How to find the key of a tune: A brash and likely misinformed tutorial.
I’ve had some background in music theory, and I’ve seen some questions come up recently—both on the board and off—about what key a tune is. And, more specifically, about how this whole “mode” situation works. So I’ve taken a moment to sit down and compose something of an explanation, as I can. I’ve attempted to write this in such a way that a person need not read music (though you will need to be familiar with note names). I also tried to tailor it specifically toward Irish music, for simplicity’s sake. If anyone has any additions or corrections or refutations or donations, I’d be happy to accommodate and amend.
First of all, let’s cover the basics.
Most western music (which would include that of Ireland) employs a type of musical scale called a mode. I’m not going to go into the origins or meanings of the mode beyond what is required to find out which a tune employs. Wikipedia exists for those who are curious.
The most common mode is the Ionian mode. This is what most of us call a “major scale.” When you are playing in the key of D major (The Frost Is All Over, for instance), you are playing in D Ionian. If you made a list of all the notes contained in the D Ionian mode (in order), it would look like this:
D E F# G A B C#
All of the relative modes of D Ionian contain these same notes, they’re just in a different order. For instance, the order of notes in E Dorian is:
E F# G A B C# D
Notice that these notes are not only the same notes found in the D Ionian mode, but they’re in the same order. All that’s happened is the starting note has been shifted one over. What does this mean, you ask? Well, I’ll tell you.
Modes come in groups. There are seven modes in each group, one starting on each of the individual notes. All of the modes in this group share the same pool of notes, and therefore the same key signature (all tunes related to D Ionian have two sharps in the key signature). Here’s a table of all the relative modes of D Ionian:
Modes are generally classified as either a “major mode” or a “minor mode.” All this means is whether the overall feel of the mode is major or minor (or, for those of us in the know, whether the tonic chord is major or minor). Ionian is major, Dorian is minor, Phrygian is minor, Lydian is major, Mixolydian is major, Aeolian is minor, and Locrian is neither.
The modes you see most in Irish music are the Ionian, the Dorian, the Mixolydian, and the Aeolian. The Aeolian is also a natural minor scale.
“Now, Congratulations,” you say. “That still doesn’t tell me how to tell what mode a tune is in!” Well, let’s look at some tunes, then, shall we?
X: 1
T: Saint Anne’s
M: 4/4
L: 1/8
R: reel
K: Dmaj
|:fedf edcB|A2FA DAFA|B2GB EBGB|A2FA DAFA|
fedf edcB|A2FA DAFA|BGed cABc|eddc d2 de:|
|:f2fg fedc|Bggf g2gf|edcB ABce|baa^g abag|
f2fg fedc|Bggf g2gf|edcB ABcd|eddc d2 de:|
Now, the key signature of this tune is D Ionian, but is that the correct mode? As you recall, there are seven modes that share this key signature. Since the only difference between the modes is their root (that’s the main note, the one that is the “tonal center” of the mode), we need to figure out what the root of the tune is. For this, we’ll have to analyze the tune a little.
The first test is to look at the last note of the piece, because the vast majority of tunes end on their root. This tune ends on D, which makes me think that it is indeed in D Ionian.
The second test is to look at the last chord of the tune. Now, it takes some extra research to find the terminal chord, but I just so happen to know that it is, in fact, D major for this tune. This further confirms the fact that the tune is in D Ionian, because most tunes end with the root chord.
Let’s look at another tune:
X: 1
T: Connaughtman’s Rambles, The
M: 6/8
L: 1/8
R: jig
K: Dmaj
|:FAA dAA|BAA dAG|FAA dfe|dBB BAG|
FAA dAA|BAA def|gfe dfe|1dBB BAG:|2 dBB B3|
K:Bmin
|:fbb faf|fed ede|fbb faf|fed e3|
fbb faf|fed def|gfe dfe|1 dBB B3:|2 dBB BAG|
The key signature for this tune is, again, the same as one for D Ionian. Oddly, though, the final note is a B. This seems to imply that the tune is in B Aeolian (a minor mode), but because we have a discerning musical ear, we know that the tune sounds very major. So, we move on to our second test.
The last chord of the tune, according to my tune book is G, which is even more odd, because that would put the tune in G Lydian, a very uncommon mode for Irish music.
These two things together make me think there’s something odd going on with the end of this tune. Since most tunes also start on their root chord, let’s look at the first measure. The tune begins on a D major chord, which makes much more sense. Also, using that discerning musical ear again, I can feel that the end of the tune pulls a little toward D. In fact, I’d venture to say that one could, after the last measure, play a D major chord in the accompaniment, and not feel at all out of place.
Final verdict: It’s in D Ionian.
Let’s do one more, this time in a one-sharp key signature.
X: 1
T: Dusty Windowsills, The
M: 6/8
L: 1/8
R: jig
K: Gmaj
|:A2B cBA|eAB cBA|GAG FGG|EGG EFG|A2B cBA|e2d efg|
age dBG|ABA A3:|a3 age|dBd g3|gag gfe|dBA GAG|
EGG DGG|EFG ABc|Bee dBG|ABA A3:|A2A gAf|A2A gAf|
G2G eGd|G2G edB|A2A gAf|A2d efg|age dBG|ABA A3:|
Alright, the key signature for this tune is the same as G Ionian—one sharp. But, on the first listen, the tune sounds rather minor. So, we look at the last note of the tune, which is A. This makes me think it’s in A Dorian. The Dorian mode is minor, which is reassuring, and it’s also very common in Irish music, which is also reassuring.
The last chord of the tune is also Am, which pretty much cements the idea that this tune is in A Dorian.
Questions will be answered as ability allows.
