Sound waves are longitudinal waves.
Sound is produced by a series of compression and rarefactions.

The wave equation applys to sound waves as well.

Sound waves need a material to travel through.

Speed of Sound

Material	Speed of Sound (approximate)
Solid	5000 m/s
Liquid	1500 m/s
Air	330 m/s

Speed of sound does not depend on pressure.
Speed of sound increases with temperature; i.e. faster in higher temperatures.

Feature of Sound	Increases with
Pitch	freqeuncy (how fast the source vibrates)
Loudness	amplitude (energy of sound wave)

The human hear can hear sound of frequencies approximately between 20Hz and 20kHz.