Functional correlates of cochlear injury.
Clark-WW; Bohne-BA; Bohl-CD
Central Institute for the Deaf, St. Louis, Missouri 1995 Jan; :1-423
The effects of noise frequency, intensity, duration, and scheduling on the magnitude, 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 induced hearing loss as younger ears. Data collected from field studies indicated that hearing levels of US industrial workers, either newly employed or those working in low noise environments, were worse than those reported as representative of an unscreened population of Americans. Hearing levels of young individuals differed little by gender or race. However, with increasing age, hearing in white males deteriorated more severely at 3,000, 4,000, and 6,000 hertz than that observed in white females and African American males and females.
NIOSH-Grant; Noise-induced-hearing-loss; Ear-disorders; Noise-exposure; Industrial-noise; Noise-measurement; Laboratory-animals; Occupational-exposure
Research Central Inst for the Deaf 818 South Euclid St Louis, MO 63110
Final Grant Report
NTIS Accession No.
Central Institute for the Deaf, St. Louis, Missouri
Central Institute for the Deaf, Saint Louis, Missouri