Experimental techniques for measuring sound absorption through micro-perforated partitions

T. Bravo and C. Maury

Euronoise 2021.

E-congress celebrado del 25 al 27 de octubre de 2021.

 

Micro-perforated partitions (MPPs) are robust mid-frequency sound absorbers of practical interest in room acoustics, but also under severe environmental conditions such as in combustion chambers. Experimental characterization of their sound absorption properties is essential to validate the visco-thermal dissipation mechanisms assumed in the models. A number of measurement procedures and test set-ups are presented to estimate the absorption of single- or multi-layer MPPs undergoing acoustic or aerodynamic excitations. In particular, two-sources impedance tube techniques using four microphones enabled sound absorption and transmission measurements through small-sized MPPs under plane wave or multi-modal propagation conditions. Pressure-velocity probe techniques are also described for measuring the sound absorption properties of rigidly-backed MPPs with larger sample size. A dedicated procedure is finally presented to estimate the absorption of boundary layer noise by MPPs flush-mounted in a wind-tunnel test section. The potential and limitations of each of these methods are discussed.

 

Photograph of the transparent back face of the MPPA for determination of its vibrating response.

 

Acknowledgements This study was funded in Spain by the Spanish project TRA2017-87978-R, AEI/FEDER, UE, and the program ILINK+2018. It was supported in France by the ANR VIRTECH (ANR-17-CE10-0012-01).

 

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