ABSTRACT
P. A. Wilkins conducted a field study in a manufacturing facility intended to investigate the interaction of hearing loss and hearing protection devices (HPD) with warning signal detectability. Neither normal-hearing nor hearing-impaired listeners showed any significant differences in detection of the alarm between the occluded and unoccluded conditions. The hearing-impaired listeners showed significant increases in the masked threshold, indicating a reduced ability to detect the signals for the signal centred at 3000Hz when the earplug was worn, but no significant changes in masked thresholds were found for signal centred at 1000Hz. C. Laroche et al. have developed a computer program capable of predicting masked thresholds in noise which takes into account hearing loss due to age. The experiment described herein was conducted using high stimulus levels while the subjects were wearing HPD. It is possible that enhanced bone conduction due to the use of HPDs interacted with the high stimulus levels to reduce the masked thresholds under the hearing protectors.
