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: 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.