Abstract:
The undisturbed sound field (the sound field that exists without the worker present) is the reference for many damage-risk criterions. The introduction of the worker and a body-mounted microphone perturbs the sound field. The resultant sound field measurement differs from that of the undisturbed sound field. A number of researchers have examined microphone placement effects, however, these have only been conducted at limited azmithual angles in free field. A series of experiments was conducted to explore the interaction of a bodily worn measurement microphone, including the reflections and shielding effects, with the undisturbed field in both reverberant and free sound fields. New data are presented with respect to microphone placement information for 10-deg angle increments for a cohort of various size subjects (male and female). The new microphone placement data were incorporated into a previously published mathematical model to determine the accuracy of a measurement conducted with a body-worn noise dosimeter. Results indicate that body-worn acoustical instruments are accurate to within (plus or minus)2.0 dB with respect to the undisturbed sound field provided the microphone is located on the shoulder of the most exposed ear.