Detection of vehicle backup alarms is critical to safety. However, many workers placed in the vicinity of such vehicles must wear hearing protection because of exposure to vehicle-produced and other noises. This article reports on a study of the effect of electronic ANR (active noise reduction) and conventional hearing protectors on vehicle backup alarm detection in a noisy setting. The study collected masked thresholds for a backup alarm in pink and red noise at 85 and 100 dBA for 12 participants immersed in a probability monitoring task and wearing a conventional passive hearing protection device (HPD, an earmuff or a foam earplugs), an active noise reduction (ANR) headset, or no HPD at all (only in 85 dBA noise). Differences were significant between HPD devices in red noise and in the 100 dBA noise level. In addition, masked thresholds in 85 dBA noise were significantly lower for the occluded conditions (wearing an HPD) than for the open-ear condition. These results may help to refute the belief among many normal-hearing workers that the use of HPDs in relatively low levels of noise compromises their ability to hear necessary workplace sounds. Well-fit HPDs did not impair, and in fact, enhanced, participants' abilities to detect the backup alarm signal in 85 dBA noise.
Abstract