ORIGINAL ARTICLE

Agreement between hearing thresholds measured in non-soundproof work environments and a soundproof booth

T W Wong, T S Yu, W Q Chen, Y L Chiu, C N Wong, A H S Wong

Department of Community and Family Medicine, The Chinese University of Hong Kong

Correspondence to:
Correspondence to:
Professor Tze Wai Wong, Department of Community and Family Medicine, The Chinese University of Hong Kong, 4/F, School of Public Health, Prince of Wales Hospital, Shatin, NT, Hong Kong;
twwong{at}cuhk.edu.hk

Aims: To study the agreement between audiometric test results measured in non-soundproof environments at the worksite, and in a soundproof booth.

Methods: In a cross sectional prevalence study on noise induced hearing loss, 885 transport workers whose hearing thresholds were measured by a standard audiometric test method in non-soundproof environments at the worksite were identified to have some hearing loss (>25 dB), and were retested in a soundproof booth.

Results: At 4–8 KHz, the mean of the absolute differences in hearing threshold obtained by these two methods was 2 dB or less. When the proportions of hearing loss (30 dB for any frequencies at 3–8 KHz, or 90 dB for three low frequencies at 0.5–2 KHz, or 90 dB for three high frequencies at 3–6 KHz) were compared, considerable differences existed. A much better agreement was obtained when the criteria for hearing loss as measured in the field test under non-soundproof conditions were relaxed by 5 dB. At 4 KHz, the difference between the proportion of subjects with hearing loss as measured in the field and that as measured in the booth was the smallest. The kappa statistic was highest at 3 and 4 KHz.

Conclusions: Audiometric test results conducted in non-soundproof environments in the field are comparable to those obtained in a soundproof environment among transport workers with a hearing loss of >25 dB. The hearing threshold at 4 KHz appears suitable for the estimation of the prevalence of hearing loss when appropriate adjustments are made in the diagnostic criteria.

Keywords: agreement; noise; hearing loss; hearing threshold

Abbreviations: ANSI, American National Standards Institute; NIHL, noise induced hearing loss

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