Protecting the hearing-impaired worker: Speech understanding with electronic hearing protection devices

Abstract

Introduction: In many military and civilian occupations, the use of a hearing protection device (HPD) is required while working in noisy environments. When a worker has a pre-existing hearing loss, wearing traditional passive HPDs further impedes auditory communication. Our aim was to study speech understanding in noise with electronic HPDs under simulated hearing loss conditions to assess their effectiveness for use as hearing enhancement devices. Methods: Speech understanding was tested with 18 participants using the Speech Recognition in Noise Test (SPRINT). The three ear conditions were: unprotected, the wearing of an electronic earmuff (3M PELTOR Tactical 6–S), and the wearing of an electronic earplug (INVISIO V60 and an X5 headset). The two listener conditions were normal-hearing SPRINT, and simulated hearing loss SPRINT (SHL SPRINT). In the latter condition, the SPRINT audio files were digitally filtered to simulate a high-frequency hearing loss. Results: Participants obtained the highest scores with ears unprotected, especially in the SHL SPRINT condition. The external microphones of the electronic earmuff and earplug were found to have limited bandwidth, which could have reduced speech clarity and resulted in the low SPRINT scores. Discussion: The electronic HPDs did not improve speech understanding under simulated hearing loss conditions when compared to unprotected hearing. However, in noisy environments where HPDs are required, they provide a benefit over passive HPDs by reducing the risk of overprotection for the hearing-impaired worker.