Acoustic Beats

Periodic loudness fluctuations produced when two tones of slightly different frequency interfere.

Core Principles & Analysis

• The beat rate equals the frequency difference: tones at 440 Hz and 443 Hz beat 3 times per second.
• Piano tuners listen for beats between strings to set unisons and tempered intervals precisely.
• Beats slower than roughly 15 per second are heard as pulsing loudness rather than a separate tone.