Sound pollution: Noise/sound pollution is generally defined as an unwanted or undesirable sound. The release of unwanted sound in to the atmosphere is called noise pollution.
High pitch sound produced by • automobiles • machines • power plants • Trains • Helicopters • aero planes • Jets • Rockets • T.V. • sudden ratting of doors and windows • explosion of bombs • Sound of crackers etc. These are the potent sources of noise pollution.
In 1990, Nobel lawreate Robert Koch said, “A day will comes when man will have to fight merciless noise as the enemy of health and that day is not far off”. According to Dr. Vern O. Knudsen of University of California, noise like smog, is a slow agent of death. If it continues unabated for the next 30 years it could become lethal to an alarming degree.
Loudness of noise Loudness of noise is measured on a logarithmic scale called “decibel” which is denoted by dB. Mathematically the dB can be expressed as follows 1dB = 20 log10 (P/ pref) P = Measured sound pressure in dynes/cm and pref = reference sound pressure which is equal to barely audible sound taken as 0.002 dynes/cm. According to World Health Organization (WHO), a level of 45 dB is considered a safe noise level for city.
By international standard, a noise level -Up to 65 dB may be
taken as tolerable. -Above 80 dB causes noise pollution. -Above 100 dB becomes uncomfortable and -Beyond 120 dB it becomes painful
Acceptable Noise Level (in dB). Description of Area Noise Level, dB -Sensitive Areas (schools, hospitals and parks, and mosques.) 45 -Residential Area 50 -Mixed Area 60 -Commercial Area 70 -Industrial Area 75 Source: Bangladesh Environment 2000
Effects of Noise pollution: Many vehicles still use hydraulic horns. This is seriously affecting work condition and health of the people. The effects of noise on human beings can be related to physiological, behavioral and psychological responses The effects of noise on human beings can be related to physiological, behavioral and psychological responses. When we hear a loud noise the following effects are seen –
• Blood vessels constrict • The skin pales • The pupil dilates • The eyes close • The voluntary and involuntary muscles tense • Gastric secretions reduce and the blood pressure increases
Effects of Noise pollution • LOS ANGELES (November 21, 2005) -- New evidence shows that the rising level of intense underwater sound produced by oil and gas exploration, military sonar and other manmade sources poses a significant long-term threat to whales, dolphins, fish and other marine species, according to a report published today by the Natural Resources Defense Council (NRDC). • .
• In a recent study by Gary Evans (in Psychological Science, January 1998), it was found that children's health is negatively impacted by aircraft noise. The children in noisy areas were found to experience significant increases in blood presure and the stress hormones epinephrine, norepinephrine and cortisol, while the children in quiet areas experienced no significant changes.
• The immediate reactions to noise which starts at noise level of 30 to 70 dB include constriction of peripheral blood vessels with a consequent increase in blood flow to the brain, Change in breathing rate, change in muscle tension and gastrointestinal mobility; these are the non-auditory reactions. • Temporary loss in hearing at high noise levels. High or explosions may cause permanent damage. • Noise produces annoyance in human beings and can interfere with proper rest and sleep.
Reduction of Noise Pollution To control the noise source, several measures can be implemented which include – proper maintenance of vehicles, – limited use of horns, mikes and loud speakers. – Plantation of trees and construction of sound barriers can control the noise path (by reflecting and defusing noise).
• By using sound reduction device likepartitions, enclosure, custom MACHINE or noise baffles.
custom MACHINE
COVERS
COVERS
• Above all public awareness can reduce the noise pollution in the city.