SOUND ABSORPTIVE STRUCTURAL BLOCK WITH SEQUENCED CAVITIES

摘要

SOUND ABSORPTIVE STRUCTURAL BLOCKWITH SEQUENCED CAVITIESAbstract of the DisclosureA sound absorbing block of molded structural materialhas a sequence of internal cavities that communicate with aregion containing the sound to be suppressed through a firstelongated slot located in an exterior wall of the block. Theinternal cavities are defined by interior walls, at least one ofwhich also contains an elongated, sound-communicating slot. Eachslot and its associated cavity define an acoustical Helmholtzresonator that dissipates sound energy incident upon the slotwith an absorption peak at a natural frequency fn. The value offn for each resonator is inversely proportional the square rootof the volume of the cavity. The internal cavities are arrangedto cascade in order of decreasing stiffness beginning at thefirst slot. In one form, two sequences of cavities in a blockuse a common final cavity. Also, the exterior slots can beformed in more than one wall to absorb sound produced in multipleregions.