Chapter 5

Microphone Technicalities

PRESSURE MICROPHONES

If asked to make a microphone, one way to proceed would be to copy the way the ear works: Stretch a diaphragm over a sealed chamber (providing a leak, like the Eustachian tube, for pressure equalization with barometric pressure change) and measure the displacement of the diaphragm caused by the sound, converting its vibration into voltage by various means. This is the way the simplest microphones work. Compared with the ear, though, there need to be several “improvements.” One is that the ear canal provides a resonant tube in front of the eardrum, increasing the sensitivity in just one frequency range. Because we usually want our microphone to keep timbre constant, we typically want a flat ...

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