Absolute Calibration of Condenser Transmitters

N the original design of the W e n t e 1 transmitter the effective diaphragm resonance was well above 10,000 c.p.s. T h e new design (Western Electric No. 394-Type), developed by Wente, has an effective resonance at approximately 5,000 c.p.s. It is alxmt ten times more sensitive (on a voltage-pressure basis), and more immune from effects of humidity and of barometric changes. The important external dimensions of the instrument are shown in Fig. IA. T h e response of the transmitter is defined as the ratio of the electromotive force generated to the acoustic pressure acting on the trans- I Fig. I B -- C o n t o u r dimensions of condenser t r a n s m i t t e r used for field calibration. 1 See bibliography.