Abstract: An improved diaphragm material for use with an acoustical transducer, such as a moving-coil electrodynamic loudspeaker and a loud speaker containing such diaphragm, which diaphragm comprises a formed, self-supporting, woven carbon fiber cloth material optionally having a thin air sealing plastic coating thereon, the diaphragm having a sonic velocity of about 5.times.10.sup.3 or greater and an internal loss of about 0.02 or more.

Abstract: An acoustic transducer having a honeycomb-type diaphragm material, which transducer comprises a piezoelectric element and a driving element supported within a housing frame and acoustically attached by a coupling means to a honeycomb-type diaphragm, flat sheet material having a high stiffness-to-weight ratio, to provide an acoustic transducer having an efficient, well-dispersed, frequency response of shallow design and improved heat conductivity.

Abstract: A narrow-frequency band, acoustic transducer of high conversion efficiency over a narrow-frequency band, which transducer comprises: a truncated diaphragm having a depressed, circular area and a peripheral edge about the circular area and a convex cap section extending outwardly from the circular area; a vibration board adhesively secured about the peripheral edge of the diaphragm, to couple acoustically the vibration board to the diaphragm on one side; and a piezoelectric element centrally secured to the other side of the vibration board, with electrical leads to the piezoelectric element, whereby electrical energy input to the piezoelectric element provides a high decibel acoustical output about the natural resonance frequency of the vibration board.