A Miniature Microphone for Transistorized Amplifiers
B. B. Bauer · The Journal of the Acoustical Society of America · 1953
A new magnetic microphone has been developed for use in hearing aids and communication and similar equipment which requires a small, light, medium-impedance microphone. The new microphone has a diameter of 1 inch and a thickness of 38 inch, and it weighs 10 grams. The sensitivity is high enough to override the relatively high noise level of transistors in the frequency range most useful for voice transmission.