Laminated composites made of ethylene vinyl acetate copoly mer (EVA), polyethylene glycol terephthalate, polyurethane, felt, or sound-absorbing cotton are currently the most widely used sound insulation materials in automotive trims [1-3]. However, they are not effective in dealing with lowfrequency noise. According to the mass-density law, sound transmission loss (STL) = 20lg(m s ) + 20lg(f ) − 47 (wherein
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