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Concordant intervals have simple frequency ratios and blend smoothly; discordant intervals have complex ratios and create tension

Concept L1Foundations A · Music theory & musicianship

When two notes sound together, the ear compares their frequency ratios. Simple ratios (2:1 octave; 3:2 perfect fifth; 4:3 perfect fourth) produce concords — intervals that blend harmoniously. Complex ratios produce discords — intervals with audible roughness or tension, such as minor seconds and major sevenths. Perfect concords: octave, fifth, fourth. Imperfect concords: major and minor thirds and sixths. Discords: seconds and sevenths. Discords are not wrong — they provide tension that drives harmonic motion.

Examples

Perfect fifth (C-G): ratio 3:2 — very stable. Minor second (E-F): ratio 16:15 — sharp dissonance. Major third (C-E): ratio 5:4 — warm concord.

Assessment

Classify these intervals as perfect concord, imperfect concord, or discord: major third, minor seventh, perfect fifth, major second.

Prerequisites — understand these first

Don't confuse with

Thirds and sixths are imperfect intervals because they occur in both major and minor forms, yet their simple ratios make them pleasant sounding

Sources

“there are some intervals that sound harmonious to the ear—called concords—and some that express a certain tension or unease—called discords. This is entirely due to the relative simplicity/complexity of their ratios.”

corpus · michael-hewitt-music-theory-for-computer-musicians · chunk 17

Taught in modules

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