Measurement by means of time filter method of acoustic impedance and coefficient of absorption for covering materials

A method is developed for study of phenomena determining sound attenuation in absorbent covering materials. A spherical sound wave is generated by an impulse source at very short intervals and is reflected by the material. Measurements are made of acoustic impedance and the coefficient of absorption for angles of incidence of 0-70 deg and frequencies of 0.2-20 KHz. The time filter method separates the directly sensed signal from the reflected signal but imposes time limits of several milliseconds for the reflected signal so that the system cannot handle high-frequency resonances or very thick covering materials.