Sound transmission through multilayered shells.

Stefan Schneider (1, 2) , Pierre-Olivier Mattei (1)

1 LMA - Laboratoire de Mécanique et d'Acoustique [Marseille]
2 Knorr Bremse

The use of porous materials to reduce sound transmission through vibrating structures wasi nvestigated in this study.Measurements carried out at LMA showed that adding alayer of melamine foam to asteel plate increases the sound transmission of the treated plate in some frequencybands. Amodel wastherefore developed to predict this increase of the transmitted sound level, induced by covering av ibrating structure with ap orous material. The existence of compressional waves, where the quarter wavelength is equal to the thickness of the added layer, wasfound responsible for the increase of sound transmission at the corresponding frequencies. Biot theory and the equivalent fluid model were used to model the acoustical behavior of the porous material. With the model based on Biot theory,w hich involves heavy data processing, accurate predictions were obtained. To overcome the drawbacks of the Biot model, as impler procedure wasd eveloped for predicting the frequencyr ange in which transmission increases. Based on the surface admittance at normal incidence, avalue which can be easily determined experimentally using an impedance tube, the proposed procedure e ffi ciently predicts the frequency range in which higher sound transmission occurs.

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]

Stefan Schneider, Pierre-Olivier Mattei. Sound transmission through multilayered shells.. Acta Acustica united with Acustica, 2007, 93 (1), pp.57-62. ⟨hal-00108431⟩