Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing
Sound plays an important role in our life. It helps us to communicate with one another.
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The to and fro or back and forth motion of an object is termed as vibration.
When a tightly stretched band is plucked, it vibrates and produces sound.
When it stops vibrating, it does not produce any sound.
We see that a vibrating object produces sound. In some cases, the vibrations are easily visible to us.
But in most cases, their amplitude is so small that we cannot see them. However, we can feel them.
Sound needs a medium to travel.
When air has been removed completely, it is said that there is vacuum.
The sound cannot travel through vacuum.
Sound can travel through any solid.
For example, sound can travel through wood or metal.
The to and fro motion of an object is known as vibration. This motion is also called oscillatory motion.
The number of oscillations per second is called the frequency of oscillation.
Frequency is expressed in hertz. Its symbol is Hz.
A frequency of 1 Hz is one oscillation per second.
Amplitude and frequency are two important properties of any sound.
The loudness of sound depends on its amplitude.
When the amplitude of vibration is large, the sound produced is loud. When the amplitude is small, the sound produced is feeble.
The frequency determines the shrillness or pitch of a sound.
If the frequency of vibration is higher we say that the sound is shrill and has a higher pitch.
If the frequency of vibration is lower, we say that the sound has a lower pitch.
For example, a drum vibrates with a low frequency. Therefore, it produces a low-pitched sound.
On the other hand, a whistle has a high frequency and therefore, produces a sound of higher pitch
The sounds of frequencies less than about 20 vibrations per second (20 Hz) cannot be detected by the human ear. Such sounds are called inaudible.
On the higher side, sounds of frequencies higher than about 20,000 vibrations per second (20 kHz) are also not audible to the human ear.
Thus, for human ear, the range of audible frequencies is roughly from 20 to 20,000 Hz.
Amplitude, Time Period and Frequency of a Vibration arrow_upward
Presence of unwanted gases and particles in air is called air pollution.
Similarly, presence of excessive or unwanted sounds in the environment is called noise pollution.
Major causes of noise pollution are sounds of vehicles, explosions including bursting of crackers, machines, loudspeakers etc.
Presence of excessive noise in the surroundings may cause many health related problems.
Lack of sleep, hypertension (high blood pressure), anxiety and many more health disorders may be caused by noise pollution.
A person who is exposed to a loud sound continuously may get temporary or even permanent impairment of hearing.
The noisy operations must be conducted away from any residential area.
Noise producing industries should be set up away from such areas.
Use of automobile horns should be minimized.
TV and music systems should be run at low volumes.
Trees must be planted along the roads and around buildings to cut down on the sounds reaching the residents, thus reducing the harmful effects of noise pollution.