The effect of traffic noise on the hearing level of people on Karachi streets.

OBJECTIVE To study the effects of traffic noise on hearing ability of subjects prone to traffic noise exposure. METHOD A hospital based prospective study was performed comprising of 200 selected subjects significantly exposed to traffic noise. These included rickshaw drivers, traffic constables and shopkeepers in central business area. All subjects were questioned according to a Performa after which ENT examination was carried out followed by Pure Tone Audiometery. RESULTS Hearing impairment showed correlation with the duration of job when analyzed by linear regression analysis with correlation coefficient r = 0.36 (p < 0.001), Hearing impairment was 33.81 + 0.42 dB according to the duration of job (in years). CONCLUSION Subjects are perceptually exposed to potentially damaging sound pressure level in the metropolis of Karachi. It was observed that audiologically consistent noise induced hearing loss was found to be 0.42 dB per octave from 500Hz to 2000Hz per year of duration of job.