Functional Correlates of Cochlear Injury: Final Performance Report

摘要

The effects of noise frequency, intensity, duration, and scheduling on themagnitude, pattern, and growth of hearing loss and structural damage were discussed. The behavioral and anatomical correlates of presbycusis in aged, but unexposed, animals were investigated. Laboratory studies were conducted in behaviorally trained chinchillas with hearing similar to humans. With continuous exposures which mimic an occupational lifetime, the amount of hearing loss measured after the first days of exposure sets the upper bound of permanent hearing loss that will be produced by that exposure. Exposures to noise on an interrupted schedule with rest periods interspersed caused less hearing loss than equal energy continuous exposures. The ear appeared to be toughened or made more resistant to subsequent noise when exposed on some interrupted schedules. Anatomical evaluation of young and old exposed ears showed that older ones were equally susceptible to noise enduced hearing loss as younger ears.