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Purpose: The aim of this study was to investigate the association of the body mass index (BMI) with audiometric notches in noise exposed workers.
Materials and Methods: This study is a cross-sectional analysis performed at an academic medical center. The pure-tone audiograms and basic personal information of noise-exposed workers were retrieved from the computerized database. The associations between age, height, weight, and BMI and audiometric notches were analyzed.
Results: The audiograms of 4,598 ears from 2,299 noise-exposed workers were analyzed. Approximately one-third of the ears had notched audiograms. Subjects with left-ear notched audiograms had younger average age than subjects with right-ear notches. There was no significant association between the subjects' height and weight and audiometric notches. The mean BMIs of subjects with left-ear audiograms with notches at 4K and 6K were 25.66±3.23 and 25.09±3.30, respectively; the difference was statistically significant (t-test; p=0.022).
Conclusions: Subjects with higher BMIs tended to have left-ear audiograms with notches at 4K. BMI information may assist in predicting audiogram notch frequency, thus aiding in early detection of noise-induced hearing loss.
Submitted : 06 July 2012 Revised : 01 October 202 Accepted : 06 October 2012
Introduction
A notch at 4 kHz (4K notch) in the audiogram is a basic characteristic of noise-induced hearing loss (NIHL). According to the resonance theory, the classic 4K notch in NIHL is caused by the physiological properties of human external auditory canal[1]. McBride and Williams2 found that the 4K notch was associated with noise exposure more significantly than notches at other frequencies, and concluded that the 4K notch was valuable in diagnosing NIHL. However, Wu et al.3 and Chen and Tsai4 reported a notch at 6 kHz (6K notch) in the audiogram was more closely associated with NIHL among workers in Taiwan than was the 4K notch. The ethnic differences between the participants in these studies were thought to be the major cause of the differences in the findings. In general, Asians have a lower body mass index (BMI) for the same age than Europeans. The average BMI is 1.3 kg/m2 (±0.1) lower in Asian females and 1.4 kg/m2 (±0.1) lower in Asian males compared with their European counterparts[5]. The World Health Organization (WHO) announced an international classification of adult underweight, overweight and obesity...