[Application of extended high frequency audiometry in the early diagnosis of noise--induced hearing loss].
OBJECTIVE
To assess the application of 10-20 kHz audiometry in early diagnosis of noise-induced hearing loss and to explore the relationship between hearing loss and subjects' age, the exposure time as well as the noise level.


METHODS
One thousand workers with noise exposure history were examined by pure tone audiometry(0.5-20 kHz). One hundred and twenty normal subjects served as the control group.


RESULTS
The noise levels at working sites ranged from 95 to 115dB(A). Compared with the control group, noise-exposed subjects showed minor changes in the thresholds from 0.5 to 6 KHz, whereas the thresholds were elevated in the high frequency range of 10-16 kHz (P < 0.001). The incidence of ears without any response to the maximum output at the frequency range of 14 to 20 kHz was much higher (P < 0.01) than that of the control group. In the animals exposed to noise, the thresholds of 10-18 kHz increased with the aging and with increase of working time (6-10 years), but there were no significant differences among subjects exposed to the noises at different levels(P > 0.05).


CONCLUSIONS
In noise-exposed ears, the occurrence of threshold changes in the high frequency range (10 to 20 kHz) is earlier than that in the low frequency range (0.5 to 6 kHz). Aging and working time also affect the 10-20 kHz hearing thresholds. The lack of responses to maximum output and the changes in thresholds in the high frequency range (10-20 kHz) can be used as indices for the diagnosis of early noise-induced hearing loss and for the assessment of the susceptibility of the subject to noise damage.
Wang
Y
Y
Department of Otorhinolaryngology, Hospital of China First Automobile Group Corporation, Changchun 130011, China. likang_qy@faw.com.cn
Yang
B
B
Li
Y
Y
Hou
L
L
Hu
Y
Y
Han
Y
Y
D000293:Adolescent; D000328:Adult; D001299:Audiometry / Q000379:methods*; D001309:Auditory Threshold; D005260:Female; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009623:Noise, Occupational / Q000009:adverse effects