Sound absorption characteristic of the compound aluminum foam was investigated in this paper. The absorption coefficient of the foam was measured in different conditions by the transfer function method. Compared with the single aluminum foam, the compound aluminum foam shows a significant improvement in sound absorption if the single foam and the compound foam have a same thickness of sample and depth of air-gap. The effect of structural parameters of the compound aluminum foam on the sound absorption performance is significant. And there is a reasonable structural configuration makes the acoustic properties of the compound aluminum foam to the optimal in the usual noise frequencies area. The sound dissipation mechanisms in the compound foam are principally viscous and thermal losses when there is no air-gap backing and double-resonators resonant absorption predominantly when there is an air-gap backing.
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