Parameter calculation of sound absorption material by inversion method in pulse tube

The traditional single microphone sound pulse method is a broadband testing which measures the acoustic parameters of sound absorption material in impedance tube. However, parameter calculation needs the incident pulse and reflection pulse complete separation. This paper presents an inversion method to calculate the broadband acoustic parameters of the testing sample in pulse tube. Firstly, the pulse wave propagation model is set up in an impedance tube. The sound pressure simulated at any location of the tube is consistent with the measured value by a standard stiff terminal which is confirmed with precise accuracy by the forward calculation. Then, an acoustic model of sound absorbing material is proposed as the tube terminal reflex system and the sound pressure in the inner tube can be simulated. Finally, the model parameters are estimated by approximating the calculated sound pressure and measured sound pressure at the same location. By this way, the sound absorption performance of the test sample can be determined with single microphone using broadband pulse testing.