Demystifying The Songs: Simple Music Theory Explains So Much

As an elementary school student, I took three years of piano lessons. Every Wednesday, I’d trudge up the hill to kindly Mrs. Clancy’s place on Fourth St. to sit with her on the piano bench for 45 minutes. It was my mom’s idea, not mine. I learned how to read music and play the notes I was reading. It didn't feel all that musical—more like an interesting version of typing.

One day, while practicing, I smashed a bunch of piano keys out of frustration for being inside and having to practice. My mother told me to go outside and play.

That was the end of the trips up the hill to Mrs. Clancy’s house. I had little interest in music at that age—listening to it or playing it. And a teacher can't give a student such a gift. I wanted to be playing basketball, baseball, and football.

In the eighth grade, I did get the music bug, and began collecting rock albums. It became an important part of my life, but I had no idea how to learn these songs on piano, and nobody was around to teach me. I continued to leave the instrument alone. Mrs. Clancy didn't teach me about chords because classical music sheet music doesn't list them. Instead, it lists every single note to play, which I found uninspiring.

There were contemporary songbooks around the house that listed a song’s chords. I didn't know it at the time, but it's a breeze on the piano to decode every chord—it’s all about the spacing between a chord’s three basic notes.

The college years were full of music, both recorded and live shows, but I didn't pick up another musical instrument until I was 27, when I bought an Alvarez acoustic and practiced like crazy. The guitar came much more naturally to me than the piano. I was playing songs I chose. The song books I used had all the chords for the songs, and a copy of The Guitar Handbook showed how to play every chord in several positions. That book was my teacher. I just had to grind away to get to the point where my fingers (sore and reddened for weeks) would go, effortlessly, where I wanted them to go. Once muscle memory clicked in, playing became fun.

I only learned the basics of music theory as a guitar player, but that was a major breakthrough. I'd always heard about people who can play music “by ear.” I was in awe. I needed sheet music in front of me to play anything.

It's not that mysterious. To play a song by ear, the first thing to do is figure out what key it's in. If a song ends on a G major chord, it’s probably in the key of G major, etc. Bass notes are another thing to look at.

Let's use the Beatles song “Let It Be” as an example. The resolution in the final chord of the song is clear to the ear. There's no tension left. I don't have perfect pitch, so to identify that “home” chord, I’d play some notes on guitar or piano until I get the sound of that chord, which in this song is C note. Playing a C major chord and comparing it to the final chord I hear on the song tells me it's the same chord. So “Let It Be” is in the key of C major.

Then I'd consult the music theory known as the “circle of fifths” chart, which tells me which chords will fit into songs in every key. The C chord is at the top of the chart. To its left is F, and to its right is G. If I try to play the song using just  C, F, and G, it works pretty well, but it becomes obvious I need one more chord.

Directly below the C, F, and G chords on the chart, I find D minor, A minor, and E minor. I find that A minor is the missing chord. So I’ve just figured out that I need C, F, G, and A minor to play this song “by ear,” using no sheet music. Adding the two other minor chords I didn't use for the song—D minor and E minor—to these four chords gives me the six chords I'd need to play just about any popular song in the key of C.

The circle of fifths gives one access to the harmonic DNA of Western pop music from the 1950s to now. It can be used to figure out how to play thousands of songs, unless they’re written by someone on the level of Brian Wilson of the Beach Boys in his Pet Sounds era.

There's so many pop songs that are even easier to figure out than “Let It Be.” Thousands of them use only the I, IV, and V chords that define almost every blues song when they're used in a particular order that’s called the I-IV-V progression. The Roman numerals refer to the chords built from the first, fourth and fifth notes of the scale. In the key of C major—the scale is C, D, E, F, G, A, B—these chords would be C,F, and G.

Outside of the straight blues, such songs as “Johnny B. Goode, "Twist and Shout," "La Bamba," "Wild Thing” and “Hound Dog” use only these three chords. On the country side, there's “Your Cheating Heart", "Folsom Prison Blues" and so many more. No sheet music’s needed to learn these songs.

Most devoted fans are unaware of the simple underlying chord structure of songs they've listened to so many times. Instead, they feel what they can't articulate, which is what songwriters want. Intuitively, listeners are often able to predict the sound of the next chord, especially when there's a resolution from V to I. A dramatic example is the Ronettes’ “Be My Baby.” When it resolves on the E major chord (I), it's a strong harmonic closure that feels both inevitable and emotionally rewarding. Brian Wilson, famously obsessed with the record, described that chord landing as one of the most spine-tingling, goosebump-inducing moments in all of pop music.

It's not necessary to know a lick of music theory to enjoy playing an instrument, or to play it well. But it does open up doors. I watch several music theory YouTube videos per day, hoping I can open up a few more of those doors.