Appropriateness of the Method and Evaluation in Pure-tone Audiometry in the Special Periodic Health Examination of Noise-exposed Workers

Kim, Kyoo Sang; Kim, So Yeun; Cho, Young Sook; Jung, Ho Keun

Abstract

OBJECTIVE
This study was undertaken to evaluate that noise-exposed workers have been appropriately selected for the special periodic health examination and that pure-tone audiometry has been correctly applied and the results of these have been properly analyzed.
METHODS
We obtained health examination data of noise-exposed workers from 48 special periodic health examination agencies. The data consisted of special periodic health examination results and audiograms that had performed examination during the latter half of 1998. We analysed the appropriateness of the subject selection for the second special periodic health examination of noise-exposed workers, the method of pure-tone audiometry, and the evaluation of audiogram.
RESULTS
The screening performance rate is 67.65% in the special periodic health examination of noise-exposed workers. Although 34.29 persons per agency should have had a second examination according to our criteria, only 18.44 persons were actually examined. So a third of subjects were omitted. The air and bone conduction performance rate by each frequency is 75.71 %. 24.29 % persons did not have a bone conduction and were evaluated only by air conduction. The correct use rate of symbols(right, left-unmasked AC, masked AC, unmasked BC, and masked BC) recommended by ASHA(American Speech-Language-Hearing Association) was 70.36 %. Generally air conduction threshold is equal to or higher than bone conduction threshold. In the reverse case, especially if the gap is more than 10 dB(BC-AC > 10), this is considered to be incorrect. When we applied this criteria, the result indicated that it was correct in 75.46 %. The performance rate of air masking was 15.03 %, and bone masking was 26.21 %. 7 among 48 agencies diagnosed NIHL(Noise-Induced Hearing Loss) only by air conduction, 8 performed air masking and 13 did bone masking. When compared with ISO Standard(1964) and Ministry of Labor Standard, the results of evaluation(D1, D2) on hearing loss according to hearing loss type and threshold were rather low.
CONCLUSIONS
Hearing Quality Assurance Program about periodic special examination agencies and examiners will continue to be needed and also the evaluation of hearing loss should be performed and controlled using accurate criteria. This will reduce the error among examiners and results in individuals by means of a standard that is capable of being accurate and reliable.