The effect of low level acoustic stimulation on susceptibility to noise in blue- and brown-eyed young human subjects.
OBJECTIVE
The aim of this study was to investigate the influence of pigmentation on the reduction in temporary noise-induced threshold shift (TTS) due to low level acoustic stimulation (LLAS). A pigmentation-dependent LLAS effect on TTS could be interpreted as a strial melanocyte involvement in LLAS. It could not be explained by cochlear sensorineural structure changes only.


METHODS
Teenagers were classified according to eye color (n = 6 + 6) and exposed to music at 70 dBA 6 h per day for 9 days (LLAS). TTS was measured before, during, and after the LLAS period.


RESULTS
It was shown that LLAS reduced TTS significantly more in blue-eyed than in brown-eyed subjects. The difference in TTS remained for at least 1 wk after the cessation of LLAS.


CONCLUSIONS
It is suggested that the observed difference in LLAS effect is due to strial melanocyte differences in free radical defense. It is also possible that other cochlear antioxidant enzyme systems, responsible for inactivation of harmful oxygen radicals and simultaneously involved in melanin synthesis such as the thioredoxin reductase/thioredoxin electron transfer system are activated.
Barrenas
M L
ML
Department of Audiology, Sahlgren's Hospital, University of Gothenburg, Sweden.
Hellstrom
P A
PA
D000161:Acoustic Stimulation; D000293:Adolescent; D001299:Audiometry; D001309:Auditory Threshold; D002648:Child; D005123:Eye; D005260:Female; D006801:Humans; D008297:Male; D009622:Noise; D010858:Pigmentation