Permanent effects of noise exposure on results of a battery of hearing tests.

Industrial noise exposures may result in permanent hearing impairment caused by changes at the inner ear or cochlea. Research at the Environmental Acoustics Laboratory has shown that measurements of audiometric thresholds alone may not be an adequate indicator of hearing changes due to noise exposure, especially in the early stages of developing, noise-induced, hearing impairment. In response to this observation a battery of tests sensitive to several parameters of hearing has been developed at the Environmental Acoustics Laboratory for use in characterizing and identifying auditory effects of noise exposure. Prior to the present investigation, the use of the testing battery had been restricted to the examination of temporary, noise-induced, hearing impairments under carefully controlled laboratory conditions. The present work reports on the use of the testing battery with clinical patients known to have a history of high-level noise exposure. Generally, the usefulness of the testing battery outside of the laboratory setting and with untrained listeners was demonstrated in this investigation. Details of the procedure for presenting the testing battery components are discussed.