Editing Longitudinal wave (section)

== Sound waves ==
{{further|Acoustic theory}}
For longitudinal harmonic sound waves, the [[frequency]] and [[wavelength]] can be described by the formula

:<math>\ y(x,t) = y_\mathsf{o}\cdot\cos\!\Bigl(\ \omega\cdot\left( t - \tfrac{\ x\ }{ c } \right)\ \Bigr)\ </math>

where:
: <math>\ y\ ~~</math>  is the displacement of the point on the traveling sound wave;[[File:Ondes compression 2d 20 petit.gif|thumb|305px|alt=Graph depicting a symmetrical wave spreading outwards from the center in all directions|Representation of the propagation of an omnidirectional pulse wave on a 2‑D&nbsp;grid (empirical shape)]]
: <math>\ x\ ~~</math>  is the distance from the point to the wave's source;
: <math>\ t\ ~~</math>  is the time elapsed;
: <math>\ y_\mathsf{o}\ </math>  is the [[amplitude]] of the oscillations,
: <math>\ c\ ~~</math>  is the speed of the wave; and
: <math>\ \omega ~~</math>  is the [[angular frequency]] of the wave.

The quantity <math>\ \frac{\ x\ }{ c }\ </math> is the time that the wave takes to travel the distance <math>\ x ~.</math>

The ordinary frequency (<math>\ f\ </math>) of the wave is given by

:<math> f = \frac{ \omega }{\ 2 \pi\ } ~.</math>

The wavelength can be calculated as the relation between a wave's speed and ordinary frequency.

:<math> \lambda =\frac{ c }{\ f\ } ~.</math>

For sound waves, the amplitude of the wave is the difference between the pressure of the undisturbed air and the maximum pressure caused by the wave.

Sound's [[Speed of sound|propagation speed]] depends on the type, temperature, and composition of the medium through which it propagates.