Sound is a type of longitudinal wave. As it travels through its medium, the mediums particles show areas of compression and rarefaction. Sound, at room temperature, normally travels at a speed of 343m/s. At different temperatures, sound travels at different speeds. The speed of sound is also influenced by the density and elasticity of the medium. When the frequency of sound changes as its source moves in relationship to someone listening, this is called the Doppler Effect. Read More...