Screening protocols for the prevention of occupational noise-induced hearing loss: the role of conventional and extended high frequency audiometry may vary according to the years of employment.
BACKGROUND
Although occupational noise-induced hearing loss (NIHL) has become a major problem in industrialized societies, there is a notable lack of effective screening protocols to ensure its early diagnosis. The aim of this study was to detect a potential role of extended high frequency (EHF) audiometry in industrial hearing screening protocols.


METHODS
The population consisted of 151 persons, working for 8 hours daily in a noisy environment (90-110 dBA). The changes of hearing thresholds in industrial workers were analyzed, not only with respect to their age, as has been presented by previous studies, but also with respect to the duration of their previous employment.


RESULTS
During the first 10 years of employment, the frequencies 12500, 14000 and 16000Hz were the only ones significantly affected. For the second decade of employment, thresholds were significantly elevated only at 2000 and 4000Hz. After exceeding 20 years of employment, the affected frequencies were 250, 500 and 1000Hz. The effects of age on hearing acuity were significant at all frequencies for the first 2 groups.


CONCLUSIONS
EHF audiometry seems able to identify the first signs of NIHL, much earlier than conventional audiometry, and therefore may need to be implemented in the screening examinations especially of workers with less than 1 decade of employment. Hearing screening protocols could become more efficient by adjusting their frequency ranges according to the frequencies "at risk", which correspond to the duration of the workers' previous employment.
Riga
Maria
M
ENT Department, University Hospital of Alexandroupolis, Demokritos University of Thrace, Thrace, Greece. mariariga@hotmail.com
Korres
George
G
Balatsouras
Dimitrios
D
Korres
Stavros
S
D000328:Adult; D001299:Audiometry / Q000379:methods*; D001309:Auditory Threshold; D004651:Employment / Q000706:statistics & numerical data*; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis* / Q000517:prevention & control*; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008403:Mass Screening / Q000379:methods*; D009623:Noise, Occupational / Q000706:statistics & numerical data*; D013997:Time Factors