Abstract: A lightweight piezoelectric microphone using a metallized piezoelectric diaphragm arcuately bowed by a boss on a slotted baffle plate held in close parallel proximity to the diaphragm is disclosed. Slotted Helmholtz resonators provide frequency response shaping and wide band noise cancellation. Electrical contact between the diaphragm and an electrical conductor is provided by a conductive, elastic material compressed by parts of the microphone housing, into electrical contact with the conductor and a metallized side of the diaphragm.

Abstract: A compact electro-acoustic transducer assembly is provided having a housing formed with an acoustic output socket extending longitudinally of the housing and at least one electro-acoustic transducer mounted on the housing in registration with the acoustic output socket. The housing is provided with an aperture for transmission of sound waves from the acoustic output of the transducer to the socket. Conductive leads are deposited on the surface of the housing for providing electrical connection between the transducer and a circuit board supporting the housing. The electrical input terminals to the transducer are surface mounted thereon for engagement against the conductive leads deposited on the housing. The transducer may be formed with a thin plate-like permanent magnet formed of a rare earth cobalt material and supported in a flux-retaining member.

Abstract: An apparatus for transmitting the wearer's voice is mounted inside a breathing mask and includes a microphone and a protective sheath substantially encasing the microphone. The protective sheath includes a thin, pliable wall which is kept in contact with the sensing diaphragm of the microphone so that, when the wearer speaks and sets the sheath wall into vibration, the vibration is directly communicated to the microphone diaphragm. In one illustrative embodiment, the sheath is formed as an integral, continuous pocket in the mask body which extends inside the mask and has an opening out of the mask.