Saturday, December 26, 2009

12 days of musical terminology, day 2 - hemiola

This one comes up so often that I imagine most people must have worked out by now what it means, but I'll explain just in case there are some that haven't. A hemiola is a rhythmic device used in triple time (e.g. 3/4) in which 2 bars of 3 beats are effectively replaced by 3 lots of 2 beats (i.e. the accents are placed differently). It has the effect of making the music seem to hurry along a bit quicker. and therefore increases the excitement (for want of a better word) at a cadence.

It's used more in Baroque music than later, particularly dance movements such as minuets (although there ARE hemiolas in non-Baroque music - for example, there are even some in Gerontius). The Wikipedia article has a good example written out, but there are lots of very familiar ones in Messiah. Any movement in 3/4 time will have several. For example, in And the Glory of the Lord, the first one is at the end of the intro, just before the altos start. Bars 9 and 10 are still in 3/4, but the notes are actually three groups of two, and those bars would be performed with accents every two beats rather than every three. (In my copy all the hemiolas are actually marked with square brackets above and below the stave - not sure if this is the case in newer editions.) Sometimes conductors actually change their beat at a hemiola - i.e. they beat 2/4 instead of 3/4 - but in my experience this confuses too many people!

Other Messiah movements with hemiolas are "Thou art gone up on high", "Let us break their bonds" (not as obvious in this one, but they ARE there), "Thou shalt break them", "I know that my redeemer liveth", "The trumpet shall sound", and "If God be for us". You will be able to spot hemiolas in other works yourself - any Baroque piece in 3/4 will have some, plus many others. (There are also a few works in 6/8 that have hemiolas (i.e. there's a bar with three accents instead of two) but America from West Side Story is NOT one of them - it's in 6/8, and it does have alternating bars of two accents and three accents, but there are no proper hemiolas in the sense of "rhythmic device whose purpose is to lead to a cadence".)

1 comment:

KarlRKaiser said...

It's a stretch to say that "any baroque piece will have several hemiolas", and you wouldn't want somebody looking in frustration for one and not finding it.

They are typically used for novel effect at the end of a phrase, but if they were used regularly, it wouldn't be "novel".

The hemiola should have a clear succession of accents, beginning (here: *) that go: ONE two three, ONE two three, *ONE two ONE, two ONE two, ONE two three...

Often you will find an unexpected accent on the third beat of a measure, which might Start a hemiola, but that syncopation needs to be followed by another one two beats later.