The Impact of Noise Expose on the Hearing Threshold Extended High Frequency / 대한산업의학회지

ABSTRACT

OBJECTIVES: To determine how extended high frequency is affected by noise exposure and other factors that maybe have adverse effects. METHODS: Pure tone audiometry for usual frequencies (250-8000 Hz) and extended high frequencies (1000-16000 Hz) was conducted for 331 workers at a manufacturing company from 2004 to 2005. History of noise exposure, military service, tinnitus, alcohol drinking, smoking, ear diseases, and noisy hobbies were taken by interview. T-test, ANOVA, and multiple regression was conducted according to the frequency to evaluate the factors that could affect extended high frequency hearing. RESULTS: The noise-exposed group had significantly poorer hearing than the noise-unexposed in the frequency range 2000-16000 Hz. The hearing deteriorated with increasing age through all the frequencies. High frequency hearing of 14000 Hz was significantly worse in the noise-exposed group in their 30s. Noise exposure during military service had a bad effect on hearing, especially for the noise-unexposed group. Tinnitus was associated with poorer hearing in both noise-exposed and noise-unexposed groups. Workers with noisy hobbies exhibited better hearing in the noise-unexposed group, contrary to our expectation. Extended high-frequency hearing was affected by aging, ear protection, and noisy hobbies. In extended high frequency, 14000 Hz was especially related with noise exposure history. CONCLUSIONS: Extended high frequency, especially 14000 Hz, could be used as an indicator of noiseinduced hearing loss and should be considered as a screening test for workers in noisy environments.