Production of Sound

Sound is produced by a vibrating source. When an object vibrates, it disturbs the particles of the surrounding medium. These particles then transfer the disturbance to neighbouring particles, allowing sound energy to move through the medium. Examples include: a vibrating tuning fork; guitar strings; vocal cords; a loudspeaker cone; * a drum skin.

A vibration is a repeated back-and-forth motion around an equilibrium position. When a tuning fork is struck, its prongs vibrate rapidly. These vibrations push and pull nearby air particles. This produces alternating regions of: **compression — particles closer together; rarefaction** — particles farther apart. These regions travel outward as a sound wave.

Sound is a **mechanical wave*, so it needs matter through which to travel. It can travel through: gases; liquids; solids. Sound cannot travel through a perfect vacuum because there are no particles available to transfer the disturbance.

Sound transfers energy from the vibrating source to the listener. Air particles themselves do not travel all the way from the source to the ear. They mainly oscillate around their local positions.

A loudspeaker cone moves forward and backward. Forward motion compresses nearby air. Backward motion creates a rarefaction. Repeated vibration produces a continuous sound wave.