Final answer:
Sound waves are longitudinal waves, with disturbances parallel to the direction of propagation.
Step-by-step explanation:
Sound waves are classified as longitudinal waves.
A longitudinal wave is a wave in which the disturbance or oscillation is parallel to the direction of propagation. In the case of sound waves, the disturbance is a variation in pressure, resulting in compressions and rarefactions in the medium through which the wave travels.
For example, when a sound wave travels through air, the air particles vibrate back and forth in the same direction as the wave propagates, creating areas of high pressure (compressions) and low pressure (rarefactions).