Chapter-III(59-80) - Pollution Control Board, Assam

EIA & RA STUDY FOR NAPHTHA SPLITTER PROJECT AT NUMALIGARH REFINERY LIMITEDBaseline Environmental Status3.9 NOISE ENVIRONMENT3.9.1 IntroductionNoise can be defined as unwanted sound or sound in the wrong place at the wrong time.Noise can also be defined as any sound that is undesirable because it interferes withspeech and hearing, is intense enough to cause hearing impairment, or is otherwiseannoying. It has an adverse impact on human beings and environment, including land,structures and domestic animals. Noise can also disturb natural wildlife and eco-systems.The noise problem arises when the ambient sound level interferes with human activities.The general perception of noise varies depending on number of factors such asindividual’s natural sensitivity/ hearing ability, past experience, time of the day, socioculturalactivities at the time of exposure to sound etc. The impact of noise at communitylevel can have different effects varying from aesthetic impairment such as annoyance to ashigh as to cause hearing impairment. The health impact of noise on individual depends onseveral source factors, viz., intensity of sound pressure level, frequency spectrum, andintermittency as well as human factors such as sex, age, health condition, occupationalexposure, etc.3.9.2 Effects of NoiseAlmost all noise problems involve three basic elements, viz., the noise source, thetransmission path, and the receptor. In environmental noise, one is usually concerned withsound propagation through air. Sound, as a disturbance propagating through air, is awave-propagating phenomenon. Sound propagation from a source to a receptor dependsupon the properties of the atmosphere and the presence of any object in the transmissionpath. Sound, during transmittance, undergoes absorption, diffraction, scattering, reflection,etc. One of the most important considerations during assessment of noise impact is theeffect of wave divergence.Environmental noise can have several effects varying from hearing loss to annoyance.Sufficiently loud noise may* cause hearing loss or health damage;* interfere with work tasks, especially those involving concentration of mind;* interfere with speech communication;* affect inter-room privacy;* interfere with sleep; and* cause annoyance.Projects & Development India Limited, Sindri Page 69 of 80