How does sound travel?
One-line takeaway
BLUF: Sound propagates as a mechanical pressure wave through a medium (air, water, solids).
A fundamental explanation of how does sound travel?
The Explanation
Sound propagates as a mechanical pressure wave through a medium (air, water, solids). Specifically, sound is a longitudinal wave: air molecules oscillate back and forth along the direction of propagation. A vibrating source (like a speaker diaphragm or vocal cords) creates alternating compressions (regions of high pressure) and rarefactions (low pressure) in the surrounding medium. These pressure variations move outward as waves. The medium's elasticity and inertia carry the oscillation – for example, when a speaker pushes air, the compressed region propagates. Sound cannot travel in a vacuum because it needs a material to carry these pressure pulses.