MOVING-COIL TELEPHONE RECEIVERS AND MICROPHONES

A description is given of a moving-coil head receiver and a microphone designed particularly for high quality transmission. The instruments have a substantially uniform response from 40 to 10,000 c.p.s. This uniformity of response has been obtained, without sacrifice of sensitivity, by the use of light moving parts and the association of special types of acoustic networks with the diaphragm. In practical use the microphone has a sensitivity about 10 db higher than that of the Western Electric 394 Condenser Microphone.