Abstract
Noise assessment of 105 aerobic classes and hearing assessment of 33 participants were conducted to evaluate the potential risk to noise induced hearing loss (NIHL) for aerobic class goers. Hearing levels were monitored over time for four comparison groups, including “High-Risk”, “Low-Risk”, “Control with HP”, and “Control without HP” groups. The “High-Risk” group included regular aerobic class goers who attended aerobic classes with an average noise level above 85 dBA and the “Low-Risk” group those attending aerobic classes with an average noise level below 85 dBA. The “Control with HP” group included non-gym goers asked to attend one high-risk aerobic class while wearing earplugs and the “Control without HP” group those asked to attend the aerobic class without hearing protection. Each comparison group consisted of healthy male and female adults, aged between 18 to 50 years. Measurements of pure-tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAEs) were obtained from before and immediately after one aerobic class and 48 hours and 30 days following the initial post-class test. Noise levels in the majority (78%) of the 105 aerobic classes examined were found to be higher than the 85 dBA. Signs of hearing deterioration immediately after participation of aerobic classes were most evident in the reduction of the DPOAEs measures. The “High-Risk” group exhibited the greatest reduction of DPOAEs amplitudes over time. The “Control without HP” group generally exhibited a larger degree of reduction in DPOAEs amplitudes immediately after the aerobic class as compared with the “Control with HP” group. This study provided empirical evidence showing that individuals who attended aerobic classes with excessively high noise level and did not wear hearing protectors, might be at risk of developing NIHL and that DPOAEs testing was a more sensitive tool than PTA in detecting early signs of hearing deterioration related to noise exposure.