A sound wave is a pattern of disturbance created by sound energy traveling away from its source.
The sound wave requires a medium to travel.
The sound waves are longitudinal waves.
There are parts in the air where the air particles are compressed together and other regions where the air particles are spread apart due to the longitudinal motion of the air particles.
The region where particles are compressed is known as compression and the region where particles are spread is known as rarefaction.
With the movement of these regions, the sound propagates as a longitudinal wave.
Hence, the sound waves in the air are longitudinal waves.