Overview
The range of human hearing is 20 Hz to 20 kHz. Exposure to loud noise can damage the hearing receptor cells in our inner ear. Researchers and clinicians have shown that noise pollution potentially drives hearing loss, tinnitus, and hypersensitivity to sound, and also cause or worsen cardiovascular disease; type 2 diabetes; sleep disturbances; stress; mental health and cognition problems, including memory impairment and attention deficits; childhood learning delays; and low birth weight. Scientists are investigating other possible links, including to dementia.
The increasing ambient noise levels in public places arise from various sources, inter-alia, industrial activity, construction activity, generator sets, loud speakers, public address systems, music systems, vehicular horns and other mechanical devices. Hence, it becomes necessary to regulate and control noise producing and generating sources with objective of maintaining the ambient air quality standard in respect of noise.
The main aim to monitor the noise pollution is to control and reduce noise at the workplace where exposure is excessive abiding by the maximum standard limits as per the established guidelines. This necessitates to investigate how loud an area is, the source of noise, how much noise an equipment generates, and its frequency in specific environment. Such information is valuable for prediction of the disturbance in the neighborhood of a machine working outdoors, assessment of the risk of hearing damage for people working close to the machine, comparison of the acoustic properties of different makes of machines tested according to the methods described in International Standard.
Different noise standards have been amended in the Environment (Protection) Rules, 1986. WHO has established noise quality guidelines considering specific environments, time base (hours) and effects ranging between 30-140 dB(A) Leq (except the hospitals treatment rooms). Suggested duration for testing is continuous sound pressure level measured from 6AM to 10PM (Day Time: 16 hours) and from 10PM to 6AM (Night Time: 8 hrs).
Different areas have been categorized into industrial, commercial, residential or silence areas / zones for implementation of noise standards..