Sound absorption by a structure with straight rectangular tubes loaded by periodically distributed resonators
Invited paper
LAUM, UMR CNRS 6613
Tuesday 2 june, 2015, 11:20 - 11:40
0.7 Lisbon (47)
Abstract:
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.