The effects of safety gear worn in combination and hearing loss on earmuff attenuation and speech understanding

Abstract

A study was designed to determine whether the wearing of other safety gear in combination would decrease the sound attenuation of hearing protective ear muffs. Each of 24 subjects were tested with the ears unoccluded (UN), and subsequently with Class A earmuffs attached to a hard hat (M), the muffs in combination with safety glasses (MG), the muffs in combination with an air-purifying half-mask respirator (MR), and with the muffs in combination with both the glasses and respirator (MGR). In each listening condition, diffuse field hearing thresholds were measured in quiet for eight one-third octave noise bands with center frequencies ranging from 0.25 to 8 kHz. Consonant discrimination was assessed in quiet (75 dB SPL) and in a background of 80 dB SPL speech spectrum noise. Decrements in attenuation due to the wearing other safety gear in combination with hearing protective ear muffs were no different for normal and hearing-impaired listeners.