Characteristics of noise-induced hearing loss in gold miners

Abstract

The characteristics of Noise Induced Hearing Loss (NIHL) in gold miners of different ages and occupation types were examined and the incidence of tinnitus, vertigo/balance problems and nausea were determined. The results indicate that as a subject group these had symmetrical bilateral, mild hearing loss in the frequencies below 2000 Hz deteriorating to a moderate sloping hearing loss in the frequencies above 2000 Hz, and the loss did not demonstrate the expected “notch” at 4000 Hz that is usually found in NIHL. The average deterioration in the pure tone thresholds of gold miners was 3.5 dB at 500Hz; 2.75dB at 1000Hz, 15.37 dB at 2000Hz, 19.12 dB at 3000Hz; 20.87dB at 4000 Hz and 14.16dB at 6000 Hz for every ten years of age. The pattern of hearing loss varies for the different occupation types with machine operators being the most severely affected. The majority of tinnitus sufferers were in the age range 30-60 years and 57.8 % were in the under 60 years old category, while in the over 60 years the incidence was 4.8 %. The incidence of vertigo and nausea were found to be 27% in this population. The results of this study will equip the audiologist to better deal with diagnostic testing, successful hearing aid fitting and aural rehabilitation of this population. The study highlights the need for greater awareness and the imparting of detailed information to gold miners about the impact of noise on their hearing.