Hearing Protectors, Safety Glasses and Respiratory Protective Equipment in Combination: Effect on Sound Attenuation

摘要

This study assessed the effect of other safety gear worn in combination on the attenuation afforded by earmuffs attached to a hard hat. Seventy-two males and females participated: 24 under the age of 40 years with normal- hearing, and 48 over the age of 40 years, half with normal hearing and half with bilateral high-tone hearing loss. Measurements made with the ears unoccluded, with the muffs alone, and with the muffs in combination with safety glasses, an air-purifying half mask respirator or both glasses and respirator included (1) diffuse field hearing thresholds from 0.25-8 kHz, and (2) consonant discrimination in quiet and in speech spectrum noise. Attenuation was derived by subtracting the unoccluded from the protected threshold. Muff attenuation was within 6 dB of the manufacturer's specifications but decreased by as much as 5 dB when the glasses or respirator were worn and by 9 dB with both these devices. Males achieved 3 dB higher attenuation than females. Hearing status had no effect. Consonant discrimination was significantly poorer in noise. The impaired performed more poorly when protected but there was no difference due to combination. The results demonstrated that hearing protector attenuation may be compromised when are safety gear are worn in combination. In individuals with pre-existing hearing loss, the use of hearing protectors may increase communication handicap.