LAUSR

Abstract Accurate measurements of sound pressure level require regular calibration of the microphone, and closed-coupler calibration devices are commonly used. Standard acoustical couplers are designed to be used with working standard microphones, and the dimensions of many microphones do not fit a standard coupler. For example, micro-electro-mechanical system microphones are very small and often non-cylindrical in shape. This paper describes an adaptive coupler that can accommodate microphones of arbitrary cross-sectional shape. This coupler utilizes a flexible membrane of open cell foam that roughly conforms to the shape of the microphone. In contrast to a rigid enclosure, the permeability of the membrane creates an open system that is not dependent on an airtight seal. The repeatability associated with the use of this adaptive coupler is demonstrated by calibrating a small, oddly shaped microphone. It is shown that a coupler with sealed enclosure is not required to measure the sensitivity of a microphone, although the alternative introduces several compromises.