The effect of wearing time on hearing protector attenuation.

The effect of wearing time on attenuation was measured for three insert protectors, the E-A-R expandable foam, the Willson premolded vinyl with double flange, and the Bilsom soft polyethylene encapsulated glass fiber. Binaural detection thresholds in quiet were measured with and without the protectors worn at the initial insertion and after a period of one to one and one-half hours during which lunch was eaten. The difference between the open and closed ear thresholds provided a measure of attenuation. The subjects were 12 normal adults aged 20 to 37 years. Each participated in the three hearing protector conditions. The stimuli used were one-third octave noise bands centered at 500 Hz and 3150 Hz. The results showed that wearing time may reduce attenuation by as much as 10 dB, depending on the type of protector chosen.