Attenuation of earmuffs used simultaneously with safety spectacles in exposure to impulse noise

Impulse noise is particularly hazardous to the hearing of exposed individuals. In many real-life scenarios, the only protective measure used to reduce the level of impulse noise is hearing protectors. These scenarios include firing ranges. Aside from hearing protectors, shooters use personal safety spectacles. The purpose of this paper was to determine the effect of the simultaneous use of earmuffs and safety spectacles on the sound attenuation of earmuffs during exposure to impact noise. The research was completed with the MIRE method and included the determination of sound attenuation changes in five different models of earmuffs, used simultaneously with three different models of safety spectacles and prescription glasses. The impulse noise source used was a starting pistol, which generated C-weighted peak sound pressure level at a mean of 136.7 dB. The tests demonstrated that the simultaneous use of safety spectacles and earmuffs reduces the impulse noise attenuation of the earmuffs by up to 9 dB. Such sound attenuation changes occurred during simultaneous use of earmuffs with safety spectacles, which feature temples with a rectangular cross-section. The tests also demonstrated that the effect of prescription glasses on sound attenuation was unusually high; prescription glasses reduced the impulse sound attenuation of earmuffs by as much as 18 dB. Keywords: acoustics, noise protection, impulse noise, hearing protectors, earmuffs, noise attenuation