Transverse Wave - When particles of a medium oscillate at their mean position perpendicular to direction of propagation of wave it is transverse wave. Eg. Light Waves Longitudinal wave - If particals of a medium oscillate about their mean position parallel to direction of propagation of wave then it is called longitudinal wave. Eg. Sound Wave Sound Waves 1. They are longitudinal wave 2. They need a medium to travel
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 Longitudinal waves
(1) The individual particles of the medium move in a direction parallel to the direction of propagation of the disturbance
(2) Compressions and rarefaction are formed 
(3) e.g. Sound waves
Transverse waves
The individual particles of the medium move about their mean positions in a direction perpendicular to the direction of Wave propagation.Crests and troughs are formed
(3) e.g. Light Waves.
Three characteristics associated with sound waves
Pitch :- How the brain. interprets the frequency of an emitted sound is called its pitch. 
Amplitude :- The magnitude of the maximum disturbance in the medium on either side of the mean value is called the amplitude.
Timber :- Timber or quality of sound is that characteristic which enables us to distinguish one sound form another having the same pitch and loudness