Abstract
To determine the suitable thickness of sound absorber which maximize the sound absorption effects in the rectangular enclosure, the analytical study identifies the interior sound field characteristics of cavity with foamed aluminum lining and the experimental verification is performed with random noise input.By using a two-microphone impedance tube, we measure experimentally the absotrption coefficient and the acoustic impedance of simple sound absorbing materials.Measured acoustical characteristics of the foamed aluminum sheet absorber are compared to recycled rubber and sponge absorbers in order to identify corresponding best-effective frequency range.Measured acoustical parameters of the test samples are applied to the theoretical analysis to predict sound pressure field in the cavity.Measured sound absorption effects are compared to predicted ones in both cases with and without foamed aluminum lining at the bottom of the cavity of the rectagular enclosure.By using the selected foamed aluminum sheet absorber, the sound absorption effects of the exterior sound field is investigated experimentally for the structural-acoustic coupled enclosure with the foamed aluminum lining in the cavity.
