Beating

What it means

Beating occurs when two pitches with only slightly different frequencies sound at the same time. Instead of a stable, unified tone, a periodic swelling and fading of loudness results — an audible pulsing or throbbing.

The speed of this pulsing corresponds exactly to the difference between the two frequencies: the closer the two pitches are, the slower the beating; the farther apart they are, the faster it becomes, until it is eventually perceived as a rough sound quality of its own rather than as a distinct pulse.

Musical use

In tuning practice, beating is a central tool: instrument tuners use the beat rate to adjust intervals such as fifths or octaves precisely, slowing the beating until it disappears entirely or reaches a desired, even rate — as in well-tempered tuning, where certain fifths are deliberately tuned with a slight, controlled beat.

Beating is also used deliberately for its sound quality, for instance in the chorus effect of electronic instruments, in slightly detuned organ stops (voix céleste), or with several string players playing the same part, producing a fuller, more animated sound.

Beating should be distinguished from plain dissonance, where two pitches also sound tense but without the characteristic periodic pulsing, and from tremolo, a deliberately played rapid repetition of a single note or alternation between two notes, rather than the effect of two simultaneously sounding, slightly detuned frequencies.

Performance practice

When tuning an instrument, listen deliberately for the beating between two pitches and adjust the tuning so it slows down or disappears entirely. When playing together in a group, listening consciously for beating helps you quickly spot and correct out-of-tune notes.