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The Hearing Threshold of Employees Exposed to Noise Generated by the Low-Frequency Ultrasonic Welding Devices

Dudarewicz A., Zaborowski K., Rutkowska-Kaczmarek P., Zamojska-Daniszewska M., Śliwińska-Kowalska M., Zamysłowska-Szmytke E., Pawlaczyk-Łuszczyńska M.

Archives of Acoustics

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2017

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Vol. 42, No. 2

199--205

EN

The aim of the study was to assess the hearing threshold levels (HTLs) in employees exposed to noise generated by low-frequency ultrasonic technological equipment in comparison with the HTLs of workers exposed to audible noise at the similar A-weighted equivalent-continuous sound pressure level. The study includes measurements of ultrasonic and audible noise at workplaces and hearing tests, i.e. conventional pure-tone audiometry and extended high-frequency audiometry. The study group comprised 90 workers, aged 41.4 ± 10.0 years (mean±SD), exposed for 17.3 ± 9.8 years to noise generated by ultrasonic devices at mean daily noise exposure level (‹LEX,8h›) of 80.6 ± 2.9 dB. The reference group consists of 156 subjects, exposed to industrial noise (without ultrasonic components) at similar A-weighted equivalent-continuous sound pressure level (‹LEX,8h› = 81.8 ± 2.7 dB), adjusted according to age (39.8 ± 7.7 years), gender and job seniority (14.0 ± 7.0 years). This group was selected from database collected in the Nofer Institute of Occupational Medicine. Audiometric hearing threshold levels in the frequency range of 0.5–6 kHz were similar in both groups, but in the frequency range of 8–12.5 kHz they were higher in the group of employees exposed to ultrasonic noise. The findings suggest that differences in the hearing threshold (at high frequencies) in analyzed groups may be due to differences in spectral composition of noise and show the need to continue the undertaken studies.

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Hearing loss in workers exposed to different type of noise

Zamysłowska-Szmytke E., Kotyło P., Bąk M., Fuente A., Śliwińska-Kowalska M.

Archives of Acoustics

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2007

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Vol. 32, No. 2

399-404

EN

It's well documented that noise damages peripheral part of the auditory tract (cochlea). Only few investigations were performed to assess central hearing disturbances caused by noise on animal. The aim of the study was to evaluate the site of hearing damage in 2 groups of individuals exposed to different types of noise. First group consisted of 62 dockyard workers exposed to impulsive noise with co-exposure to hand-arm vibration while second group included 76 bottle glass factory workers exposed to continuous steady-state noise. Results were referred to 86 control subjects exposed neither to noise nor vibrations. Pure-tone audiometry, immitance audiometry, Auditory Brainstem Response (ABR) and cognitive-event relate auditory evoked potentials (wave P-300) were performed in all subjects. Audiometric results revealed the poorest hearing level in dockyard workers among all groups. The bottle factory workers had also significant hearing impairment at high frequencies as compared to controls. Although the wave V at the ABR was prolonged in the dockyard workers this change could reflect sensorineural hearing thresholds shift and retrocochlear damage. The latency of P-300 wave was prolonged in dockyard workers exclusively suggesting a cortical effect of exposure to impulsive noise. Conclusions. Exposure to high level impulsive noise in combination with hand-arm vibration may cause hearing deficit greater than expected. Abnormalities involve peripheral and central auditory system. More observations are necessary to confirm these findings.

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Two methods of vibration perception assessing in workers exposed to hand-arm vibration

Zamysłowska-Szmytke E., Szymczak W., Śliwińska-Kowalska M.

Archives of Acoustics

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2004

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Vol. 29, no. 2

309-315

EN

It is known that vibration perception could be influenced by the device parameters and technique of measurement. The influence of confounding factors like age, weight and height on VPTs values was assessed in previous analyses in non-exposed subjects. The aim of present study was to compare the results of two techniques of vibrotactile thresholds measurement in workers exposed to hand-arm vibration. Two methods of vibration perception assessment were compared in 124 workers (21-62 years old, 1-40 years of employment) exposed mainly to hand-arm vibration during the work as: chain saw operator, pneumatic hammers operators, metal grinders, fitters, dentist technician. One method (named "standard method") has been used in Poland so far; the second one (named "according to ISO method") was established on the base of ISO Standard 13091-1-2001. The methods differed not only in technical parameters of stimuli but also in the way of normative values evaluation. In standard method there were no individual features or habits included. The results of investigation revealed that age and weight play the important role in interpretation of tests results, both in standard and according to ISO method. Moreover, standard method measurements seem to overestimate the number of subjects with recognized vibration sense abnormalities. In both methods exposure to vibration mostly could be revealed by stimuli at frequencies of 125 and 250 Hz.