized by a computer. In that case, the processing contents of the functions that each device should have are described by a program. Then, by executing this program on a computer, various processing functions in each of the above devices are 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.

  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 storage device of the server computer and transferring the program from the server computer to another computer via a network.

  A computer that executes such a program first stores, for example, a program recorded on a portable recording medium or a program transferred from a server computer in its storage unit. When executing the process, this computer reads the program stored in its own storage unit and executes the process according to the read program. As another embodiment of this program, a computer may read a program directly from a portable recording medium and execute processing according to the program. Further, each time a program is transferred from the server computer to the computer, processing according to the received program may be executed sequentially. Also, the program is not transferred from the server computer to the computer, and the above-described processing is executed by a so-called ASP (Application Service Provider) type service that realizes the processing function only by the execution instruction and result acquisition. It is good. Note that the program includes information provided for processing by the electronic computer and equivalent to the program (data that is not a direct command to the computer but has a property that defines the processing of the computer).

  In addition, although each device is configured by executing a predetermined program on a computer, at least a part of these processing contents may be realized by hardware.

Claims (11)

A high SN zone forming device for forming a high SN zone;
M an integer of 2 or more, m = 1, 2, ..., and M, in the vicinity of the high SN zone, disposed at different positions, the sound waves into electrical signals, or capable of converting electrical signals into sound waves M M-th conversion units;
n is any one of 1, 2,..., M, m ≠ n, and at least a plurality of positions in space based on the electrical signal of a certain m-th conversion unit and the electrical signal of another n-th conversion unit or Before the sound wave emitted from the direction is converted by the m-th conversion unit into an electric signal converted by the m-th conversion unit and an electric signal converted by the n-th conversion unit, or a sound wave emitted from at least a plurality of positions or directions in space. And a filtering unit that makes the characteristics of the electrical signal different from that of the electrical signal before being converted in the nth conversion unit ,
The high SN zone former is (i) a concave shape with a depression and a shape where the edge of the concave shape does not face inward, or (ii) a full-lens of sound.
In the vicinity of the high SN zone, (i) when the high SN zone forming device has a concave shape with a depression, and the concave edge is in a shape not facing inward, the plane H formed by the concave edge and the high SN zone forming device HI is the distance from the plane I passing through the concave bottom formed by HI, and FI is the distance between the high SN zone F and the plane I passing through the concave bottom formed by the high SN zone former. (1) When HI ≧ FI From the concave bottom to 2HI in the predetermined direction is near the high SN zone. (2) When HI <FI, the concave bottom to 2FI in the predetermined direction is near the high SN zone. ) When the high SN zone former is a sound fullnel lens, the distance from the surface J where the sound fullnel lens is placed to the focal point F of the sound fullnel lens is JF, and inside the sound fullnel lens From the surface J to 2JF in a predetermined direction is near the high SN zone,
Conversion device. A high SN zone forming device for forming a high SN zone;
M is an integer of 2 or more, m = 1, 2,..., M, and light waves or radio waves arranged at different positions near the high SN zone are converted into electrical signals, or electrical signals are converted into light waves or radio waves . M number of m conversion units that can be converted;
n is any one of 1, 2,..., M, m ≠ n, and at least a plurality of positions in space based on the electrical signal of a certain m-th conversion unit and the electrical signal of another n-th conversion unit or An m-th conversion unit into an electric signal obtained by converting a light wave or radio wave emitted from a direction in the m-th conversion unit and an electric signal converted in the n-th conversion unit, or a light wave or radio wave emitted in at least a plurality of positions or directions in space A filtering unit for differentiating the characteristics of the electric signal before conversion in the electric signal before conversion in the n-th conversion unit,
The high SN zone former is (i) a concave shape with a depression and a shape where the edge of the concave shape does not face inward, or (iii) a lens when using light waves, or (iv) radio waves If you use a radio lens,
In the vicinity of the high SN zone, (i) when the high SN zone forming device has a concave shape with a depression, and the concave edge is in a shape not facing inward, the plane H formed by the concave edge and the high SN zone forming device HI is the distance from the plane I passing through the concave bottom formed by HI, and FI is the distance between the high SN zone F and the plane I passing through the concave bottom formed by the high SN zone former. (1) When HI ≧ FI From the concave bottom to 2HI in the predetermined direction is near the high SN zone. (2) When HI <FI, the concave bottom to the predetermined direction 2FI is near the high SN zone. ), (iv) When the high SN zone former is a lens or radio lens, the distance from the surface J where the radio lens is placed to the focal point F of the lens or radio lens is JF. Inside the lens, from the surface J to 2JF in a predetermined direction is near the high SN zone,
Conversion device. A conversion device according to claim 1 or claim 2 , wherein
The M number of m conversion units are arranged so that the waves converted in the M number of m conversion units or the correlation between the converted waves are low.
Conversion device. The conversion device according to any one of claims 1 to 3 ,
The high SN zone forming device has a high SN zone forming surface for forming the high SN zone.
Conversion device. The conversion device according to claim 4 ,
The high SN zone forming surface is
Converted by the M number of m-th converters, or the reflected waves can be reflected;
Conversion device. A conversion device according to claim 4 or claim 5 , wherein
The M m-th conversion units are:
Arranged in the vicinity of a surface having a similar shape to the high SN zone forming surface,
Conversion device. The conversion device according to any one of claims 1 to 6 ,
The M m-th conversion units are:
It is supported by a support portion having a shape that does not easily block waves arriving at the high SN zone former.
Conversion device. The conversion device according to claim 7 , comprising:
M ′ is an integer greater than or equal to M, and the support is
A structure including a surface located in the vicinity of the high SN zone formed by the high SN zone forming device, wherein M ′ holes for holding the M number of m-th conversion parts are provided on the surface. It is formed,
Conversion device. The conversion device according to claim 7 , comprising:
The support part is
A rod-shaped structure that couples the high SN zone former and the M m-th converters;
Conversion device. The conversion device according to any one of claims 1 to 9 ,
The high SN zone former is a parabolic shape,
Conversion device. Be any converter according to claim 1 0 of claims 1,
The directivity characteristic of at least one m′-th conversion means among the M number of m-th conversion units is different from the directivity characteristic of the other m-th “conversion means”.
Conversion device.

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