Insert-type hearing protector stability as a function of controlled jaw movement

Samples of five insert-type hearing protectors (three viscose foam, one poly-flanged, and one glass fiber) were evaluated for change in attenuation as a result of 30 min of controlled jaw movement. Protected-ear, narrow-band noise thresholds were obtained at octave intervals (between 0.25 and 4.0 kHz) before and after the jaw-movement activity. Frequency and interaction effects were not significant. Protector effects were significant beyond the 0.01 level of probability that chance caused the observed differences. As a group, the viscose foam protectors were more stable than the others. The most stable protector was E.A.R., and the least stable was Bilsom Soft.