Advanced hearing protection and auditory awareness in individuals with hearing loss

Abstract

In-ear and earmuff-type electronic protection devices are rapidly being introduced into the marketplace and deployed in noisy industrial workplaces and military settings. In these environments, workers must be sufficiently protected from noise while being able to maintain good communication abilities and situational awareness. Features such as level-dependent attenuation or amplification, user-adjustable talk-through circuitry, noise reduction, and remote communication capabilities are commonly found in advanced devices. The benefits of these features depend on their complex interaction with the signal and noise characteristics, the hearing status and language proficiency of the workers, and the nature of the auditory task. Yet, detailed electro-acoustical specifications are rarely reported by manufacturers. Measurement standards are also lacking, though the advent of ANSI/ASA S12.42 should in part address this situation. In this paper, the characteristics of two advanced devices are reported over a test battery including measurements of the passive sound attenuation, level-dependent talk-through sound transmission, and speech recognition in noise for listeners with a wide range of hearing profiles. Electronic level-dependent attenuation provided superior speech recognition performance than passive attenuation for all groups of listeners, and often exceeded unprotected speech recognition performance.