Determination of diffuse field sound absorption of a porous absorber from Biot parameters using simulation

Abstract

Porous sound absorbers are commonly assessed by their diffuse field sound absorption. In the test, a sample of the material, having a recommended surface area of 2.44 m by 2.74 m, is placed on the floor of a reverberation room. The average sound pressure level in the room is measured using a reference sound source and compared to the level in an empty room. Using room acoustic theory, the diffuse field sound absorption of the sample can be determined. This sound absorption is often much higher than the normal incidence sound absorption due to diffraction effects especially at lower frequencies. In this research, a hybrid simulation method is used to determine the diffuse field sound absorption from the Biot properties of the sound absorber. Statistical energy analysis is used to model the room and finite element analysis is used to simulate the material sample. Results from simulation are compared against measurement and agreement is acceptable.