Extended high-frequency audiometry in subjects exposed to occupational noise.

OBJECTIVES: The aim of this study was to evaluate hearing in a population of industrial workers exposed to occupational noise by using both conventional and extended high-frequency (EHF) audiometry, and to compare our results with the findings from a control group. METHODS: A total of 139 industry workers exposed to noise were examined over a period of two years and 32 healthy subjects were used as controls. Conventional audiometry in the frequency range 0.25-8 kHz and EHF audiometry in the frequency range 9-20 kHz were performed. RESULTS: Thresholds in the noise-exposed group were higher than in the control group for both standard and extended high frequencies, but variability was greater in EHF. Larger differences were found in the 4,000-18,000 Hz frequency region, and especially in the 12,500-18,000 frequency zone. A statistically significant correlation between the elevation of puretone thresholds and time of exposure was found across all frequencies (from 250 to 20,000 Hz), with the exception of 10,000 Hz. CONCLUSIONS: EHF audiometry is a useful adjunct to conventional audiometry in the audiological assessment of subjects exposed to occupational noise. This test performs well in the frequency range 12,500-18,000 Hz, but there is greater variability in the results compared with conventional audiometry.