Condenser Microphones with Plastic Diaphragms for Airborne Ultrasonics, II

抄録

A detailed study is made on the condenser microphones with back plates named ‘group IA’ in Part I of the present paper.
For each back plate, the surface roughness is studied by using profilograms and the distribution function of the surface profile is obtained. Formulae for the resonance frequency, the electrostatic capacitance and the low frequency sensitivity are obtained theoretically assuming a simple model microphone with a back plate having a profile represented by the above distribution function. The formulae are found to be in fairly good agreement with the experiments.