Sound requires a medium to travel from its source to our ears. It cannot propagate in a vacuum, where there is no material medium. In everyday situations, sound waves usually travel through air, water, or other solid objects.
When a sound is produced, such as someone speaking or a musical instrument being played, it creates vibrations in the surrounding medium. These vibrations travel outward from the source in the form of longitudinal waves. In a longitudinal wave, the particles of the medium oscillate back and forth parallel to the direction of wave propagation.
As the sound waves propagate through the medium, they cause successive compressions and rarefactions of the particles. A compression is a region where the particles are pushed closer together, while a rarefaction is a region where the particles are spread out.
These compressions and rarefactions continue to travel through the medium, creating a series of alternating high-pressure and low-pressure regions. The sound waves radiate outward in a spherical pattern, expanding as they move away from the source.
When the sound waves reach our ears, they enter the ear canal and cause the eardrum to vibrate. These vibrations are then transmitted through a series of tiny bones in the middle ear, ultimately stimulating the cochlea in the inner ear. The cochlea converts the mechanical vibrations into electrical signals that are sent to the brain, where they are interpreted as sound.
So, in summary, sound waves require a material medium to propagate, and they reach our ears by traveling through air, water, or other solid objects.