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The easy guide to music theory: augmented and diminished chords explained

Augmented and diminished chords have something of a bad reputation. Whenever anyone makes a joke about an overly complicated piece of music, they’re usually part of the punchline.

In actual fact, though, they aren’t really that difficult to get your head around and don’t really warrant the scary mystique that seems to surround them. They’re just slightly altered forms of regular major triad chords.

In musical terms, augmented means the same as ‘stretched out’, while diminished can be thought of as ‘squeezed’. An augmented chord comprises notes that are spaced apart at wider intervals than those of a regular triad, while a diminished chord is so called because it features narrower intervals than the standard version, making it more compact.

Augmented chords have the unique distinction of not appearing when a major scale is harmonised. This means that when you stack alternate notes from a major scale on top of each other to form triads, you end up with major triads (C, F, G in the case of C major), minor triads (Dm, Em, Am) and even a diminished triad (Bdim), but never an augmented triad.

Diminished chords are a favourite of horror movie score writers thanks to their somewhat spooky, foreboding sound, and very effective for use in transitions, as well as for creating anticipation or a feeling of tension. They also often turn up when songwriters want to shift to from one key to another.

Here, we aim to strip away some of the mystery surrounding these chord types and show some practical examples of their potential usage.