Abstract
The purpose of this investigation was to determine the effect of atmospheric humidity on the hearing protection afforded by various brands of foam earplugs. The variables measured were dry earplug weight, percent moisture content (at <5%, 50%, and 80% relative humidity), and noise attenuation. Attenuation measurements were made using KEMAR. Two of the plug types were difficult or impossible to insert in the ear at high humidity, one because of its quick recovery from compression, the other because of difficulty of compressing it. Moisture content and relative humidity had significant but very small effects on attenuation. As in a previous study, frequency had the most significant effect on attenuation (plugs were more similar than different over the measured frequency range).