How To Find The Key By Just Listening

Everything balances on I
Everything balances on the I chord

It happened again.

We were in rehearsal for our Sunday services, and our final song needed an intro. The chords on the chart correctly read: C G Em D, and I heard someone exclaim, “this is the one in C, right?”

Uh-oh, I thought. We may have a problem.

The song is in G. But they didn’t know that.

Now our songs often do start on the I chord, that is, the chord with the same name as the key. It’s built from the 1st, or the root, of the major scale. But songs don’t have to start there. The key center might be anywhere in the pattern.

And knowing what key the song is in is pretty important for our music team members to know.

Determining the Key

So how can you tell what key a song is in? If you can’t read music and you don’t know what a key signature is (and the key signature is a signpost, not a reason or a definition, by the way), what should you do? How can you just listen to a song and figure it out?

Well, the short answer is, you just have to know what to listen for. And it will take some practice. But you can learn to do it!

Here’s how it works.

The Key Center

Every song in our culture revolves around a key center. Well, most songs. There are some pieces of music that are atonal, meaning they don’t follow quite the same harmonic rules as just about all the rest. Let me pull a number out of the air: I would guess these make up less than 1% of the music we hear.

Right now I’m not talking about atonal music, but rather the everyday kind of music you’ll encounter everywhere you go: songs you’ll hear on the radio, TV commercials and themes, symphonic pieces, blues, jazz, top 40, country. Each song has a very specific harmonic structure, and the structure is based around the key center.

The key center is the chord that brings everything into balance. The melody and all the other chords are to varying degrees removed from this chord. They will each sound like something else needs to happen next, like they are waiting for something.  But the key center is the fulcrum, the nucleus that everything else revolves around.  It is, as I mentioned, the chord built from the 1st of the major scale, so we’ll call it the I chord (roman numerals mean chords, not single tones).

The Only Chord That Makes The Song Sound Finished

You’ll hear the I chord as being the only chord you could potentially end the song on and have it sound finished and complete. Try it with some of the recordings you own. Start playing a song, then when you think you’ve found the I chord, hit pause. Does the song sound like it should end on that chord? Try it again and again until you’re pretty sure you’ve found it.

balancing scaled 1This works for songs in major keys and minor keys, fast songs and slow songs, rock songs, country songs, polkas and reggae. Even rap for the most part. There will be a chord that everything seems to revolve around, the other chords moving out from it then back toward it. But when you play that chord, the I chord, things come into stable repose.

The placement of the chords within the rhythmic framework of the song will also affect your perception of the key center, though not the actual function of it. For example, the downbeat of a song is naturally the strongest point in time as you play any progression. You very easily, almost automatically, want that spot to be filled by the I chord. So when the song for my team didn’t start on I, it was a confusing moment for one of the team members.

Okay, I guess we’ve got some theory to cover in our next rehearsal!

So the song might start on the I chord, or it might not. The composer may choose to end the song on the I chord, or she may not. But the fact that the I chord is the key center does not rely on its position in the song. It gains its strength from its position in the scale.

There are mechanical reasons for this, of course. We’ll cover the mechanics in another post soon. For now, let’s just say that the I chord is simply the only chord you can end the song on and have it sound finished. Try the exercise above, then let me know how you did!

Can you pick out the I chord when you’re listening to your favorite songs or artists, or even when you hear the Muzak at the mall?

Please leave your comment below, or email any questions about music, musicianship and practical music theory to me at [email protected].

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© 2014 Steve Case