Abstract: An electret transducer including a pair of spaced electrodes, one electrode being connected to a preamplifier input, an insulator on the outer surface of the electrode connected to the preamplifier input, and a conductive layer on the other side of the insulator, whereby the conductive layer can be used to shield the electrode to reduce stray capacitance between it and other components of the transducer by connecting the conductive shield to the output of the preamplifier circuit for the transducer. Also disclosd is the use of a silicon backplate with an integrated circuit formed therein, an insulator layer thereon, a conductive layer thereon, and an electret layer thereon, the conductive layer being grounded during poling of the electret to protect the integrated circuit from damage.

Abstract: A backplate assembly for an electret transducer including a backplate, an electret layer covering one surface of the backplate, and a peripheral spacer on the same side of the backplate as the electret layer and around the entire periphery of the electret layer, the spacer being secured to the backplate by a thin layer of material of the electret layer located and compressed between the spacer and the backplate, the thin layer being substantially thinner than the electret layer. Also disclosed is using a peripheral ring to support a diaphragm spaced from a housing wall via support members extending from the ring.

Abstract: A piezoelectric film transducer useful in directly converting a digital signal into an acoustic analog signal; metallized film zones have different areas and are electrically insulated from each other; by selectively exciting different zones or groups of zones with the digital signal, different amplitudes result in the acoustic signal, depending on the area of the particular zone or the combined area of the group of zones.

Abstract: An acoustic transducer having a plurality of piezoelectric polymer films spaced apart and mounted at their peripheries upon a hollow support member, and physically connected together at center portions such that the films are parallel to each other at the center portions and diverging from each other near the peripheries.

Abstract: An electret transducer wherein a backplate is mounted between inwardly disposed surfaces of a ridge protruding from a face of a frame, a diaphragm is mounted on the ridge, and an acoustic chamber, which is partially defined by the diaphragm, diminishes in size as it becomes more remote from an opening to it.

Abstract: An acoustic transducer with a plurality of metal-coated piezoelectric polymer films as an oscillator, adjacent film pairs being physically connected near their centers.

Abstract: An effective antifouling result with respect to marine creatures such as barnacles is achieved by energizing a piezofilm layer carried on the outside of a vessel to cause mechanical vibration of the layer.

Abstract: A miniature unidirectional condenser microphone includes a diaphragm dividing a housing into first and second chambers. Each chamber communicates through a sound inlet port to the atmosphere. One of the sound inlet ports is covered by a sheet of porous, non-absorbent, hydrophobic thermoplastic material forming an acoustical resistance.