Company personnel were not involved with the maintenance of the devices, and were not aware of the exposures being recorded by the volunteers. Study personnel prepared monthly summaries of exposure data for each individual and sent a printed copy of this summary to each volunteer by mail. Volunteers were advised to consult with the company industrial hygienist if they were experiencing repeated noise exposures in excess of the OSHA action level (85 dBA). In addition, a member of the study team visited the study sites several times a week to assist the volunteers with technical device problems.