Calibrating a Microphone

Author: N.H. Crowhurst

From the measured properties of air, the pressure fluctuations in a wave can be calculated, once the particle movement is known. This makes it possible to "calibrate" a microphone of any reliable type by placing it in this known sound field and measuring its electrical output with suitable instruments.

Using a Rayleigh disk to find a microphone's response

In this way we get a calibrated microphone - one with which we can measure a sound field, by making measurements and referring to its calibration chart. From this we can measure the performance of any other item of audio equipment. This calibrated microphone is called a "secondary-standard" Another microphone in the same sound field can be compared against the secondary standard, and an absolute response obtained for it by using the secondary standard's calibration chart.