Determination of acoustic absorber parameters in impedance tubes

Abstract A computer-aided test method was developed to measure the acoustic parameters of absorber specimens in impedance tubes. A specially written Windows program, implementing the single microphone fast Fourier transform method, enables quick and precise measurement of the impedance and absorption coefficient of samples at normal sound incidence. By means of specific modifications a high precision is achieved even under critical test situations. This is demonstrated in different test cases. The measured parameter of newly designed resonance absorbers (one reactive and one active) underline the improvements made. Additional care was taken to keep the system simple, robust and easy-to-use.