Sound is a vibration that propagates as an acoustic wave through a medium such as a gas, liquid, or solid. It consists of alternating compressions and rarefactions-regions of high and low pressure-that travel through the medium as longitudinal waves, meaning the vibrations occur in the same direction as the wave's propagation
. In physical terms, sound is a mechanical disturbance from a state of equilibrium that moves through an elastic material medium. When an object vibrates, it causes the surrounding particles (like air molecules) to vibrate as well, transmitting the sound wave outward
. Humans perceive sound when these waves reach the ear, causing the eardrum to vibrate. These vibrations are then converted into electrical signals by the inner ear and interpreted by the brain as sound. The audible range for humans typically lies between 20 Hz and 20,000 Hz; sounds outside this range, such as ultrasound or infrasound, are inaudible to us but may be heard by other animals
. In summary, sound is both a physical wave phenomenon involving vibrations traveling through a medium and a sensory experience resulting from the brain's interpretation of these waves
