Tuesday, October 20, 2009

Phrases and cadences

Last week we talked about phrases. A phrase is a short, meaningful unit of music. Symbolically, it's the expression of a single breath. In rock songs, phrases are most often 4 or 8 bars long, although other lengths of phrases are common.

In traditional music theory, a cadence is a musical gesture that marks the end of a phrase. You might think of a cadence as musical punctuation; it helps you understand that the phrase is over.

A cadence is a ritualized sequence of chords. Music theory describes four basic types of cadences:
  • [five] [one] — in C major, G C — a full cadence or authentic cadence
  • [one] [five] — C G — a half cadence (and, really, it could be almost any chord leading to [five])
  • [four] [one] — F C — a plagal cadence (they really didn't respect [four] chords in olden days — even tried to implicate them with the plague)
  • [five] [six]m — G Am — a deceptive cadence
In traditional European music, every phrase had to end with one of these four chord sequences (or some close variation of them). It was practically a law. You could get your composing license revoked if you didn't obey. If that sounds absurd and arbitrary and incredibly limiting, well... it was! But remember:
  • Traditional music was based on melody, not chords. Great melodic inventiveness more than made up for simple, formulaic chord structures.
  • 19th-century composers changed keys very freely as a way of getting some other chords into the music.
Still, by the beginning of the 20th century, composers rebelled, threw off the yoke of these arbitrary rules, and started creating much more richly varied music. And the only reason we still study these antiquated and arbitrary formulas today is... what? Just the fact that most rock songs still follow these rules most of the time.

So if you're putting chords together and feel like you don't know what you're doing, you can always fall back on these four traditional cadences. If you end every phrase with one of them, or some close variation, you can be confident that your chords will make musical sense to the audience.

Tuesday is Beastly Fundamentals Day.

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