Abstract: An inner decoupler for a sonar array including a linear array of hydrophones and consisting of an alternating multi-layer configuration of acoustic compliance elements in the form of acoustic baffles and acoustic non-compliance elements in the form of water or other acoustic mass-like element located between the hydrophones and the outer surface of a ship's hull. This arrangement embodies an acoustic low pass filter between the hydrophones and the hull and operates to enhance incoming signals incident to the sonar array while attenuating signals such as structure borne noise generated from the opposite or hull side of the array.

Abstract: An acoustic array for use at high hydrostatic pressures comprises an acouc isolation baffle positioned adjacent to the hull; an intermediate acoustic conditioning module supported over the isolation baffle; and an outer layer containing a plurality of hydrophone units. The acoustic isolation baffle comprises alternating layers of rigid and compliant materials bonded together in sandwich fashion, wherein the compliant layer is provided with a regular pattern of air cells. In adjoining compliant layers the pattern of air cells is translated relative to each other so that the load bearing walls of one compliant layer overlap the open cell regions of the adjacent compliant layer with only a rigid layer disposed therebetween. The acoustic conditioning module comprises spaced coverplates with spacer elements extending therebetween to form a plurality of chambers which contain viscoelastic damping elements bonded to the outer coverplate.

Abstract: An underwater acoustic array comprises an acoustic skirt baffle positioned djacent to a hull surface for reducing the transmission of shipboard noise; an acoustic conditioning module positioned over the acoustic skirt baffle; and an outer layer secured to the acoustic conditioning module and containing a plurality of hydrophone units.The acoustic conditioning module comprises inner and outer spaced coverplates; a plurality of spacer elements extending between the coverplates to form a plurality of closed chambers therebetween; and "tuned" viscoelastic damping elements secured to the outer coverplate.