The effect of 'conditioning' on hearing loss from a high frequency traumatic exposure.
Subramaniam-M; Henderson-D; Campo-P; Spongr-V
Hear Res 1992 Feb; 58(1):57-62
The effect of high frequency, low level conditioning exposures on hearing loss from a high frequency traumatic exposure was studied in chinchillas. Animals were made monaural by surgical intervention; recording and ground electrodes were implanted and animals were allowed to recover for at least 2 weeks prior to testing. Conditioning consisted of exposure to an octave band noise centered at 4 kilohertz at 85 decibels for 6 hours per day for 10 days. One group of animals recovered for 5 days while the other group recovered for 18 hours. Animals were then exposed to a 100 decibel noise for 48 hours. A control group was exposed only to the higher decibel level. Changes in hearing were determined after 4 weeks of recovery; measurements included threshold shifts and hair cell loss. The 5 day recovery group incurred greater threshold shifts than the other two groups and greater hair cell loss than the 18 hour recovery group. The 18 hour recovery group incurred less threshold shift and less hair cell loss than the other two groups. The authors conclude that conditioning type exposures may protect the auditory system from subsequent higher level exposures; the degree of protection varies with the time course of recovery.
NIOSH-Publication; NIOSH-Grant; Noise-induced-hearing-loss; Hearing-acuity; Hearing-impairment; Laboratory-animals; Noise-exposure; Auditory-system
State University of New York, Buffalo, New York