Harness, Dickey & Pierce, P.L.C.
Microphone
 A microphone includes a voice coil, a membrane and a diaphragm that has an annular convex portion encircling a central convex portion and a concentric cutout portion on the central convex portion. The membrane covers the cutout portion and extends to the periphery of the central convex portion. The combination of a properly designed cutout portion, the thickness of the membrane, the materials used for the membrane and the diaphragm, and the adhesive method employed to connect the membrane and the diaphragm shall result in a microphone that is capable of delivering high quality sound. 
H
H04R
inventional
Ching-Lu
Chang