The oscillating variations in sound pressure (called the WAVEFORM of the sound) PROPAGATE in the form of a SOUND WAVE. See: ACOUSTIC IMPEDANCE, COMPRESSION, LAW OF SUPERPOSITION, PARTICLE VELOCITY, ...

sound waves cause air ... in which the energy of the wave travels. compressions are regions of high pressure due to particles being close together. rarefactions are regions of low pressure due ...

A longitudinal wave is one in ... being close together. rarefactions are regions of low pressure due to particles being spread further apart. In the diagram, the compression moved from left ...