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Sound.

Sound is the vibration that travel through air or another medium and can be heard when they reach person's or animal's ear. Human ear has large audible range and at the threshold of pain, the dB is roughly 1 million times greater than at the threshold of hearing. Following is the different levels of sound with examples.
Although the decibel scale is nonlinear, it is directly measurable, and sound-level meters are available for that purpose.
Sound is measured in decibels (dB) on a logarithmic scale, which means that a sound of 50dB is 100 times greater than a sound of 40dB.
Human ear hears frequencies between 20Hz and 20000Hz. This is called audible sound. Below 20Hz and above 20000Hz are inaudible sound.
Sound that are below 20Hz are called Infrasonic Sound. Sound that are above 20000Hz are called Ultrasonic Sound.
Sounds at or below 70dBA are generally considered safe. Any sound at or above 85dBA is more likely to damage your hearing over time. Researchers have found that people who are exposed over long period of time to noise levels at 85dBA or higher are at much greater risk of hearing loss.


Characteristics of Sound are:
  • Wavelength
  • Amplitude
  • Time Period
  • Frequency
  • Velocity
Sound wave is majorly classified into two types. One is Transverse waves and the other is Longitudinal waves, differentiated by the way in which wave is transmitted.

Transverse wave, motion in which all points on a wave oscillate along paths at right angles to the direction of the wave's advance.
Longitudinal waves, motion in which all points on a wave oscillate parallel to the direction of wave's advance.
Speed of Sound in Air Medium:

Speed of Sound in Liquid Medium:

Speed of Sound in Solid Medium:


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  1. UnknownJune 9, 2020 at 12:09 AM

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