The music theory behind modal and tonal harmony

In the first of a two-part instalment, Dave compares and contrasts two different approaches to harmony

When discussing traditional Western music theory, we use the term ‘harmony’ to describe how a melody works with the chords that accompany it. For the most part in this Easy Guide series up to this point, we’ve been exploring what’s known as ‘tonal’ harmony – the kind of thing relied on heavily by composers from 1700-1900 or thereabouts, and from which the vast majority of modern pop music is derived. We’ve been talking about chord progressions that move in a particular direction, are based mainly on three-note chords or triads, and have a general tendency to gravitate towards the tonal centre or ‘tonic’ chord. There’s another type of harmony, however, that can also be used to great effect, and that’s ‘modal’ harmony.

The type of modal harmony I’m talking about here is the kind that’s a favourite of modern jazz composers, rather than the kind you’ll come across in the discussion of medieval Gregorian modes – fascinating though it is, this kind of thing is of limited appeal to computer musicians!

So over the next couple of issues, I’ll turn the spotlight on each type of harmony and highlight the differences between the two, with some practical illustrations of how to make each idea work for you in your productions. We’ll start this month with a look at what makes tonal harmony tick, finishing up next month with an in-depth look at the basics of modal harmony.