JPS6351800A - Sound collection equipment and sound field reproducing method - Google Patents

Abstract

PURPOSE:To attain the collection of sound field rich in the presence by using a 1st, 2nd synthesis means provided at each output of sound collection elements arranged on a semi-circle, a band pass filter means and a 3rd synthesis means so as to extract sound signals in plural directions simultaneously. CONSTITUTION:A microphone Mc is located at the center C of a circle, and microphones 1-7, 101-106 are arranged at an equal interval on a 1st and 2nd semi-circles with radius r1, r2 respectively from the center C, and microphones 8-12, 107-112 are arranged at positions at a symmetrical angle with respect to the center C on the other semi-circles than the 1st and 2nd semi-circles. Moreover, microphones 201-212, 301-312 are arranged on a 3rd and 4th circles with radius r3, r4 respectively from the center C. For example, an audible frequency band is split into four bands, the circles arranged with the microphones are changed depending on each frequency band such as the 1st and 2nd circles for frequencies 700Hz or below, the 2nd and 3rd circles for frequencies 700Hz-1.H, the 3rd and 4th circles for 1.4-2.8kHz and the 4th circle for 2.8kfHz or over to synthesize the outputs of the required microphones. Thus, the sound field abundant in the presence is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application Lijf 1 The present invention relates to a sound collection device and a sound field reproduction method that simultaneously collect sound waves in the audible range in multiple channels according to their direction of arrival.

[Prior art] In the past, there have been examples of using array microbons arranged in a straight line for acoustic measurement, but in order to accurately collect sound arriving from all directions, broadband technology has been developed based on the concept of multi-beams. There is no example of a device capable of collecting acoustic waves.

[Problems to be solved by the invention] When reproducing the sound field of a large space in a small space, conventionally it is difficult to use directional microphones that are placed near each sound source, or to use microphones that collect the atmosphere of the sound field. The output was mixed, and the final sound was collected and played back in two channels.

This is a sound collection and reproduction method that mainly focuses on sound image localization using direct sound, but in an actual large-space sound field, sound waves are incident from all directions, so it is necessary to faithfully reproduce a small space. Therefore, a method must be taken to collect sound correctly in accordance with the direction of incidence.

The object of the present invention is to provide a sound collection device that enables the collection of a sound field full of a sense of presence by correctly collecting acoustic waves arriving from multiple directions at the same time, and a sound field that enables the reproduction of the sound field. The purpose is to provide a method of reproduction.

[Means for Solving the Problems] In order to achieve such an object, in the sound collecting device of the present invention, the sound collecting elements are arranged on a concentric circle or circumscribed on the circumference,
Placed on the periphery of a square that coincides with the diagonal, at a position where it intersects with at least two straight lines that pass through the center of the circle and divide the area around the center at equal angles, and at the center position, and divided by one of the straight lines. The first synthesis is to synthesize the outputs of the sound pickup elements arranged on the semicircle or the periphery of the half-square, by matching the phase of the incident sound in the linear direction for each semicircle or the periphery of the half-square. The frequency band of the incident sound is divided into low, middle, and high bands, and the desired synthesized signal obtained by the first synthesizing means and the seven synthesizers are placed at the center position, corresponding to the desired band. A second synthesizing means for synthesizing the output of the sound pickup element, a filtering means for band-filtering the composite No. 43 for each band obtained by the second synthesizing means, and a filtering means for each band. a third synthesizing means for synthesizing the outputs of the first synthesis means for each of the outputs of the sound pickup elements arranged on each semicircle or semicircular periphery divided by each of the straight lines. The present invention is characterized in that it comprises a means for combining, a second combining means, a bandpass filtering means, and a third combining means, and nine sound signals in a plurality of directions are extracted simultaneously.

In the sound field reproduction method of the present invention (well, by arranging a plurality of sound pickup elements,
By combining the outputs, the original sound field can be reproduced from the acoustic signals from multiple directions that have been collected so as to have composite directional characteristics in multiple directions, and the main beam direction of the custom-made composite directional pattern can be used. The present invention is characterized in that an electroacoustic transducer is disposed at a position where the electroacoustic transducer is located, and acoustic signals in multiple directions are simultaneously amplified by the electroacoustic transducer to reproduce the original sound field. According to the sound collection device, in a sound field in a large space, it is possible to simultaneously and correctly collect acoustic waves incident from all directions according to the direction of incidence.

Further, according to the sound field reproduction method of the present invention, it is possible to reproduce a sound field in a large space of acoustic waves incident from all directions by arranging speakers for each direction of incidence.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is an arrangement diagram of a multi-beam array microphone (MA!J) according to an embodiment of the present invention. In this embodiment, the microphones are arranged in a circumferential manner, and the idea of the present invention can be applied when the number N of microphones on the circumference is 4 or more, but the subsequent analysis will be performed with N set to 12.

In FIG. 1, MC is a microphone placed at center C, 1 to 7 are seven microphones arranged at equal intervals on the first semicircle with radius r1 from center C, and 101 to
Reference numeral 106 denotes six microphones arranged at equal intervals on a semicircle of ¥FJ2 with a radius r2 from the center C.

Five microbons 8 to 12 and six microbons 107 to 108 are also arranged on the first and second other semicircles at symmetrical angle positions with respect to the center C. Shujo and
A total of 12 microphones are arranged on each of the second circumferences.

An arrangement similar to the above arrangement, with a radius r from the center C.
, and 20 on the third and fourth circumferences of r4, respectively.
Twelve microphones 1-212 and 301-312 are arranged at the positions shown in the figure.

Here, in this embodiment, for example, the audible frequency band is
-+J' region, and the frequency band 700 It z or less is divided into the first and second circle 2 frequency bands 70011z -1
, -IKHz for the second and third circles 2 frequency bands 1.4
~2.8KHz 3rd and 4th circle 9 frequency band 28
In each opening a, l(z and above are called the fourth circle)
*Change the circle where the microphones are placed depending on the area, so that the output of each microphone is synthesized.

FIG. 2 is an explanatory diagram of directional synthesis of a multi-beam array microphone according to an embodiment of the present invention.

As shown in FIG. 1, microphones 1 to 7 are arranged at equal intervals on a semicircle of radius r with C as the center in a horizontal plane, and 101 microphones are arranged at equal intervals on a semicircle of radius r2. ~
+08 microphones are arranged respectively. A microphone M is arranged at the center C.

The case where a plane wave is incident from the direction of elevation angle θ and azimuth angle φ will be analyzed below.

In this example, for two concentric circles, the outer radius is
1. If the inner radius is r2 and the wavelength at the frequency of the incident sound of interest is λ, then each microphone's output is delayed so that the phases are aligned in the direction of the straight line connecting 1-C-7. The phase of: is expressed by the following equation.

Phase of microphones 1 and 7 Phase of microphones 2 and 6: Phase of microphones 3 and 5 Phase of microphone 4, α1・sinθ・COSφ Phase of microphones O1 and 106.

(Decoded in the same order) Phase between microphones 102 and 105.

When the phases of microphones 103 and 104 are combined with the output of microphone Mc placed at the center C, the amplitude of the final array output F(θ, φ) is expressed as follows.

8F(θ, φ) = 1Σ exp (jα, sin θ(cos(φ−φ,
)-co, sφi))+11 Using this formula, rl=λ/4~2λ, r2=r,/2
The directivity characteristics in the direction of φ=0° determined for the angle φ=0° are shown in FIGS. 3(A) to 3(D).

That is, the microphones 1 to 7, the microphones 101 to 106, and the microphone M are set in the same phase by a line 1-C-7 that is perpendicular to the direction from the microphone 4.
Let it be synthesized. The directional characteristics of the microphone 4 obtained in this way are shown in FIGS. 3+A) to 3(D).

It can be seen from these FIGS. 3(A) to 3(D) that when r≦λ, the half-width θ=30°, and a guideline for dividing the audible frequency band can be obtained.

From the viewpoint of physically realizing this embodiment as a microphone device, the radius of the maximum circle is 68c+n, which is a half wavelength of 500Hz, and is 34cm, 17cc+, 8.
The basic configuration is to gradually reduce the radius by increasing the radius to 172 cm.

As a result, it is possible to realize a wideband multi-beam array microphone device with little variation in directivity pattern depending on frequency.

FIG. 4 is a block diagram showing the composition circuit configuration in one embodiment of the present invention.

In the figure, 1-7, 101-106, 201-20
7, 301 to 306 and Mc are microphones, respectively. Second. Third. It is placed on the fourth circumference and at the center point. To 1. 82. 8 and 8 are adders, respectively, microphones 1 to 7 placed on the first circumference, and microphones 101 to 108 placed on the second circumference.
microphones 201-2 arranged on the third circumference
07 microphone and 3 placed on the fourth circumference
The outputs of the microphones 01 to 306 are added in phase with each other using tapped delay lines.

Z' is the output of microphone MC placed at the center point.

AL is an adder that adds the outputs of adders A, A2, and 2'. Similarly, AM+, AM2, A)I are adders, and the outputs of adders A2 and A3 and Z', A
3, the output of A4, Z', the output of A, and Z' are added.

21 and 27 are low pass filters (LPF), 22
23 is a band pass filter (BPF), and 24 is a high pass filter (HPF).

25 is an adder, 26 is a D converter (DAC), I
C) I~12CH are channels (CI
It is.

In FIG. 4, it is divided into four bands: a low frequency band, an intermediate frequency band M1 and M2, and a high frequency band H.

For the -11F range, an addition ROM that adds the outputs of seven microphones 1 to 7, and
The output of A2, which is the sum of the six outputs of 106, and the center point C
The outputs of a total of 14 microphones including the output Z' of the microphone Mc are added by an adder AL, and an output is obtained through the LPF 21.

Similarly, for band disease, the outputs of the switchers A2 and A3 and Z', a total of 14 microphones, are added by an adder AM, and an output is obtained through the BPF 22.

For band M2, the outputs of adders A3 and A4 and Z
' Add the outputs of a total of 14 microphones AM2
and output through BPF23.

For band H, adder AH adds the outputs of a total of seven microphones, the output of adder A4 and Z', and
Get the output through F24.

The outputs of M, M2, and H for each band are added by an adder 25, the added output is converted into an analog signal by a DAC 26, and the entire audible frequency band (below 15 KHz) is filtered by an LPF 27. A channel (ICH in the figure) with directional characteristics is created.

In this embodiment, 12 microphones are arranged at equal intervals on one circumference, and the above-mentioned synthesis circuit is configured to have directivity characteristics in 12 directions, so that 12 channels (I CH-12CI+1 can be made.

FIG. 5 is an arrangement diagram of a multi-beam array microphone according to another embodiment of the present invention.

In this example, the microphones are arranged in a rectangular arrangement, and in contrast to the circular arrangement in FIG. 1, the numbers of the microphones arranged in the same direction are represented by the same number with a dash and a 2.

Similarly, a microphone Mc' is placed at the center C'.

The first periphery has a side length it = 1. :16m
This corresponds to the wavelength (λ) of 50014 z, and the second
The periphery of is El/2, the third periphery is u/4, and the fourth periphery is u/8, so that the length of each side is reduced by 1/2.

The composition circuit can be configured in the same manner as the circular array embodiment described above.

For example, the configuration is such that the microphones arranged on the half plane divided by the straight line 1'-c'-7' are synthesized in the same position as the microphone Mc' at the center C'.

FIG. 6 is an explanatory diagram of an example of a circular arrangement for sound collection and reproduction according to the present invention.

The sound is collected using a directional main beam in the direction shown by the arrow, and the reproduction is performed using the same number of electric sound transducers as the number of channels (
(Speakers) are arranged in a circle to amplify the sound in the direction of the arrow.

For example, the collected sound signals can be recorded in multiple channels and then reproduced in multiple channels.

FIG. 7 is an explanatory diagram of an example of a rectangular arrangement regarding sound collection and reproduction according to the present invention.

This is the same as the case of the circular arrangement shown in FIG. 6, and a particular explanation will be omitted.

FIG. 8 is an explanatory diagram of an example of the number of channels related to sound collection and reproduction according to the present invention.

In the figure, ICH- and -12CH are channel numbers for collecting sound in each direction, and A to D are speakers.

In the above embodiment, the maximum number of channels is 12, but it is also possible to accommodate a smaller number of channels by mixing some channels and reducing the number.

In other words, the signal corresponding to the direction of ICH-12cH is
Record on a tape recorder with 21-rack or more, and combine three outputs, for example, 12CH, IC11, and 2CI, from speaker A, and three outputs, 3C]1, 4CH, and 5CH, from speaker B. By doing so, it is possible to realize a reproduction sound field by reducing the number of channels to four.

Furthermore, with the above-described sound collection and reproduction arrangement according to this embodiment, it is possible to use large speakers to reproduce a large spatial sound field in an ILJ field, a jaw room, or the like.

[Effects of the Invention] As is clear from the above, it is known that the lower the frequency, the duller the directivity of the ear is with the sound collecting device of the present invention. It is possible to collect sound with sufficient angular resolution for incident sound from any direction.

Since each of the microphones arranged in the second arrangement may be non-directional, it can be realized in a smaller size and lighter weight.

In addition, according to the sound field reproduction method of the present invention, by using large speakers, it is possible to reproduce a large space sound field in a theater, a Joe room, etc., and even in a small space, it is possible to reproduce the sense of presence in a large space sound field. It is possible to reproduce a warm sound field.

[Brief explanation of drawings]

FIG. 1 is an arrangement diagram of a multi-beam array microphone (M to M) according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of directional synthesis of static M according to an embodiment of the present invention, and FIG. 3 (A) to (D) are composite directional characteristic diagrams of a microphone according to an embodiment of the present invention, FIG. 4 is a block diagram showing a composition circuit configuration according to an embodiment of the present invention, and FIG. An arrangement diagram of ~JAM in an actual S'fs example. Fig. 6 is an explanatory diagram of an example of a circular arrangement for sound collection and reproduction according to the present invention. Fig. 7 is an example of a rectangular arrangement for sound collection and reproduction according to the present invention. Section 8 is an explanatory diagram of an example of the number of channels related to sound collection and reproduction according to the present invention. 1~12,101~102,201~212,301~
312゜Mc...Microphone, r1-r4...Radius, φ...Azimuth, θ...Elevation angle, λ...500) Wavelength of sound at 1z, A1-A 4. AL, AM, AMz, A) 1.25...
- Adder, Z'...Output of microphone MC, 21.27...Low pass filter (LPF), 22.2
3...Band pass filter (BPF), 24...High pass filter (HPF), 26...D/A converter (DAC
), ICHN12c)! ...Channel number representing each direction,

Claims (1)

[Scope of Claims] 1) The sound pickup element is placed on a concentric circle or around a square circumscribed to the circumference and whose diagonals coincide, passing through the center of the circle and equiangularly around the center. split into at least 2
The output of the sound pickup element is placed at a position intersecting with a straight line of the book and at the center position of the book, and is placed on a semicircle or a semicircular periphery divided by one of the straight lines. a first synthesizing means that synthesizes the incident sound by matching the phase of the incident sound in the linear direction for each circumference or for each semicircular periphery, and dividing the frequency band of the incident sound into low, middle, and high bands, and dividing the frequency band of the incident sound into a desired band. a second synthesizing means for synthesizing the required synthesized signal obtained by the first synthesizing means and the output of the sound pickup element disposed at the central position in accordance with the second synthesizing means; filtering means for band-filtering the composite signals for each band obtained by the filtering means, and a third combining means for combining the outputs from the filtering means for each band, The first synthesizing means, the second synthesizing means, the bandpass filtering means, and the third What is claimed is: 1. A sound collection device comprising a synthesis means and capable of simultaneously extracting acoustic signals in a plurality of directions. 2) By arranging multiple sound pickup elements and synthesizing their outputs, it is possible to reproduce the original sound field from acoustic signals from multiple directions collected so as to have composite directional characteristics in multiple directions. , an electroacoustic transducer is placed at a position corresponding to the main beam direction of the composite directional characteristic, and the acoustic signals in the plurality of directions are simultaneously amplified by the electroacoustic transducer to reproduce the original sound field. A sound field reproduction method characterized by: