Heat, light, electricity, water and sound, besides a number of things are provided by nature. If the five agents of nature are under control they are rather beneficial to an individual, a society or a nation. If they are in excess and go beyond the control of man or are misused by man they pollute the environment and affect the personal and social health.
That sound (or noise) too pollutes the environment may look funny to many. But it does. It may be some times imperceptible but no less harmful. City roads are full of noise from automobiles, bands, mikes and the down towns with quarrelling men and women. The elite areas like the share market are worse even than the vegetable market. The worse preys of noise pollution are the big cities like New York, London, and Shanghai that have perfect air connection with other cities. A flight a minute disturbs the whole city. Equally infested by noise are the areas by the side of a busy railway track.
That noise too is a serious pollutant is a recent research. It is based on how sound (or noise) affects human ear. It may affect even animals. Before the advent of automobiles horse carriages carried men and material. The driver won’t hit the horse. He will move the hunter in air creating sound that jarred the ears of the horse that gave a jerk to let the horse gain speed-exploiting the animals through noise pollution. The excessive pitch of the noise created by the trumpeting of an elephant or the roaring of a lion pollutes the whole atmosphere of the jungle. So does the cries of an unruly husband in a house or a residential area. It is the ear that tells whether a particular noise pollutes the environment or not. Ear and sound (or noise) has a direct relationship.
The brain activates the pituitary glands. These glands activate the thyroid and adrenal glands to excrete hormones. As it stimulates the sympathetic nervous system it indirectly influence the heart, the stomach, the pupil, blood vessels and motor nerves that control muscle reactions. Such reactions decide the response of our body to sound. Some sounds are jarring or unpleasant to the ear while some are pleasant. The unpleasant sounds create discomfort and affect the nerves. These unpleasant impacts are collectively called as noise pollution.
Almost all the cities and towns come under noise pollution. In big cities like New York, London, Calcutta and Delhi the noisy traffic is the biggest menace. In cities like New York and the capitals of European countries the noise pollution comes from the sky too because of the high frequency of aero planes. Some lower level noises like barking dogs and fighting animals during night hours are also pollutants as they disturb sleep. They can be detrimental to health in the long run. The high pitch sounds affect the ear drum and those who have to hear these constantly are more prone to losing their hearing capacity early as they ascend the age ladder. Some people do more work in noisy deteriorates the tender parts of the mid ear. It, in the long run fails to transmit sound impulses to the inner ear. The result is inefficient responses to sound.
Sound is produced by the vibrations of an object and is transmitted in the form of waves. The loudness is measured in decibels (db). A decibel is one tenth of a bell. It is the physical unit based on the weakest sound that can be caught or detected by human ear. ‘bel’ is after the name of Alexander Graham Bell who invented the telephone. The scale of decibel is logarithmic i.e. an increase of 10db. means 10 times increase. But if the increase is 20 db. It means 100 times. Thus 30 db. Would mean a 1000 times increase. A whisper is about 10 db. A decent conversation is around 20 db. While a normal talk is 30 db. To decide a noise pollution we may start with a loud conversation which is 60 db. The playing children have a noise scale of 60 to 80 db. While the traffic noise may go to 90 db. Heavy truck traffic reaches 100 db. While a motor cycle reaches105. Beat Music amplified electrically reaches 120 db. while an aircraft- a jet take off touches 120 db a jet engine (at 25m distance) is generally not less than 140 db. But the highest and the most harmful is the space vehicles launch noise that reaches 170 db. The speed at which sound travels can of course sometimes go on polluting the area it covers.
The most experienced pollution through speed is in the air media. That is how the thundering clouds deafen people when the thunder reaches the earth. The railway trains too leave their mark of sound all the way they travel. But the most injurious is the sound of aero planes that travels
to the earth passage over which they fly. When they start travelling with a speed more than 331 m per second they cross the sound barrier making a quake like vibration in the atmosphere. Supersonic speed is about 1216 km per hour.
Any way noise pollution has been increasing in different ways with the growth of urbanization. Besides taking the environmental pollution, water pollution, nuclear pollution and the depletion of ozone layer seriously the world will have to develop a culture- sophistication in life to remove or lessen noise pollution too or half the world will be partly or totally deaf in decades to come.