Improving sound transmission loss at ring frequency of a curved panel using tunable 3D-printed small-scale resonators

An important dip in the sound transmission loss of curved panels occurs at the ring frequency. The relevance of using small-scale resonators to solve this issue is experimentally demonstrated on an air- craft sidewall panel. The effect of varying the spatial distribution of sin- gle frequency resonators (including combination with a broadband soundproofing treatment), as well as using multi-frequency resonators with a fixed spatial distribution is studied. Large improvement of the measured sound transmission loss under a diffuse acoustic field excita- tion is obtained around the ring frequency with limited added mass and very small alteration of the overall sound insulation performance.

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