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Home > Advice / Theory > Key by Ear

How to Determine the Key of a Song by Ear

Key is an often misunderstood musical function. But knowing the key of a song has huge benefits, especially for jamming, improvisation and writing new parts to a song.
focus on key
By the end of this ear training focused series (no charts!), you'll be much clearer on what key is, how to identify and get into key quickly and how to use it to your benefit as a musician.

Let's start by answering the obvious question...

What is key?

A lot of music (including most classical and popular music) has a chord or note which can be considered "home" or the central point of the song. This is often called key center or just key.

When we talk about a song being "in the key of C major", what we really mean is "C major is home".

This home chord is called the tonic or 1 chord (numeral I for a major tonic or i for a minor tonic). Whatever the tonic is (C major, C minor, D major, D minor etc.), that is our key (and vice versa).

So in any numerically written progression (e.g. 1 4 5, 2 5 1, 1 3 6 4), 1 always represents our tonic and key. The other numbers/chords aren't so important right now.

For example, in the key of A major, our 1 chord would be... A major. If you're playing lead, you could start by trying A major pentatonic.

In the key of E minor, our 1 chord would be... E minor. Again, for lead playing, start with E minor pentatonic.

The other chords in a progression can be seen as the "journey away from home". Some songs use short journeys (i.e. one or two chords), others venture far from home and maybe even head to a new home (key change).

Often, especially in pop and rock, the tonic chord is the first chord in the song. So there's a strong clue of the key of the song. But this isn't always reliable as sometimes the song will start "away from home". We'll cover these complications later.

Finding and naming the tonic

Grab your guitar and try to find the root of the chords in the audio track below as quick as you can. Simply use the low E string and play from the open E note up the frets, one by one, until you're confident the note matches the root of the chord being played. Each chord plays for around 15 seconds.

As long as you know the notes on the fretboard, you'll be able to identify the note you're playing. This is the root of your key.

small chevron Click to hear (right click and "save as" to download)

The more you practice matching notes by ear like this, the more you develop the pitch recognition part of your brain. You'll be able to find notes/chords quicker and quicker.

Try pausing the track and see if you can hold that chord in your head. Hum it to keep it going and then find it on your guitar.

Once you can get the root, try to determine if the chord is major or minor (answers below). Again, it'll just take time to be able to distinguish between major and minor by ear. Usually, you'll go some way to picking this up when learning your first chords (for example, the difference between E major and E minor). Refocus on this distinction if you're still unsure.

Answers:  chord 1 = A major   chord 2 = E minor   chord 3 = C minor   chord 4 = F# major   chord 5 = D minor

Be aware though that not all songs start on the tonic chord. Sometimes a song will start "away from home". The tonic chord will still be there, but it might be the 2nd, 3rd or 4th chord in the sequence. We'll come to this later.

Learn How To instantly identify the chords in any given key...
I highly recommend Jonathan Boettcher's crash course in guitar theory.

Tension and resolution

As we approach the tonic there are often musical signposts, called cadences or hooks, that tell us we're about to return home. This is usually supported by some kind of musical tension that is then resolved as we return to the tonic.

For a chord to have this tonic quality, and therefore establish the key, there needs to be resolution - a feeling that, if we finished on that chord, there'd be a sense of arrival, rest or completion.

Tension is often used to facilitate this resolution.

Listen to how resolution is used in these examples...

small chevron Major Key   small chevron Minor Key

In those examples there were chords leading up to the tonic in several keys. Hopefully you could hear that sense of arrival when the resolution occurred. This is one of our "key clues"!

Now take a listen to this famous Queen song, Somebody to Love. Skip to 0:48 where Freddie sings the line "can anybody find me... somebody to love". On that word "love" we feel like we've arrived home. The chord preceding it (the V chord, incidentally) was loaded with tension that supported the resolution...

Fast forward to 3:39 and you'll hear this tension chord being held for longer. But again, we resolve eventually.

This resolution also helps us to identify the tonic chord and therefore confirm the key (using the chord matching method from earlier). Listen out for it in songs you know.

Tension > resolution is arguably the most important function in tonal (western, popular) music. Even artists who have shunned music theory and the "pop status quo" have still managed to write songs that gravitate towards a key in this way.

Why? Well, without wanting to get too bogged down in the science, simply because it makes us feel good.

That's not to say songs don't occasionally leave us hanging, but...

...that very feeling of unresolve reaffirms the integral role key plays in connecting music to our nervous system. Whether or not the resolution is there, we anticipate it. We feel it. It's almost as if this tension-resolution dynamic is in our DNA.

Key is nothing more than a center of musical gravity - a point of resolution in a sequence. That's what we call a key center.

In a chord progression, a key center can either be major or minor. A happy home or an unhappy home! Take a listen to this sequence resolving alternately to C minor and major (known as parallel keys)...

small chevron Click to hear

When using power chords, which are neither major or minor, key is still determined by resolution. For example, take a listen to this riff in G...

small chevron Click to hear

In a lot of metal, the tonic note will be the open 6th string (E, D, C, B, A, depending on the tuning).

Once you can identify the tonic chord, based on this resolution feel, it's again just a case of finding the root and quality (major/minor) of that chord on the fretboard. This will tell you the song's key.

But why do guitarists need to know about key?

You don't need to know about it, especially if you only intend to learn songs note for note or write your own music as a solo artist.

But if you're planning on developing your improvisation skills, collaborating in some way with other musicians (e.g. jamming with a band), then key is the quickest way of communicating which notes can be used without wandering into unpleasant dissonance and clashing with what others are playing.

It helps you find your bearings, a "starting point" on the fretboard.

It tells you what scale(s) will sound good in a solo.

It will also help you with transcribing music by ear. Once you can pick out the key, the other chords will often fall into place, or it will at least be a lot easier to find them through trial and error.

It's a time saver in other words. You'll rely less on trial and error.

Plus, when someone plays or sings out of key, you know about it! You know something is not quite right.

Think of key as a guide in that respect. By knowing the key, you'll know where to position your scales (e.g. if the key is C major, a natural choice would be the C major scale or C major pentatonic), related chords/harmony, and everything will fall into place much more effortlessly.

In the next part (coming soon), we'll delve deeper into how key works and how knowing the key can help you as a musician. For a deeper understanding of how key relates to other aspects of music theory (so you can tie it all together), I highly recommend Jonathan Boettcher's crash course in guitar theory.

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