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← Learn·Triad Construction as Stacked Intervals

Triads as Stacked Thirds

Builds on Interval Naming & Quality

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A triad is just two intervals of a 3rd stacked on top of each other — root, third, fifth. Which triad quality you get depends only on whether each of those two 3rds is major (4 semitones) or minor (3 semitones).

Major triad = major 3rd + minor 3rd (e.g. C-E-G). Minor triad = minor 3rd + major 3rd (e.g. C-E♭-G) — the same two interval sizes, swapped. Diminished triad = minor 3rd + minor 3rd (both small, e.g. C-E♭-G♭). Augmented triad = major 3rd + major 3rd (both large, e.g. C-E-G♯).

💡 Tip

Once you can hear the quality of the bottom 3rd (root to middle note) in isolation, you've already narrowed it down to major/augmented (major 3rd on bottom) or minor/diminished (minor 3rd on bottom) — the top 3rd tells you the rest.

⚠️ Common mistake

Trying to recognize a whole triad's sound from scratch every time instead of decomposing it into its two intervals. Since interval recognition is already trained, reuse it here rather than starting over.

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📝 Summary

Triads = two stacked 3rds. Major = major+minor 3rd. Minor = minor+major 3rd. Diminished = minor+minor 3rd. Augmented = major+major 3rd.

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