1. Longitudinal wave
In a longitudinal wave the particle displacement parallel to the direction of wave propagation. To clarify this explanation can be seen in the animation below which shows a longitudinal dimension of the field-one waves propagate into the tube. The particles do not move into the tube like a like a wave, but they simply oscillate back and forth about their respective equilibrium positions. Selecting a single particle and watch his movements. Wave was seen as movement of the compression area (for example, is a pressure wave), which moves from left to right.
For other uses of sound, see sound (disambiguation).
Sound or sound is a mechanical compression or longitudinal waves that propagate through a medium. Medium or intermediary substance can be liquid, solid, gas. So, for example, sound waves can propagate in water, coal, or air.
Most of the sound is a combination of signals, but a theoretical pure sound can be explained by the speed of oscillation or frequency measured in Hertz (Hz) and amplitude or loudness of sound with a decibel measurement.
Humans hear when sound waves are vibrations in air or other medium, to the human ear drum. Limit the frequency of sound can be heard by human ears from approximately 20 Hz to 20 kHz in general amplitude with variation in the response curve. Sound above 20 kHz is called ultrasonic and below 20 Hz is called infrasound