JP3095653B2 - Loudness evaluation device for intermittent impact sound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudness evaluation apparatus for intermittent impact sounds applied to industrial machines such as construction machines.

[0002]

2. Description of the Related Art Conventional mechanical noise measures are taken by taking measures of noise and loudness based on the loudness of a loudness measured by a noise measuring device, and the surrounding environment is protected by reducing the loudness. Was. Normally, evaluation criteria are set in units of "phones", and the purpose of noise control was to reduce the noise to a level or less specified by law by measuring the number of noise phones.

However, with respect to unsteady noise whose sound pressure fluctuates with time, the dynamic characteristics of the sound level meter do not accurately approximate the dynamic characteristics of the human hearing period. There was a case where a problem that the tendency of the indicated value of the sound level meter was different occurred. Especially for intermittent impact sound, the dynamic characteristics of the sound level meter have a very large effect,
Noise measurement and evaluation that can reproduce hearing cannot be done with current sound level meters.

[0004]

There are the following problems to be solved in measuring the noise of intermittent impact sound by a conventional sound level meter. That is, as a basic measurement process of the sound level meter, as shown in FIG. 5, the sound pressure of the i-th step obtained by discretizing the sound pressure measured by the microphone at time intervals Δt is represented by P
Assuming (i), the result is divided by the reference sound pressure (P ₀ ), rendered dimensionless and squared, and finally converted to a level L _p (i) through a first-order lag-type arithmetic circuit. The time constant T of the first-order lag system is 12 in the normal Fast mode.
It is set to 5 msec. Conventionally, the magnitude of the noise level is determined based on the equivalent noise level _Leq for calculating the energy average of the sound pressure within the measurement time based on the circuit of FIG. 5, but in this method, the intermittent noise of the noise is determined. If the energy level is the same even for sounds that are completely different in rising, loudness, and duration, and are audibly different, they naturally show the same noise level, so that there is an inadequate noise evaluation technique.

The present invention has been made in view of the above-mentioned circumstances, and can evaluate the loudness (sound volume) of an intermittent sound, which conventionally depends only on human sensation and is difficult to quantify as an auditory sensation. It is an object of the present invention to provide a loudness evaluation device for impulsive intermittent sounds, which makes it possible to clarify the above noise problems and to plan and implement noise countermeasures based on human hearing.

[0006]

According to the present invention, there is provided an apparatus for evaluating the loudness of an intermittent impact sound, comprising: a measuring means for measuring the intermittent impact sound; and a passing sound pressure for each critical band of the noise measured by the measuring means. Calculating means for performing detection, envelope and level processing, and evaluating means for calculating and evaluating loudness by a hearing filter simulating human auditory characteristics based on a sound pressure level for each critical band obtained by the calculating means. The hearing filter has coefficients for each critical band.
It has integral and differential transfer characteristics that are set,
Integral loudness output via the mold transfer characteristic and the
Differential loudness output via differential transfer characteristics
Loudness of impact intermittent sound for each coastal zone based on the sum
It is characterized by performing an evaluation .

[0007]

In the measuring step, the sound pressure measured by the measuring means is immediately divided by the reference sound pressure (P ₀ ) in the i-th step discretized at the time interval Δt, and the time change is converted into an analog / digital signal. And save.

In the calculating step, a passing sound pressure waveform for each critical band is obtained from the stored data by using a band-pass filter, detected by a detector, an envelope of the waveform is obtained, and the level is further converted. .

Next, in the evaluation step, the pass level waveform for each critical band is input to the auditory characteristic device, and the loudness is calculated and evaluated by a plurality of auditory filters. Each auditory filter has a transfer characteristic that acts differentially and integratedly with respect to a temporal change in noise, and also performs a temporal masking operation (interval masking) of intermittent sounds.

These series of data processing are automatically performed, and a loudness waveform close to the actual audibility of an intermittent impact sound is calculated by noise measurement, thereby clarifying the problem of noise.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the loudness evaluation device for an intermittent impact sound according to one embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a noise measuring device for measuring mechanical noise radiated from a mechanical device.
The sound pressure data measured by the A / D converter is converted into a digital quantity by the analog / digital converter 2 and the data storage 3
Is stored. The noise measuring device 1, the analog / digital converter 2, and the data storage device 3 measure the mechanical noise of the subject and record the data.

The noise data stored in the data storage 3 is input to a digital filter 4.
The digital filter 4 includes filters F _{1 to} F ₂₄ that pass through the noise data, for example, noise components in 24 critical bands in the audible frequency range. The critical band is a frequency band that is closely related to the auditory phenomena such as human frequency discrimination, and a typical example is a total of 24 bands in the audible frequency range as shown in FIG.

From the output of the digital filter 4, a passing sound pressure waveform for each band is detected by a detector 5, and the detected volumes A ₁ , A ₂ ,..., A ₂₄ are sent to an envelope calculator 6. Can be The envelope calculator 6 obtains an envelope (envelope) of the waveform, and calculates the corresponding volume P
₁ , P ₂ ,..., P ₂₄ are output to the level calculator 7. The level calculator 7 converts the level of the sound pressure obtained by the envelope calculator 6 and outputs the converted outputs (volumes) L ₁ , L ₂ ,
.., L ₂₄ are output to the auditory characteristic device 8. This auditory characteristic device 8
Calculates the loudness H ₁ , H ₂ ,..., H ₂₄ for each critical band and outputs it to the loudness calculator 9. The loudness calculator 9 calculates the overall loudness and displays the result on the display 10.

Next, the operation of the above embodiment will be described. In the measurement step, in the i-th step discretized by the time step Δt, the sound pressure measured by the noise measuring device 1 is immediately divided by the reference sound pressure (P ₀ ), and the time change is analog / digital.
Sampling (discretization) by the digital converter 2,
The data is stored in the data storage 3. The sound pressure data stored in the data storage unit 3 is sent to an arithmetic processing system including the digital filter unit 4 and is subjected to arithmetic processing.

That is, in the calculation step, a passing sound pressure waveform for each critical band is obtained for the stored data by using a band-pass (band-pass) filter of the digital filter unit 4, detected by the detector 5, and then enveloped. Arithmetic unit 6
, An envelope (envelope) of the waveform is obtained, and the level is converted by the level calculator 7.

Next, in the evaluation step, the pass level waveform for each critical band is input to the auditory characteristic device 8, and as shown in FIG. 2, the level of the j-th critical band is L _j (i). , The intermittent sound is immediately distributed to a plurality (N) of regions, and k
In the second region, L _jk (i) is obtained, and the same number of auditory filters, that is, the first to N-th auditory filters 1
, 11n. Auditory filter 11a,
, 11n have transfer characteristics of integral type and differential type with respect to the sound pressure level as shown in FIG.
This is a characteristic that works only when the level rises.

The transmission characteristics of the auditory filters 11a,..., 11n are as follows, and each coefficient is determined for each critical band. Differential _{form: G d (s) = K} d s / {(T d s + 1) (s 2
+ 2ζω ₀ s + 1)} integral _{form: G i (s) = K} i / (T i s + 1) where, K _d, K _i is the gain constant, T _d, T _i two time constant, omega ₀ and ζ are primary These are the natural frequency and damping ratio of the delay system. As an example, the following is defined for a band with a center frequency of 1 kHz.

Kd = 2 × 10 ⁴ , Td = 0.06
(S), ω ₀ = 6,283 × 10 ² (rad / s), ζ
= 0.4 K _i = 1, T _i = 0.08 (s) The outputs of the auditory filters 11a,..., 11n are called integral and differential loudness, and h _{jk (I)} (i) and h _{jk (D)} (i).

The overall loudness is their sum h _jk
(I), and outputs a difference Δh _jk (i) from the loudness h _jk (i−1) of the (i−1) th step as a filter output. Further, as shown in FIG. 2, each auditory filter 11a,
, 11n, the loudness at the i-th step is represented by integration from the first step and initialized until a new input acts on the dispersed intermittent sound (initialization symbol w-id becomes 1). Then, what has been accumulated so far is cleared,
It is replaced with a fixed level L ₀ (for example, a background noise level).
At the same time, time step i is reset to 1.

Each region (k = 1 to k) obtained in this manner
The maximum value of the outputs h _jk (i) at N) is the threshold value, and the output values below h _jk (i) are not recognized, and the maximum value is calculated by the auditory masking characteristic that the loudness H at the J-th critical band is calculated. _j (i) is determined. As a calculation algorithm of the next loudness evaluator, for example, a weight w _j is assumed for each band, and the loudness S _H (i) of the intermittent sound is obtained by the following equation.

[0022]

(Equation 1)

Alternatively, S _H by a neural network or the like
(I) may be obtained. Since these series of data processing are automatically performed, if a noise measurement is performed, a loudness waveform close to the actual audibility of the intermittent impact sound is calculated, and the problem of the noise is clarified.

[0024]

As described above in detail, according to the present invention, a series of processing after noise measurement is automatically performed. It is now possible to evaluate the loudness of intermittent sounds that were difficult to quantify as auditory sensations, and to clarify the problem of auditory noise and to plan and implement noise countermeasures based on human auditory sensation Becomes

Conventionally, since the actual loudness with respect to intermittent sounds has not been quantified, efforts have been made to reduce the noise level with a sound level meter in noise control.
ADVANTAGE OF THE INVENTION By this invention, the new technology development for loudness suppression in consideration of hearing can be advanced, and the product which can be felt quieter with respect to a person even with the same noise level can be created.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a loudness evaluation device for an intermittent impact sound according to an embodiment of the present invention.

FIG. 2 is an internal configuration diagram of an auditory characteristic device in a j-th critical band in the embodiment.

FIG. 3 is a configuration diagram of an auditory filter in a k-th dispersion area in the auditory characteristic device of FIG. 2;

FIG. 4 is a diagram showing a frequency definition of a representative critical band in hearing applied to the embodiment of the present invention.

FIG. 5 is a configuration diagram of a signal processing device in a conventional sound level meter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Noise measuring device 2 Analog / digital converter 3 Data storage device 4 Digital filter device 5 Detector 6 Envelope computing device 7 Level computing device 8 Auditory characteristic device 9 Loudness computing device 10 Display

Claims (1)

(57) [Claims] 1. A measuring means for measuring an intermittent impact sound, a calculating means for detecting a sound pressure passing through each critical band of the noise measured by the measuring means, an envelope and a level processing, and a calculating means for obtaining the sound. and a evaluation means for calculation and evaluation of loudness by auditory filter based on the sound pressure level for each critical band simulating the human auditory characteristics to be
In the auditory filter, a coefficient is set for each critical band.
It has integral-type and differential-type transfer characteristics.
Integral loudness output through the
Based on the sum of differential loudness output via
The loudness of the impact intermittent sound was evaluated for each coastal zone.
Loudness evaluation device impulsive intermittent sound, characterized in that Nau.