What is Just Intonation?

Just intonation is a tuning system in which musical intervals are based on simple whole-number ratios between frequencies. These ratios correspond closely to the natural harmonic relationships found in the overtone series, producing intervals that sound very pure and consonant.

For example, in just intonation the perfect fifth is typically tuned to a frequency ratio of 3:2, and the major third is tuned to 5:4. Because these ratios align with natural acoustic relationships, the resulting chords can sound smoother and more stable than those produced in equal temperament.

Just intonation has been used in various historical tuning systems and experimental music, though it can be challenging to apply in instruments that need to change keys frequently. Many modern composers and musicians explore just intonation to achieve precise harmonic relationships and richer tonal colors beyond the standard twelve-tone tuning system.