SU480973A1 - Method of measuring the reflection coefficient of sound from acoustic materials - Google Patents

Description

one

The invention relates to the field of acoustics and can be applied to measure the reflection coefficients of sounds from materials with different acoustic parameters in a continuous emission mode.

The known method of measuring the coefficient of sound reflection from acoustic materials by analyzing the amplitudes of the standing waves in the acoustic long waves is complex, and the measurement process is very long.

The aim of the invention is to simplify and accelerate the measurement process.

According to the proposed method, a separate measurement of the amplitudes of the incident and reflected waves is carried out by single-directional reception, and the reflection coefficient is determined by the ratio of the amplitudes of the incident and reflected waves.

The drawing shows a block diagram of a device that implements the proposed method.

The signal at the output of each of the sound receivers 1 and 2 is proportional to the sound pressure in the standing wave at the center of their location. For the sound receiver 1, the signal at its output is ignored in the dide

L-l-fx

and K. (I "and e- + Yapad, (1) / Ci- (conversion factor of the sound receiver 1;

pad - sound pressure in the falling

wave;

Y is the wave number; c is the distance from the radiator to the sound receiver;

R is the reflection coefficient; L is the distance between the radiator and

load.

The signal at the output of the sound receiver 2, respectively, is recorded as

Zl-lL -

and, K, (Rp.

(2)

+ RPn

where Kg-coefficient transform) an audio receiver 2;

/ - p a rst a n e m e d d p p e e m i k i u 1 2.

We consider Ki K2 K A device that implements the proposed method consists of two identical sound receivers 1 and 2, phase-moving circuits 3 and 4, differential amplifiers 5 and 6, detector B and 7 and logometers 9. Sound receivers 1 and 2 separated from each other by distance / less than 0.5 A, where I is the length of the sound wave, are stationary at any place of the measuring line 10 between the radiator AND the sound energy and the pickup G2, made of acoustic material.

The proposed SPOSo b is carried out as follows.

Sipnal from sound receiver 1 is directly fed to the left input of the differential amplifier 5, and to its other input. A signal is sent from the receiver 2 through a phase-moving circuit 4, which creates a phase shift and has a modulus transfer coefficient equal to WHHUQ. Sipnal on the output of the differential amplifier 5 raeen pasBoicTiH si; glaval at its inputs. In this way, only reception is performed.

waves (Pc) Similarly, using a differential amplifier 6, only the reflected wave is received. To do this, the first .differential of the differential amplifier 6. Directly sends a signal from the sound receiver 2, and to its other input - a signal from the sound receiver 1 through the phase-shifting circuit 3, just like in the first case, creating a phase shift of y1 1. And the value of the transmission coefficient. by mode; 1 unit; Thus, the actual reception of only the reflected wave (KPaa) to determine the sound reflection coefficient R, the output signals of the detectors 7 and 8 are fed to a logometer 9, which responds to the signal ratio at its inputs. Logometer 9 is calibrated with no means: but in units of sound reflectance.

Subject invention

A method for measuring the reflection coefficient of sound from acoustic materials by analyzing the amplitudes of standing waves in long acoustic lines, characterized in that, in order to simplify and speed up the measurement process, the amplitudes of the incident and reflected waves are measured separately by unidirectional reception and with respect to The amplitudes of the incident and reflected waves determine the reflection coefficient.