Diminished and augmented triads by ear
Add the two tense triads to the familiar ones and tell all four apart.
Two tense triads
A diminished triad is a minor triad whose top note has dropped a semitone. It sounds tight and uneasy, as if waiting to resolve.
An augmented triad is a major triad whose top note has risen a semitone. It sounds unsettled and mysterious, as if hanging in the air.
A diminished triad on B3, resolving into C major
An augmented triad on C4: its top note pulls further up
Practice: Minor or diminished?
Practice: Major or augmented?
All four
Tell the triads apart with two questions. Bright or dark? (Major and augmented are bright; minor and diminished are dark.) Stable or tense? (Major and minor are stable; diminished and augmented are tense.)
Major, minor, diminished and augmented triads on C4
A diminished triad is easily taken for a minor one, an augmented for a major one: each pair differs only in the top note. Listen to whether the chord is at rest or asks to move.