Britannica Sources used in this answer

How do sound waves travel through air?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Watch a suspended vibrating spring to learn about the propagation of sound waves — sound Learn about the propagation of sound waves from a point source by observing the motion of a suspended vibrating spring.

Sound travels through air as a longitudinal wave, which is a mechanical disturbance that propagates through an elastic medium. Unlike transverse waves, where motion is perpendicular to the direction of travel, longitudinal waves involve particles vibrating back and forth in the same direction the wave is moving.12

When a source creates a sound, it disturbs the surrounding air particles, causing them to oscillate. These particles push and pull on their neighbors, creating a chain reaction of alternating regions of high pressure, known as compressions, and regions of low pressure, known as rarefactions. This periodic variation in pressure moves through the air at a specific speed, which is determined by the temperature and properties of the gas.213

Because sound requires this physical interaction between particles to propagate, it cannot travel through a vacuum, as there is no medium to carry the disturbance. Under standard conditions, sound waves propagate linearly with minimal loss or change in shape, allowing us to perceive sounds like speech or music clearly.245