JPS63120228A - Method for separating and measuring directional component of sound - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for separating and measuring the directional components of sound with respect to an arbitrary point in a closed space in which a plurality of sound sources are arranged.

[Conventional technology]

When measuring the noise in a manufacturing factory, IC can measure the sound pressure at any point using a sound level meter.

However, since a plurality of manufacturing devices that serve as sound sources are installed in a manufacturing factory, the sound level meter measures the sum of the sound pressures of each manufacturing device, and cannot measure the sound pressure of a specific manufacturing device.

Therefore, a technique is known in which the acoustic intensity method is used to measure the directionality and amplitude of sound for each frequency, thereby making it possible to know the direction and amplitude of measurement points in a plurality of sound sources.

[Problems that the invention helps solve]

If the acoustic intensity method is used as a virtual technique, it can be measured as described above if the frequencies of each sound source are different, but if the frequencies are the same, the synthesized frequency is measured, and the direction and amplitude cannot be measured.

For example, in Figure 3, if the frequencies of sound source A and sound source C are the same, the measured value will be the composite value of sound source A and sound source C, so it is impossible to know the direction and amplitude of sound source A and sound @B. Can not.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for separating and measuring directional components of sound, which makes it possible to measure the direction and amplitude of a sound source with respect to an arbitrary point in a space in which a plurality of sound sources of the same frequency are arranged.

〔problem? Ninth means and action to solve] at least 2
Measure sound pressure data at multiple points using two omnidirectional microphones and an F/F/T analyzer to obtain complex spectrum values at each measurement point.Based on the complex spectrum values, vibrations in each direction are calculated using a predetermined algorithm. It is designed to perform calculations, and by using K, it is possible to measure the direction and amplitude of a sound source of the same frequency.

〔Example〕

FIG. 1 shows an example of an apparatus for carrying out the directional component separation method of sound according to the present invention. In addition to being rotatable, an omnidirectional fixed microphone 4 constituting a sound level meter is provided at the center of rotation, and an omnidirectional mobile microphone 5 constituting a sound level meter is provided on the bar 3 to create a mobile microphone 5. is arranged to move in a circular arc around the fixed microphone 40.

The fixed microphone 4 passes through the amplifier 6 of the sound level meter to the F
-F-T analyzer (high-speed 7-tier transform analyzer) 7 A
Connected to channel 6, mobile microphone 5 is connected to F, I? through the amplifier 9 of the sound level meter.・It is connected to the B channel IO of the T analyzer 7, and the output sides of the F, F, and T analyzers 7 are connected to the computer 11, and the calculation result of the computer +1° is stored in the 70-tube disk 712. ) 1 sends stepping pulses to the stepping motor 2 via the motor driver 13.

The nine sound pressure data obtained by the fixed and mobile microphones 4.5 are amplified to ±I voltage by the amplifier 6.9 and sent to channels A and B of the F'T analyzer g and 10, respectively. The input signal is p
-p', r Analyzer 7 processes the power spectrum of the A channel δ side and a cross spectrum between the A and B channels 6.10, and transfers it to the computer 11.

Computer I IUIk transmission 1tL7t Cross spectrum fA Divide by the power spectrum of channel g to calculate the relative complex spectrum on the B channel 10 side, and calculate the relative complex spectrum by 70tB disk + 2
VC memorized.

The ratio data stored in the 70-tube disk 12 is transferred to the minicomputer, which processes the data according to an algorithm to be described later, and outputs it to the CRT 47'.

Next, the measurement method will be explained.

The device main body 1 is installed at an arbitrary position in the space to be measured, the bar 3 is rotated by the stepping motor 2, and the sound pressure is measured at each measurement point at each predetermined angle with the moving microphone 5. Measure the sound pressure at the reference point.

By setting the number to 5, it is possible to simultaneously capture the sound pressure at multiple points using two microphones.

The data is then processed using a cross spectrum based on the captured sound pressure.

For example, the complex sound pressure spectrum at the reference point is φ0) +pt+g, and the complex sound pressure spectrum at the measurement point is l
If pm l−φ0ゝ, then the cross spectrum G between the two is G! rrL is Gem == l pz l l pm
l-φ(1)-φ('), which is input to the computer 11 together with the power spectrum G8 of the reference point.

The computer 11 calculates the relative complex spectrum of the measurement point by dividing the cross spectrum GIm by the square root of the power spectrum Gzz of the reference point.

G gate/Z−=I Pal−φ℃)−φcy) Here, φ(I), φcm>Vi, the initial phase of the reference point and the measurement point, ρ, each changes with the timing of data acquisition. However, since the phase difference φ<m)−φ(s) between the two signals remains unchanged regardless of the acquisition timing, the phase difference measured at any point in time is temporarily calculated as φ(,1))=
=:Equivalent to each phase φ1(m) at the time of Q. That is, Gtm/'F4=IPm
l gφlast)−φ(,1=)=φ'(”)=+
h+, )lP*1g = 0, and by calculating the cross spectrum at each measurement point, it is possible to obtain the same effect as multi-point complex sound pressure spectrum measurement.

The relative complex spectrum is then sent to the minicomputer and processed using the algorithm described below.

Minimum two-year law below? What sound source separation algorithm did you use? explain.

A sound wave emitted from any sound source can be regarded as a plane wave at a point sufficiently VC away from the sound source. At this time, the sound pressure Pj at any point in space < x, y is Pj = ΣI xExP(iwt + 1hxx
+1kyy) - (1).

When there are *number of sound sources, it can be considered as a linear sum of contributions from each of these sound sources.

Accordingly, hxj: k, wcO5e)', ky
j: bpsINθj kd wave a and naji,
The W component of the complex spectrum of this sound pressure data is P = F; PjwXE'yCP (1ltxjx +
1ky)'y)-(3). The unknowns at this time are the incident angle θ and the amplitude tviep for each sound source, so one directional component is assumed in advance, and the individual Contribution of direction component V
By finding +, the content term disappears, making it easy to solve the equation.

In other words, if the sound pressure at any point < z, y in space is made up of the assumed sound source in the direction shown in Figure 2, then the complex light at that point is The W component P of the spectrum is (from equation 31, P = ΣPjup X E X P (i
kxj x+ 1kyj y) ---
It is expressed as (4).

From the NM complex spectrum values PM, J, (4 x NM) actually measured at any point, the contribution of the assumed sound source direction (in this case, the complex amplitude P) l is obtained. In order to find the value, it is sufficient to determine the coefficient P'W so that the square error #8 between the measured value P JI J and the equation (4) is minimized.

...(5) Value of formula (5)? In order to minimize it, the partial differential value by an arbitrary coefficient P may be set to 0. Therefore, aΣ#''/ a p a = Q machining = Σ# xp (ihx-1x4+1kyLyJ,) x
7) +414 (6) l-1 Here, the subscript is 0.1..., 1.

(6) If expressed using the Equation 7 matrix, ajL = Σ-XF (1kxj x4-1- ik
'/jy')X gXF (ihrJx4+ikg'$
)1M==number of measurement points, (xi, y4)=coordinates of measurement point (
Ax, 4y) = wave number in x direction, y direction, 4 eos θ, 4y = 41il θ4 = wave number, θ = direction angle, pHt = spectrum value of measurement point.

When each matrix and vector is expressed using capital letters A, P, and Bt, AXp=B (7). Therefore, the amplitude vector in each direction is p = ,4−'X B
... is given by (6).

Since this is the case, the amplitude in each direction can be calculated using the algorithm described above based on the critical relative complex spectrum values obtained as described above.

In the above explanation, when the input person is assumed to match the next direction, the distribution becomes linear and the amplitude value is also input, and it matches neatly.However, as the incident angle deviates from the assumed direction, the incident angle Error components are added from the vicinity to other direction components. Furthermore, the vibration value decreases as the direction deviates from the assumed direction.

Therefore, in order to accurately know the direction of the actual sound source, use the property that the assumed direction and the direction of the actual incident sound match and the amplitude value reaches its maximum at a fixed time, and gradually change the assumed direction. The direction of the sound source of %FJ can be accurately known by detecting the angle at which the amplitude is maximum by performing analysis.

〔Effect of the invention〕

Multiple sound sources with the same frequency are installed, and the direction and amplitude of the sound source can be measured at any point in the space. This makes it possible to determine the noise distribution within the manufacturing factory, which can be used as a guide for noise countermeasures. becomes.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of an apparatus for carrying out the method of the present invention, FIG. 2 is a plan view showing an assumed direction of a sound source, and FIG. 3 is a plan view showing an example of a conventional example.

Claims (1)

[Claims] A method for measuring the direction and amplitude of a sound source with respect to an arbitrary point in a space in which a plurality of sound sources exist, comprising at least two omnidirectional microphones and an F. F. Using a T-analyzer, measure at different measurement positions and measure the number of times equal to or more than the number of sound sources to obtain the complex spectrum value at each measurement point. Based on the complex spectrum value, each measurement is performed using a predetermined algorithm. A method for separating and measuring directional components of sound, characterized in that the amplitude in the direction is calculated.