THE EFFECT OF SMOKING ON HEARING THRESHOLD

Abstract

BACKGROUND Smoking is one of the serious public health problems and has become a common tendency   worldwide. In general, approximately 1.3 billion of the worlds population consumes tobacco. When compared to nonsmokers, smokers have more risk of having bacterial and viral respiratory infections Gastrointestinal tract and bladder cancer circulatory diseases such as stroke, arteriosclerosis, aortic aneurism and multiple organ disorders. Smoking also causes sensorineural hearing loss. AIM OBJECTIVE The aim of the study is to  analyze the hearing thresholds in smokers and non smokers in male subjects in the age group of 25 to 55years, by using   Puretone audiometry. MATERIALS AND METHODS 47 healthy non-smokers and 47 smokers were selected as the study group by tobacco use questionnaire. The cases were selected after ruling out any infections or foreign body in the external auditory meatus. In a sound proof room, the audiometric thresholds were recorded by using puretone audiometer after clearly explaining the procedure. Unpairedt test and Yates and Fishers chi square tests were used to analyze the significance of difference between variables. RESULTS 33 out of 47 smokers were affected with sensorineural hearing loss and only two non-smokers were affected with sensorineural hearing loss. There is marked increase in auditory thresholds for high frequencies among smokers, which is highly significant (p0.0001). Few smokers had both high and low frequency  hearing loss. The hearing loss is directly related to the duration of smoking (p0.0001). Auditory threshold increased with  increased number of cigarettes smoked (p0.0001).  CONCLUSION Smoking causes sensorineural hearing loss in smokers in both high and low frequencies. Hearing loss  increases with the numbers of cigarettes smoked and also  increases with duration of smoking. The hearing loss may be due to the effect of Carbon monoxide in the smoke causing hypoxic damage to hair cells by producing rise in  carboxyhemoglobin. The hearing loss may also due to nicotine induce vasospasm in the blood vessels. The toxic chemicals in cigarette smoke may also play a role by causing damage to the anti oxidative mechanisms and to the vasculature of the auditory system.