BEAT

acoustics

Description of the device

Sound waves can overlap with each other. This results in a new wave, which properties depend on component waves’ parameters. When two waves of similar but not identical frequencies overlap, a beat is created – and its intensity changes periodically from a given minimum to maximum rate.

Phenomenon

A beat is a periodical change in amplitude of a resultant vibration caused by two superposing vibrations with similar frequencies. It can be observed in all kinds of vibrations, including those caused by waves.

How to use it

Strike one of the pipes hanged on the rack. Listen to the sound it makes. Stop the vibration by touching the pipe. Repeat with another pipe. Each of them produces sounds with slightly different pitches. With quick movements, strike both pipes one after another. You will hear a sound of increasing and decreasing intensity – that’s the beat.