INTRODUCTION HEARING loss resulting from exposure to noise has received considerable attention in otologic literature.1 In recent years, this type of hearing loss has assumed increased importance, partly because of its position in theories of audition but principally, perhaps, because industry is coming to realize its occurrence in those members of the labor force who function in a noisy environment. There is a mass of evidence indicating that workers who spend sufficient time in sufficiently high noise levels are exposed to the possibility of incurring an irreversible hearing loss. The length of exposure time and the intensity level of the noise above which loss is imminent are not known within exact limits, nor can the probable severity of hearing loss under given conditions of exposure be predicted on the basis of present knowledge. There appear to be large differences in individual susceptibility to noise-induced hearing loss, such that it is