Sound waves are longitudinal waves.
They cause particles to vibrate parallel to the direction of wave travel.
The vibrations can travel through solids, liquids or gases.
The speed of sound depends on the medium through which it is travelling.
When travelling through air, the speed of sound is about 340 m/s.
Sound cannot travel through a vacuum because there are no particles to carry the vibrations.
The human ear detects sound.
Sound waves enter the ear canal and cause the eardrum to vibrate.
Three small bones transmit these vibrations to the cochlea.
This produces electrical signals which pass through the auditory nerve to the brain, where they are interpreted as sound.