Effects of User Insertion/Donning Instructions on Noise Attenuation of Aural Insert Hearing Protectors

Abstract
An experiment was performed to examine the influence of different levels of insertion instructions on the noise attenuation achieved with five common universal-fit protective earplugs. Five insertion conditions were investigated; these required earplug placement by subjects with no instruction, with auditory feedback, with manufacturers' on-package instructions, with detailed written and pictorial instructions, and with experimenter-modeled earplug insertion procedures. Attenuation data were obtained using REAT (real-ear attenuation at threshold) test procedures on 50 subjects. The results indicated that insertion-instruction strategies posed a major influence on the level of attenuation to be realized with the earplugs, and that earplugs were differential in their sensitivity to instruction. In some instances, attenuation afforded by no instruction was tripled when more comprehensive instructions were presented to the subjects.