Auditory fatigue: retrocochlear components.
Science 1975 Oct; 190(4213):486-487
Measurements of auditory sensitivity were taken at the VIII nerve, cochlear nucleus, and inferior colliculus following a fatiguing sound exposure in chinchillas. Each animal was exposed to a standard temporary threshold shift (TTS) producing a tone of 8 minutes in duration at 95 decibels sound pressure level near the tympanic membrane. The exposure was at a frequency between 0.4 and 8.0 kilohertz. In the first experiment the auditory evoked response of the chinchillas was recorded from a chronic electrode placed over the rudimentary tentorium. In the second experiment the VIII nerve action potential and neurons from the cochlear nucleus were measured from anesthetized and tracheotomized chinchillas. In the third study the single units from the contralateral inferior colliculus were studied. The measurements indicated that low level, short duration sound exposures produced a progressively larger loss in sensitivity from peripheral to central auditory sites. These results suggested that there is a retrocochlear component to TTS. The authors conclude that different TTS exposures are likely to produce different physiological changes even though the final behavioral measurement of TTS is the same.
NIOSH-Publication; NIOSH-Grant; Noise-induced-hearing-loss; Hearing-threshold; Sensory-thresholds; Noise-exposure; Laboratory-animals
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