Facts about Sound

Facts to Remember
The speed of sound is343 m/s
The audible range of sound in human beings is20 Hz to 20,000 Hz
The level of sound prolonged exposure beyond which may cause permanent hearing loss85 dB
A woman’s voice is shriller than a man’s voice because of higherPitch
The animals which produce sounds of high pitch and frequency to communicate and locate each otherDolphins and elephants
The loudness of sound is measured in Decibels
Stringed instruments have boxes attached to increase theLoudness of the sound produced
The minimum distance which is required to hear an echo17 metres
The system of sound reflection used to find the depth of oceansSONAR (Sound navigation ranging)
The phenomenon which makes the sound of an approaching train shrillerDoppler effect
Sounds cannot travel in vacuum
Sounds travel faster in metals than in air
Sonic boom occurs when a super sonic aircraft crosses the sound barrier

Differences between Sound and Light Waves

Light WavesSound Waves
Light waves do not require a medium to travel.Sound waves require a medium to travel.
The speed of light waves is 3 x 108 metres per secondSound waves travel at a speed of 332 m/sec
Light waves are electromagnetic waves.Sound waves are mechanical waves.
Variation in frequency of wave gives different colours.Variation in frequency of sound waves gives sound with different pitch.
Light waves can travel very long distancesSound waves cannot travel long distances as their energy is dissipated easily.


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