Which type of wave motion is involved in sound waves?

Sound waves are classified as longitudinal waves because they involve the oscillation of particles in the medium through which they travel, vibrating in the same direction as the wave is moving. In a longitudinal wave, such as a sound wave, areas of compression and rarefaction occur; as the particles of the medium are compressed together, they create regions of high pressure (compressions), and as they move apart, they create regions of low pressure (rarefactions).

This characteristic of sound waves distinguishes them from transverse waves, where particle motion is perpendicular to the direction of wave propagation, such as how water waves move. While oscillatory and periodic refer to the nature of wave motion in general, they do not specifically describe the type of motion seen in sound waves as longitudinal does.