Comparisons of hearing threshold changes in male workers with unilateral conductive hearing loss exposed to workplace noise: a retrospective cohort study for 8 years
Annals of Occupational and Environmental Medicine
;
: 51-2016.
Article
in English
| WPRIM
| ID: wpr-173899
ABSTRACT
BACKGROUND:
The purpose of this study was to investigate hearing threshold changes of workers with unilateral conductive hearing loss who were exposed to workplace noise for 8-years.METHODS:
Among 1819 workers at a shipyard in Ulsan, 78 subjects with an air-bone gap ≥10 dBHL in unilateral ears were selected. Factors that could affect hearing were acquired from questionnaires, physical examinations, and biochemistry examinations. Paired t-test was conducted to compare the hearing threshold changes over time between conductive hearing loss (CHL) ear and sensorineural hearing loss (SNHL) ear.RESULTS:
The study included male subjects aged 48.7 ± 2.9, having worked for 29.8 ± 2.7 years. Hearing thresholds increased significantly in CHL ears and SNHL ears at all frequencies (0.5–6 kHz) during follow-up period (p < 0.05). The threshold change at 4 kHz was 3.2 dBHL higher in SNHL ears which was statistically significant (p < 0.05). When workers were exposed to noise levels of 85 dBA and above, threshold change at 4 kHz was 5.6 dBHL higher in SNHL ears which was statistically significant (p < 0.05). Among workers aged below 50, the threshold change values were lower in low-frequency (0.5–2 kHz) in SNHL ears, with a small range of changes, whereas in high-frequency (3–6 kHz), the range of changes was greater SNHL ears (p < 0.05). Among workers aged 50 and above, SNHL ears showed a wider range of changes in both high- and low-frequency areas (p < 0.05).CONCLUSIONS:
At high-frequencies, particularly at 4 kHz, the range of hearing threshold changes was lower in ears with conductive hearing loss than in contralateral ears. This is suggested as a protective effect against noise exposure.
Full text:
Available
Index:
WPRIM (Western Pacific)
Main subject:
Physical Examination
/
Biochemistry
/
Retrospective Studies
/
Cohort Studies
/
Follow-Up Studies
/
Ear
/
Hearing
/
Hearing Loss, Conductive
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Hearing Loss, Noise-Induced
/
Hearing Loss, Sensorineural
Type of study:
Etiology study
/
Incidence study
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Observational study
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Prognostic study
/
Risk factors
Limits:
Humans
/
Male
Language:
English
Journal:
Annals of Occupational and Environmental Medicine
Year:
2016
Type:
Article
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