Probe microphone techniques for determining exposure to noise

Abstract

Traditional dosimeter measures, using a microphone in the sound field, provide little information about the actual noise exposure experienced by a subject wearing earplugs, earmuffs, earphones (traditional or insert), or someone exposed to a highly directional or local noise source. In these instances, the noise at the eardrum would appear to be a more useful measure, but cannot be directly compared to traditional damage risk criteria because the latter are based on measurements in a diffuse sound field. If a simple bridged-T filter network [Killion, J. Audio Eng. Soc. 27, 13–16 (1979)] correcting for the transfer function between the diffuse field and the eardrum is interposed between a flat-frequency-response probe microphone and a dosimeter, the resulting dosimeter indication can be compared directly to traditional damage risk criteria. Techniques for minimizing the potential errors in such measurements will be discussed.