A sound wave is a type of longitudinal wave. In a longitudinal wave, the particles of the medium (such as air, water, or solids) vibrate parallel to the direction of wave propagation. In the case of sound waves, they are produced by the vibration or oscillation of objects, such as vocal cords or speakers, which create compressions and rarefactions in the medium.
As sound waves travel through a medium, they create areas of high pressure called compressions, where the particles are closer together, and areas of low pressure called rarefactions, where the particles are spread apart. These compressions and rarefactions propagate through the medium, carrying the energy of the sound wave from its source to the receiver.
It is worth noting that while sound waves are longitudinal waves, they can also exhibit certain behaviors associated with transverse waves when interacting with boundaries or surfaces, resulting in phenomena such as reflection, diffraction, and interference. However, fundamentally, sound waves are classified as longitudinal waves.