Neurological basis for the symptoms of noise-induced hearing loss.
Henderson-D; Salvi-RJ; Hamernick-RP
Personal Hearing Protection in Industry 1982; :15-33
The audiological symptoms of noise induced hearing loss in relation to the changes in the neural code leaving the cochlea were investigated. Twenty monaural chinchillas were used as experimental subjects. After establishing reliable estimates of auditory sensitivity, the animals were exposed for 5 days to an octave band of noise centered at 0.5 kilohertz and having a sound pressure level of 95 decibels. The first group of six animals was tested daily and at 40 days after exposure. A second group of six was given the same exposure and then removed from the noise, anesthetized, and the response characteristics of individual auditory nerve fibers were sampled using standard neurological techniques for VIII nerve recording. The normal response of the 361 neurons sampled from eight normal chinchillas indicated that most of the neurons had some spontaneous activity, each of the neurons had a frequency to which it was most sensitive, the response area of each neuron had essentially band pass characteristics, each of the neurons had a limited dynamic range, and they all responded in essentially the same way to tone bursts at the characteristic frequency. The findings of the experimentation indicate that there may be no simple relationship between spontaneous activity and tinnitus at the level of the auditory nerve.
NIOSH-Grant; Noise-induced-hearing-loss; Auditory-system; Noise-exposure; Laboratory-animals; Neurological-reactions
Callier Ctr/communic Disorders Callier Center 1966 Inwood Road Dallas, Tex 75235
Personal Hearing Protection in Industry
University of Texas Dallas, Richardson, Texas