Tinnitus and impulse noise-induced hearing loss in drop-forge operators.

Tinnitus is frequently accompanied by noise-induced hearing losses, and perhaps as it is assumed--particularly with those arising from exposure to impulsive types of noise. In order to explain it and to estimate a prevalence of tinnitus in the industrial, impulse noise workers the group of 261 drop-forge operators exposed to impulses with peak levels of 135 dB versus 169 age-matched controls was subjected to otological and audiometric examination, and then the complaints for tinnitus in both groups have been analysed. The prevalence of tinnitus, highest in operators with longer exposure duration (> 10 years) was found in 184 individuals (70.4%) versus 6 (3.5%) in controls. The findings closely corresponded with the degree of impulse noise-induced hearing loss. As the maximum audiometric notch was mostly localised at 6 kHz and rarely at 4 kHz, consequently the approximate pitch of the tinnitus was related to the frequencies where hearing was most affected. It is concluded that impulse noise-induced tinnitus may be sometimes more severe in its effects than is hearing loss, thus it creates an additional reason for strict hearing conservation programmes.

[A permanent noise-induced shift in the auditory threshold in textile industry workers]. / Badania nad trwalym przesunieciem progu slyszenia pod wplywem halasu u pracowników przemyslu bawelnianego.

Hearing thresholds have been measured in 236 cotton weaving mill workers (124 women: average age 42.5 +/- 11.2 years, average length of employment 19.5 +/- 10.6 years and 112 men: average age 41.2 +/- 10.3 years, average length of employment 19.0 +/- 11.1 years) exposed to continuous broadband noise of the constant level of approx. 100 dB-A. 90% of subjects exhibited the permanent threshold shift characterized by a great individual variability and maximum loss at the 4 kHz frequency. Those lesions were getting enhanced with increasing length of exposure and were more serious in elder age groups. No significant differences between the hearing loss intensity in men and women were found. The development of the hearing loss is characterized by its rapid increase within 3, 4 and 6 kHz during the initial 8 years of exposure, stabilization between years 9-12 and slow moderate increase within the further 13-31 years of exposure. Those conclusions should be implemented into practice through an increase in the frequency of preventive audiometric tests in the initial period of work in exposure which has such a great impact on the development of the hearing impairment.

[Measurement of the temporary auditory threshold shift (TTS) for evaluation of the degree of noise hazard]. / Zastosowanie pomiaru czasowego przesuniecia progu slyszenia (TTS) do oceny stopnia zagrozenia halasem.

Long-term investigations of noise in coal mines enhanced the need to take measurements at work stations posing high risk of methane explosion. To facilitate evaluation of noise hazard at the workplace in coal mines, attempts have been made to apply TTS measurements. Measurements of TTS taken within 3 to 5 minutes after cessation of noise exposure in industrial conditions made it possible to evaluate equivalent sound level.