US Patent 7270215 Loudspeaker enclosure with damping material laminated within internal shearing brace

A loudspeaker cabinet with a laminated internal brace which has a first rigid layer coupled to a first exterior panel of the cabinet, a second rigid layer coupled to an a second exterior panel of the cabinet, and a damping layer affixed between the rigid layers where they overlap. Vibration, flexure, and expansion/contraction of the cabinet are damped by shearing forces applied to the damping layer as the rigid layers move in opposite, parallel directions.