Sound absorption by a structure with straight rectangular tubes loaded by periodically distributed resonators

Invited paper

Jean-Philippe Groby


Tuesday 2 june, 2015, 11:20 - 11:40

0.7 Lisbon (47)

We demonstrate that the phenomenon of slow sound propagation associated with its inherent dissipation (dispersion + attenuation) can be efficiently used to design broad band sound absorbing metamaterials. The propagation in straight tubes/pores of rectangular cross-section loaded with tuned or detuned resonators is first analyzed. Below the band gap associated with the resonance, the sound speed is low inside the pores and depends on the dimensions of both the pores and the resonators. The absorption of a metamaterial consisting of a periodic arrangement of pores with different lengths and cross -sections loaded with tuned or detuned resonators is then shown to be unity or close to unity over a broad frequency range due to a correct frequency distribution of the resonances. The combination of slow sound together with the dissipation can be efficiently used to design a sound absorbing metamaterial which totally absorbs sound for wavelength much larger than four times the thickness structure and over a broadband frequency range.

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