Vibration sensitivity measurements of silicon and acoustic-gradient microphones

Abstract

Microphones are often required to record audio while in a vibration environment. Therefore, it is important to maximize the acoustic-to-vibration sensitivity of such microphones. It has previously been shown that the vibration sensitivity of a microphone is, to first order, proportional to the mass per unit area of the diaphragm including the air loading effect. Although the air loading is generally minimal for omnidirectional condenser microphones with thick diaphragms, these measurements show that it cannot be ignored for newer silicon-based micro-electro-mechanical-system (MEMS) and acoustic-gradient microphones. Additionally, since microphone vibration sensitivities are typically not reported by microphone manufacturers, nor measured using standardized equipment, the setup of an inexpensive vibration measurement apparatus and associated challenges are discussed.