Diary of an OCW Music Student, Week 4: Circular Pitch Systems and the Triad

Education Insider talks a lot about OpenCourseWare (OCW), so we decided to put some to the test. Therefore, over ten weeks this fall we'll be taking a course from the University of California - Irvine ourselves. Here, a semi-professional musician sees what he can learn from an OCW lesson in circular pitch systems.

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By Eric Garneau


It's as Easy as 1, 4, 5

In lecturer John Crooks' shortest lesson yet (only eight minutes long!), we explore the concept of triads, three-note chords composed of a root note plus that note's third and fifth tones. We're also introduced to I-IV-V chord progressions (also known as tonic-subdominant-dominant progressions) that are common ways to reinforce a root tonality, as well as common progressions out of which lots and lots of songs have been built.

All of this discussion takes place using our helpful friend from last week's lesson , the circle of fifths. Again, I can't stress enough how useful (and simple!) a tool this is for any musician. Last week we illustrated that the circle of fifths can be used to easily find relative minor keys and to help harmonica players figure out how to play cross-harp on a song. This week we've got an even more primary use for it that any budding songwriters should find invaluable - it's a chord finder!

Okay, not really. I mean, that's not what the circle's for, necessarily. But you can totally use it for that anyway. Let's take a look at this circle again. Given what we learned from Crooks' lesson this week, we know that the major triads of the two tones adjacent to our primary tone on the circle form a I-IV-V relationship (if you're looking at it from left to right, it's IV-I-V). Let's put that in simpler terms: look at C, sitting at the top of the circle. If you've got a song in the key of C major, the circle of fifths and Crooks have made it simple to understand some other chords that will likely go in your song: C's neighbors the dominant (G) and the sub-dominant (F), because those chords reinforce the tonic chord, our original C. It turns out that these relationships are found all the way around the circle which, as we saw last week, is based purely on mathematical relationships.

circle of fifths

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Applied Mathematics

If you think about it, there are an awful lot of songs - in popular music especially - that are based solely on the I-IV-V tonal relationship. One example I like to cite is Bob Dylan's 'Knockin' on Heaven's Door,' famously covered by tons of artists (like Eric Clapton and Guns N Roses to name a few). This song's in the key of G. If we use the knowledge we gained from today's lesson, we can understand why basically the only other chords you need to know to play that song are a D and a C (if you want to get fancy there's an Am7 in there, but we can ignore that for now). And that's just one example of a 3-chord song based on this ultra-simple structure discussed by Crooks. If Dylan can get away with it - if the Axl Rose of 1991 thinks it's cool - then why can't you? Mathematics and the circle of fifths can therefore help us with our songwriting endeavors, even if we only start with the basics.

At the end of his lesson, Crooks states that the I-IV-V progression is the 'crux of the tonal system,' and a cursory glance through the pop/rock songs of the last half-century would confirm that handily. With this understanding of simple harmonious relationships in place, musicians have been given the tools to understand why there are so many songs like that out there, as well as how to construct them themselves. And now that we can speak in the language of tonics, dominants and subdominants, we're in a position to move forward to Crooks' next lesson, in which we're going to build a major scale, so come back next week and check it out!

Is all this technical knowledge not your cup of tea? Check out these music classes for non-musicians!

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