A sound wave is a longitudinal wave , meaning the particles of the medium vibrate parallel to the direction the wave travels. This is characterized by alternating compressions (high-pressure regions where particles are close together) and rarefactions (low-pressure regions where particles are spread apart)
. Additionally, sound waves are mechanical waves because they require a medium (such as air, water, or solids) to propagate by displacing particles through mechanical vibrations. They cannot travel through a vacuum since there are no particles to transmit the vibrations
. Sound waves are also considered pressure waves because they involve fluctuations in pressure within the medium as the wave passes, detected as compressions and rarefactions by the human ear or instruments
. In summary, a sound wave is a longitudinal, mechanical, pressure wave that propagates through a medium by particle vibrations parallel to the wave's direction of travel
