Trends in the development of measurement microphones

Abstract

Measurement microphones are, in principle, simple transducers that convert dynamic pressure fluctuations into an electrical output signal. The range of applications is, however, extremely wide—from measuring exceptionally low-level signals (below 0 dB; for example, measuring tiny insects) to the 190 dB signal of large rocket launches. The frequency range of interest spans from below 0.1 Hz for sonic boom measurements to 200 kHz or more for detailed investigations of very short impulses or wind tunnel scale modelling. At the same time, the individual application may mandate specific mounting conditions with specialized form factors for the microphone and associated preamplifier design. This trend towards application-specific testing has led to the development of a wide range of specialized microphones and accessories. Still, this wide variety of measurement microphones must measure accurately and be calibrated to be traceable to the basic unit of measure as, for example, defined by the SI system. This is ensured by maintaining reference to the basic IEC definition of measurement microphones in the IEC 61094 series of standards for microphones and calibration methods.