In sound waves, how do particles move relative to the wave propagation?

In sound waves, particles move longitudinally relative to the direction of wave propagation. This means that as a sound wave travels through a medium, such as air or water, the particles of that medium vibrate back and forth in the same direction as the wave is moving.

When a sound wave propagates, it creates compressions and rarefactions in the medium, and the particles oscillate along the path of the wave. This longitudinal motion is a defining characteristic of sound waves, distinguishing them from transverse waves, where particles move perpendicularly to wave propagation. The understanding of particle motion in relation to sound waves is essential in various applications, including acoustics and ultrasound imaging in sonography.