JPH04157384A - Directional sound detector - Google Patents

Abstract

PURPOSE:To avoid that a sound receiver arrangement becomes large in scale and to prevent deterioration of a low-frequency characteristic by extracting only differences of a measured phase difference from a reference phase difference between arranged sound receivers which are within an allowable range, and by subjecting them to addition and synthesis with a phase difference between the sound receivers made to be zero. CONSTITUTION:Output signals of sound receivers 11 and 12 which are amplified 21 and 22 are subjected to frequency analyses 31 and 32 respectively, a phase difference PHIi between input sound waves is detected 71 for each frequency component and compared 72 with a reference phase difference signal phii and the phase difference PHIi being within a set allowable range is sent to a phase shift circuit 43, while frequency data OMEGAi thereof are sent to selector circuits 51 and 52. The circuit 43 shifts, by the phase difference PHIi the phase of an output of a complex FFT analysis circuit 32 which is determined as being within an allowable range, so as to it be of the same phase with a frequency component of a complex FFT analysis circuit 31, and sends it to the circuit 52. The circuits 51 and 52 select only frequency components corresponding to the data OMEGAi and output them while a phase difference between outputs of the two sound receivers 11 and 12 holding the phase difference in a desired azimuth within an allowable range is made zero. They are subjected to reverse complex FFT respectively, converted 61 and 62 into signals in a time domain and subjected to addition and amplification 75, so as to drive a loudspeaker 76.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a directional hearing device, and more particularly to a directional hearing device that listens to sound waves emitted by an object and measures the direction of the object.

[Conventional technology]

BACKGROUND ART Sound listening devices such as sonar devices that detect the direction of arrival of sound waves and search for objects underwater, and superdirectional microphone devices that collect aerial sound are well known.

Conventionally, devices for detecting the direction of arrival of this type of sound wave are generally configured with a plurality of sound receivers, phase-shift-synthesize the output electrical signals of the sound receivers to create a directional beam, and generate a directional beam. A method was used to determine the direction of an object through This method has the drawback that for signals with one low frequency, the directional beam spreads and the directional accuracy decreases, and a large receiver array was required to solve this problem. .

[Problem to be solved by the invention]

Direction finding using the conventional directional beam described above changes the characteristics of the directional beam depending on the nine frequencies due to its operating principle. In the microphone device,
The disadvantage is that the directionality of low frequencies is poor.

[Means to solve the problem]

The device of the present invention is a directional sounding device that measures the direction of an object by listening to sound waves emitted by an object using a plurality of arrayed sound receivers, and provides a reference between the arrayed sound receivers for input from a desired measurement direction. Compare the phase difference with the measured phase difference, extract only those whose difference falls within the allowable range, and then add and synthesize the phase difference between the array sound receivers with the phase difference set to zero to obtain the audible sound output in the desired measurement direction. have

Further, the apparatus of the present invention has a configuration in which the comparison between the reference phase difference and the measured phase difference between the arrayed sound receivers is performed in the frequency domain, and the addition and synthesis is performed in the time domain.

〔Example〕

Next, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. The embodiment shown in FIG. 1 is based on the case where two sound receivers are used. , a reference phase generation circuit 74 that outputs a reference phase signal corresponding to the specified direction based on the output of the direction dial 73, and a reference phase generation circuit 74 that outputs a reference phase signal corresponding to the designated direction, and It comprises a summing amplification circuit 75 that adds and amplifies output signals, and a loudspeaker 76 driven by the output of the summing amplification circuit 75.

The signal processing unit 30 also includes complex FFT analysis circuits 31 and 32 that perform frequency analysis of the output of the sound receiver 11 and 12 by complex fast Fourier transform for four-frequency domain processing;
A phase difference detection circuit 71 detects a phase difference for each frequency component analyzed based on the outputs of the FT analysis circuits 31 and 32.
and the output of the phase difference detection circuit 7e and the reference phase generation circuit 74
A phase comparison circuit 72 that compares the phase with the reference phase output by the input sound wave and outputs the phase difference and frequency component of the input sound wave within the tolerance value.
Based on the output of the phase shift circuit 43 and the 1 phase comparison circuit 72, which shifts the output of the complex FFT analysis circuit 32 so as to make the phase difference zero in response to the output of the 9 phase comparison circuit 72, the frequency for the desired direction is determined. A selection circuit 51 for selectively extracting components.
52 and the inverse complex F with the selected signal as a time domain signal.
FT circuits 61 and 82.

Next, the operation of this embodiment will be explained. Before starting to explain the specific operation of the embodiment based on FIG.
The operating principle of the present invention will be explained with reference to the drawings.

The receivers 11.12 are arranged at a spacing 2a.

Assume that an incoming sound wave 50 is incident on these two sound receivers at an incident angle θ as shown in FIG.

In this case, the phase of the sound waves arriving at both of the nine sound receivers is expressed by the ninth-order m with the midpoint 0 as the reference.

The phase of the sound wave arriving at the sound receiver 11 is φ8. = (ωo/C) asInθ - (1) Phase of the sound wave arriving at the sound receiver 12 φ12'' - (ωo/C) aslnθ ・(2) Therefore, the phase difference Δφ between the nine sound receivers is linear (3) Formula % Formula % In formulas (1), (2) and (3), ω0 is the angular frequency of the arriving sound wave, and C is the propagation speed of the sound wave.

In the above equation (3), it can be considered that the distance 2a between the sound receivers and the speed of sound C are constant, and the phase difference Δφ of the incoming sound waves between the sound receivers is expressed by the following equation (4).

Δφ=f(ω., θ)...(4)
In other words, the phase difference Δφ is the angular frequency ω. is expressed as a function of the incident angle θ.

Next, the phase difference between the output signals of each sound receiver is calculated as (3 ) or the exact same equation as equation (4).

Next, referring back to FIG. 1, the description of the embodiment will be continued. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and this embodiment also includes two sound receivers 11 and 12 for ease of explanation.
The following is an example of a case configured with . The outputs of the sound receivers 11 and 12 are respectively amplified by preamplifiers 21 and 22 and supplied to the signal processing section 30. In addition, the reference phase generation circuit 74
is the output signal θ of the desired direction set by the direction dial 73. is input, and based on equation (3), the following (5
) is output as a reference phase difference signal Δφ. That is.

Δφ+ = (2(IJI a/C) sinθo
``'(s) Next, details of the signal processing section 30 will be explained.

The respective sound receiver output signals amplified by the preamplifiers 21 and 22 are frequency-analyzed by the complex FFT analysis circuits 31 and 32, and the output thereof is supplied to the phase difference detection circuit 71, where each of the analyzed frequency components ω, The phase difference ΔΦ of the input sound waves is detected at each time.

The phase comparison circuit 72 compares the reference phase difference signal Δφ and the actually measured input sound wave phase difference ΔΦ1, determines whether the difference is within a prescribed tolerance value α, and selects a frequency within that range. The input sound wave phase difference ΔΦ1 of the components is output to the phase shift circuit 43, and the frequency data Ω of the frequency components within the range is output to the selection circuits 51 and 52.

The phase shift circuit 43 is a complex FFT analysis circuit 3 for the frequency component determined by the nine phase comparator circuit 72 to be within the range of the allowable value α.
2 is phase-shifted by ΔΦ1 so that the phase difference with the complex FFT analysis circuit 31 becomes zero.

That is, the signals are sent to the selection circuit 52 so that they are in the same phase.

The selection circuits 51 and 52 receive the frequency data Ω1 output from the 9-phase comparator circuit 72, and select this Ω.

Only the frequency components corresponding to are selectively outputted from the outputs of the complex FFT analysis circuit 31 and the phase shift circuit 43, respectively. In this way, the signals output from the 9 selection circuits 51 and 52 maintain the phase difference between the sound receivers in the desired direction θ within the range of the tolerance value α, and the phase difference between the outputs of the two sound receivers is set to zero. It is something.

The outputs of the selection circuits 51 and 52 are each subjected to an inverse complex FFT by inverse complex FFT circuits E31 and E62, converted into time domain signals, and supplied to a summing amplifier circuit 75.

The summing amplifier circuit 75 adds, synthesizes, and amplifies the two inputs, drives a loudspeaker 76 as an analog output obtained from the array sound receiver corresponding to a desired direction, and expresses the desired direction output by listening.

In this way, without increasing the size of the sound receiver, deterioration of low frequency characteristics can be eliminated and output in a desired direction can be accurately expressed regardless of the frequency.

In addition, in the above-mentioned embodiment, the case where there are two sound receivers was explained as an example, but even in the case where there are two or more sound receivers, it is not possible to add and synthesize the sound receivers and output them by setting the phase difference between the receivers to zero. It is clear that it is easy to implement.

〔Effect of the invention〕

As explained above, the present invention converts an input sound wave captured by an array sound receiver into a frequency domain signal, and uses the phase difference between the sound receivers for each analyzed frequency component to determine whether the signal is arriving from a desired direction. It is possible to increase the size of the receiver array by determining whether or not it is a sound wave, matching the phase of the signal in the desired direction, selecting only the frequency component in the desired direction, and then inversely converting it to a time domain signal and displaying it. This has the effect of avoiding the deterioration of low frequency characteristics of the conventional method using a directional beam, and providing highly accurate audible output regardless of the frequency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing the principle of operation of the present invention. 11.12...Sound receiver, 21.22...Preamplifier, 30...Signal processing unit, 31.32...Complex FF7
Circuit, 43... Phase shift circuit, 51.52... Selection circuit. 61.82... Inverse complex FFT circuit, 71... Phase difference detection circuit, 72... Phase comparison circuit, 73... Direction dial, 74... Reference phase generation circuit, 75... Addition amplification Circuit・76°= Loudspeaker・Shinkobentsuo Susumu Uchihara Diagram 2

Claims (1)

[Scope of Claims] 1. In a directional sounding device that measures the direction of an object by listening to sound waves emitted by an object using a plurality of arrayed sound receivers, the distance between the arrayed sound receivers in response to an input from a desired measurement direction. Compare the reference phase difference with the measured phase difference, extract only those whose difference falls within the allowable range, and then set the phase difference between the arrayed sound receivers to zero and add and synthesize L to obtain the auditory output in the desired direction. A directional listening device characterized by: 2. The directional hearing device according to claim 1, wherein the comparison between the reference phase difference and the measured phase difference between the arrayed sound receivers is performed in the frequency domain, and the addition synthesis is performed in the time domain.