Musicianship
Rhythm - VII. Metric Modulation
1. Metric Modulation for Tempo
Metric Modulation is a scary-sounding phrase for a pretty normal, and even pretty cool phenomenon (see Life Tips Philosophy of Theory Tip No. 4 for more on “scary sounding phrases” in music theory!). This just indicates a tempo change where the new tempo is rhythmically related to the old tempo. You can change tempo with metronome marks such that a quarter note goes from 120 bpm to 60 bpm, and that’s fine and players and conductors will know exactly what to do with that. But in this particular instance, you can also use a metric modulation and just say the old half note equals the new quarter note. You will see this frequently in music as well, and the players and conductor will also know exactly what to do with that. The benefit of this is that players can relate the groove they should be feeling between the two sections, so they can determine the tempo by feel instead of cerebrally with math. With either way of indicating this, you’d still call it a metric modulation, because the new tempo is related in some direct rhythmic way to the old tempo, but if you can write it that way it will help the players. This particular example would be called half-time, and it’s a very common metric modulation, particularly in pop music and pop or rock-adjacent tracks.
My first example of this is from the bluegrass world. It’s a track on the latest album from Natalie MacMaster and her husband Donnell Leahy, called Canvas. The track has the excellent name “The Case of the Mysterious Squabbyquash”, which sounds right out of Lewis Carrolls’s poem “Jabberwocky”! This track is a blazing fast shuffle track, similar in some ways to Orange Blossom Special that we looked at in the Cross-Rhythm chapter. It uses the same 3-3-3-3-2-2 shuffle rhythm for a lot of the track (played very clearly), but the part I want to show here is in the middle where it goes into half-time for an electric guitar solo (by way of quarter note triplets). It then goes to double-time (in other words, back to the original tempo) for the rest of the track after this guitar solo. I’ll play the track from the beginning, as it’s got such a great groove and it’s worth listening to all of it for rhythm, and then at 1:38 in the video they hit the half-time part, and at 2:05 they go back to the original tempo:
The next track I’m going to feature is from William Pint & Felicia Dale, another sea shanty, or at least a song with a sea theme (we saw one from them also in the 3-3-3-3-2-2 cross-rhythm section). This is “Issac Lewis” from Pint & Dale’s album Midnight on the Sea. This one has an example of a type of double-time metric modulation that comes up a lot. There’s a slow introduction to the song for the first several seconds, and then the real groove starts with the second verse in this case. I could have picked about half a dozen tracks off the top of my head that do this (here’s one from The Barra Macneils with a similar effect, and I’ve even done this in my music before - see “The Dark Journey” and “Overture for the Planet Earth” on my Orchestral Concert Music playlist on my Music page if you’re interested). This one gives me a chance to mention a couple of other points that we looked at in earlier sections, and I just like this track a lot. It also points at another feature of a lot of folk music in particular, which is that the track is really high energy and upbeat, but the story it tells is not a happy story - though the liner notes for the album relate that it is based on a true story(!).
This track is a great example of a 3-3-2 cross-rhythm groove once the real groove enters (at 0:24). It also features rubato in the first slow section. They are taking some time between vocal phrases compared to strict metronomic time. Then the beat doubles when the 3-3-2 groove enters, and when the hi-hats come in on the third verse, they are playing constant (3-3-2) 16th notes at the new doubled tempo, so we actually have what would have felt like 32nd note subdivisions compared to the first tempo at the opening. All this time, the vocal melody still has the same tempo it had originally (just steady instead of rubato), so this is one of the main things that gives this track the really intense energy that it has.
This track is also a good example of how to develop a track over a long period of time - it’s nearly 8 minutes long, which is a long time for any song to maintain its interest. As I mentioned with the Barra MacNeils’ “Living The Dream” (See Section 2.9), part of this comes from the words changing with each verse - it wouldn’t work nearly as well in a purely instrumental form (that’s what modulation and changing melodies are for!), but they do other things as well. They bring in elements slowly over time, the texture and range of the instrumental backing expands over time and the groove changes (they drop the 3-3-2 rhythm in some of the choruses as they go through the song - cross-rhythm is a really cool tool, but especially in a track with this relentless of energy, it can be wearing over too long a time. Letting the groove go back to straight 4, even just for a few bars at a time in the choruses, really helps keep the song managable).
The final example I’ll pull for this section actually is one of my tracks. I’ve mostly been avoiding examples from my tracks for this guide, but this is my favorite track of a recent project I did for the music library I work for, KQM Production Music. I wrote an album (an EP right now) of epic orchestral Christmas music for the library. This is the final track on the EP, a dramatic action medley of “O Come O Come Emmanuel” and “God Rest Ye Merry Gentlemen”. I flip between them twice each, and each time I metrically modulate between meters to rachet up the tempo and the energy. You’ll also notice a 3-3-2-2 5/4 cross rhythm the first time you hear “God Rest Ye Merry Gentlemen”. The track ends with a fast 4 with the tune in the violins and upper winds, syncopated accents in most of the other instruments, and epic toms booming away behind them.
2. Metric Modulation for Meter
As a notation convention, you will also see metric modulation frequently when you change from a simple to a compound meter - players need to know whether the beat or the subdivision is constant across the change, so going from 2/4 to 6/8 (simple duple to compound duple), you need to indicate whether the 8th note is constant, in which case the beat slows down, or whether the beat stays constant but now simply has three subdivisions instead of two (or four if there were 16th notes before), which would cause the 8th note division to speed up while keeping the beat the same.
Here’s an example of a track that keeps the subdivision constant, such that the beat changes. This is the last track from Ben The Hoose’s album “The Little Cascade”, Barren Rocks. We saw the first track back in the 3-3-2 section of Cross Rhythms. This one starts with a reel in 2/2, playing 8th notes (subdividing the beat into 4 subdivisions). At 1:44, they switch instantaneously to a jig rhythm (6/8), keeping the 8th note constant so that the beat gets faster in a 4:3 relationship. There’s no preparation in this track, they just jump to the new feel between one note and the next.