Hearing Threshold Level In Workers Exposed To Noise Of Ultrasonic Welding Devices

The aim of this study was to examine the audiometric hearing thresholds in the frequency range up to 16 kHz in workers exposed to audible noise and ultrasonic noise. Standard pure-tone audiometry (PTA) and extended high-frequency audiometry (EHFA) were determined in 51 operators of ultrasonic welding devices. Their exposure to (audible) noise and ultrasonic noise was evaluated according to PN-N-01307:1994, PN-EN ISO9612:2011 and prPN-Z-01209P:2019, on the basis of the results of sound pressure level measurements performed at 45 work posts of ultrasonic welders. Workers' actual hearing threshold levels (HTLs) in the frequency range up to 12.5 kHz were compared with expected HTLs calculated according to ISO1999:2013 and ISO7029:2017. These predictions were determined both for populations exposed to audible noise and those which were not exposed, consistent with the study group in terms of gender, age and exposure to noise. The results confirm the usefulness of the aforesaid standardized methods within the range of conventional audiometry. However, there is still a need to develop methods for predicting the noise-induced hearing loss in the frequency range of EHFA. The study is supported by the funds of the Polish Ministry of Health as a part of National Health Programme (project no.6/4/3.1h/NPZ/2016/312/1659/a).