RESUMO
The present study aims to identify the objective tests that can identify hidden hearing loss in a group of individuals exposed to occupational noise, which is not otherwise evident as a clinically relevant permanent threshold shift. A standard group comparison design was used to study the hidden auditory effect of occupational noise on traffic police officers. A total of 50 participants (n = 25 exposed to occupational noise; n = 25 non-occupational noise-exposed) were included in the study. The test battery comprised of behavioral tests (hearing thresholds from 250 to 16,000 Hz), fine structure Distortion product otoacoustic emissions (DPOAE's) as physiological measure, Click and CE-chirp® evoked auditory brain stem response (ABR) as electrophysiological, and Gap detection test (GDT) and Temporal modulation transfer function (TMTF) as psychophysical measures. Among the measures evaluated, extended high-frequency audiometry, fine structure DPOAE amplitude, CE-chirp® ABR, GDT, and TMTF showed a significant difference (p < 0.05) between the traffic police individuals exposed to occupational noise and the controls. However, routine audiometry and click-evoked ABR did not show any significant differences. The high-frequency audiometric thresholds, fine structure DPOAEs, CE-chirp® evoked ABR, GDT and TMTF have been shown to be affected in individuals exposed to occupational noise. This finding indicates a hidden hearing loss in the study group. Hence, this study paves the way for early identification and intervention of noise-induced hearing loss by including these measures along with routine test protocol in susceptible individuals.
RESUMO
The present study attempted to determine the effect of practicing yoga on functioning of sacculo-collic pathway using cervical vestibular evoked myogenic potential (cVEMP). cVEMP was recorded from 40 participants (20 who practice yoga regularly and 20 who do not practice yoga regularly). The differences in amplitude of P1, N1, P1-N1 complex, asymmetry ratio and latencies of P1 and N1 of cVEMP were compared between both the groups. The results of the study showed that there was a significant increase (p < 0.05) in the amplitude of P1, N1 and P1-N1 complex and a significant reduction in latency (p < 0.05) for experimental group. The asymmetry ratio in individuals who practice yoga was significantly lower (Mean = 6.73) compared to the control group (Mean = 19.13). Multivariate regression analyses suggested that the number of years of yoga practice significantly predicted the amplitude of P1-N1 complex (ß = 0.70, p < 0.01) and amplitude ratio (ß = 0.72, p < 0.01). Thus, practicing yoga improves postural control and strengthens the muscles and vestibular system leading to enhanced cVEMP responses. The plastic changes in the vestibular system and increased muscular strength because of constant practicing of yoga could have led to changes in cVEMP responses. However, further studies on a larger group of individuals are essential for better clinical applicability of the results.
