Noise, the silent killer

Abstract

Noise, the 'unwanted sound', is now realised as one of the most important environmental hazard in the present day industrial world. Exposure to noise is imminent, spearheaded by man's casual attitude and ignorance of its effects. Thus, the indiscriminate hooting of horns and shrieking of loudspeakers continue unabated and disturb man's peace and tranquility. Noise leads to impaired hearing and causes general stress resulting in rise of blood pressure, enhanced sweating, muscle cramps, changes in cardiac functions and biorhythm, and increase in blood cortisol and cholesterol. Defence Institute of Physiology & Allied Sciences (DIPAS), DRDO, has been working towards combating noise pollution for over the last four decades for both the Defence Forces and for the civilians. In the Armed Forces, personnel are exposed to noise resulting from arms and ammunitions, gun and artillery firings, movement of heavy armoured vehicles, flying of aircraft and helicopters, engine rooms of naval ships and submarines etc. The high level of noise experienced by the personnel in their working environment is responsible for impairment in hearing functions and liable to trigger adverse reactions in extra-auditory systems. The auditory effects of noise directly influence the peripheral auditory system and the hearing function. Noise encountered by man in his occupational environment could be either loud or impulsive, of short intermittent duration or continuous noise of mixed intensities over a prolonged period. It acts as a biological stressor which results in various non-auditory system responses, leading to physiological and psychological stress. Researches on physiological and psychological effects and on performance and comfort have provided an extensive technology pool that serves as the basis of exposure guidelines, criteria and standards. Controlling noise and safeguarding hearing are important environmental issues that need to be addressed with care. The ill effects of noise on the auditory system may be alleviated by adequate hearing protection with the use of appropriate ear defenders, electronic noise reducing head sets, inhalation of carbogen (gas mixture of 5% CO 2 and 95% O 2), supplementation with antioxidants and restricted working time in noise environment as per the laid down environmental safety guidelines. These and other management techniques including use of musical sounds may also be useful in coping with the extra auditory effects of noise.