"Just Intonation" is a musical tuning system that uses pure whole number ratios to define the relationships between musical intervals. In this system, intervals are tuned to express the most harmonious and simple frequency ratios, resulting in pure and resonant harmonies. However, due to the nature of these ratios, it can lead to challenges when modulating between different keys.
In Just Intonation, musical intervals are tuned according to ratios of whole numbers. This tuning approach aims to achieve the most consonant and harmonious intervals by using simple ratios of frequencies. For example, the perfect fifth interval has a frequency ratio of 3:2, which means that the higher note vibrates three times for every two vibrations of the lower note.
Unlike "Equal Temperament", Just Intonation focuses on creating pure and naturally resonant harmonies. However, this system has its limitations when it comes to playing in different keys. Since each key has a unique set of intervals, modulating between keys can result in intervals that are no longer pure, causing dissonance. This makes Just Intonation more suitable for certain types of music, such as choral and acapella singing, where complex modulations are less common.
Despite its challenges, Just Intonation remains a valuable tuning system for musicians and composers seeking to achieve specific harmonic qualities and resonance. It is particularly prominent in music traditions that prioritize rich harmonies and use instruments that allow for adjustments to individual pitches, such as the human voice and certain string instruments.