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Evaluation by industrial workers of passive and level-dependent hearing protection devices.

Level-dependent hearing protection devices (HPDs) provide protection from intense sound, while offering amplification for speech and other signals in lower levels of noise. These HPDs have been developed in response to the communication and operational needs of noise-exposed persons in industry and the military. This study was conducted to examine industrial workers' perceptions of the performance of two level-dependent HPDs (one with integrated radio communication capability and one without it) and their customary passive HPDs. This research took place at a plastic film manufacturing plant in Rhode Island, USA, following a mixed-measures design. Fifteen maintenance technicians at the plant evaluated the two level-dependent HPDs, plus their customary passive HPDs, in three separate trial periods. Data were collected via a questionnaire designed for this purpose. Mixed-model analyses of variance were performed on all dependent measures. Linear and quadratic effect sizes were assessed with eta. Results revealed that the two level-dependent HPDs offered better perceived communication and situational awareness than the workers' customary passive HPDs. However, the level-dependent HPDs were rated lower than the passive HPDs in terms of usability and comfort. To increase workers' acceptance of level-dependent HPDs, usability issues must be addressed by the HPD manufacturers.