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What is the method to figure out the key to someone else's song?

Let's assume you've never played the song on an instrument and it's not your own song.

Is it faster to try to figure out chords and then guess and surmise the key, or perhaps a similar method but with a basic scale or figuring out the melody by ear?

(So far it seems to me that the fastest non-instrument way is to Google the song's sheet music but this question is about using your ear and instrument to find the key.)

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    Do not trust google to give you the real key in sheet music, there is a very good chance what you will find is in an easier key than the actual performance. – Legorhin Oct 23 at 18:25
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    @AlbrechtHügli - sing along = know the key? I have to disagree, unless one has absolute pitch ! – Tim Oct 23 at 21:12
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    @AlbrechtHügli - Awkwardly, there are prominent counterexamples where the first 2-4 measures don't sound like they're in the same key as (at least the majority of) the rest of the piece. One such example is Chopin's Ballade No. 1 in G Minor, which starts by elaborating on an A flat major chord. – Dekkadeci Oct 23 at 23:44
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    Taking @Legorhin's point. There may well be more than one recording, in different keys to suit the vocals. There are many transcriptions that are put into somplified keys, often for beginners. Elvis recorded early songs in lower keys than the originals. What would be the 'correct key'? – Tim Oct 24 at 9:46
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    The published sheet music definitely CAN'T be trusted. Neither the key or the arrangement. Both are very often 'simplified'. – Laurence Payne Oct 24 at 14:13
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Do you find it faster to try to figure out chords and then guess and surmise the key? ... or perhaps a similar method but with a basic scale or figuring out the melody by ear.

I would personally go with none of the above!

The "key" of a song (or composition, etc.) is just another word for the "tonic" of the piece. And by tonic, we mean the most stable pitch: the pitch to which all other tension points and resolves. The common metaphors here are that tonic is "home base," and that it's the sun around which all other pitches (the planets) revolve and to which they are all gravitationally attracted.

As such, if you're looking for the key of a piece, find the pitch that sounds the most stable. This will be the tonic pitch.

If you want to get more specific than that (say, C major or C dorian), then you'll need to go the next step of taking a pitch inventory and seeing what scale collection it creates.

But honestly, so much music you hear these days doesn't stick to a single scale; in many (most?) cases, you're better off finding tonic and not trying to extend your key categorization any further than that.

  • Perfect. So why not just decide right off the bat if F or F# is one of those stable pitches? If F then Bb. If Bb then Eb, etc. If F# then C# too? When I do this on bass it takes ten seconds to be close to key. Then it's just deciding if there are additional accidentals. For example. Deacon Blues ... F# fit and so did every other note that were fifths up from it... the 11th fret of my bass moving upward. So I surmised it's either 4 or 5 sharps... sheet music said 5, Bmajor. – Randy Zeitman Oct 23 at 23:07
  • Isn't finding whether a piece is in a major or minor key a worthy goal? – Dekkadeci Oct 23 at 23:46
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    @Dekkadeci It is! But once you find the tonic, finding the "main" quality (major vs minor) is relatively trivial, even without much experience or knowledge. – Lyd Oct 24 at 4:43
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    @AndrewT. I thought "none of the above" was referring to the propositions in the question – theonlygusti Oct 24 at 10:05
  • @Dekkadeci Also, so much music is in a mix between major and minor. You can be in C major and still use E-flat and B-flat chords all the time. – Richard Oct 24 at 10:41
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By ear

This is an ear training approach that many music programs use: try to sing the tonic note of whatever chord progression you are listening to. You start by singing the tonic of chords, then move to sing the tonic of a progression, to eventually sing the tonic of a song. That's your key. By doing this you are trying to find the pitch that sounds more stable, using only your ear.

It's much easier if you have some ear training background though. Stuff like identifying intervals and simple chords.

Using this idea, and your instrument, without the ear training part (you'd be training your ear, just not as much), you can try to find the bass notes of the chord progressions, or a bass note that kind of works through all the progression.

By harmony

Another way, where you need to be somewhat familiar with harmony, and know some of the chords of the song, is by looking at the quality of the chords involved. C mayor scale, for example, builds the chords C major, D minor, E minor, F major, G major, A minor, and B diminished. if you have a F major - G major - C major progression, you are probably in C major.

That's with triads, but with dominants it can be even more explicit. Search for dominant 7 chords and other chords that play that function (like diminished 7 chords), those often resolve to the tonic. There's secondary dominant chords that do not resolve to the tonic though, but they normally resolve to something important like the dominant or subdominant.

Most of the time you can get away with paying attention only to the cadences (V I, IV I, II V I, etc), since they normally paint a pretty good picture of the tonality.

By scales and melody

Sometimes when learning new songs, I try to play some important parts of the melody on my guitar, and then improvise a little over that idea. At that point the key becomes apparent most of the time, since the key is based on scales. If you can play F G A Bb C D E (doesn't need to be that order) and it sounds cool, you are probably in F major or D minor or any of the parallel keys.


For the three approaches, remember that harmony can get tricky. For the minors we have common variations like harmonic, melodic, and dorian. So it's very common that the 6ths and 7ths are "displaced", along with some of the harmony. There's also key modulation, and music that lacks tonality and key!

But for the less exotic songs, which are the huge majority, you can keep it simple.

3

Disagree with the first two concepts, agree with Richard's.

The tonic note is literally key to it all. Find that, and you usually have the scale used and the chords available. may be major, may be minor, but that's not a big deal to work out.

The tonic is the 'home' note, and thence the home chord. It's the one where in a piece, things could stop at that point. It's usually the chord that occurs most often, and the one the piece gravitates to at the end. Out of the 3 main chords in a major piece, there's I, IV and V. Since IV and V are so close together - a tone apart, it's not too bad to hear when they're played one after the other. IV>I seems to go down, and V>I seems to go up. Playing them in all different keys will get the ears more used to how they sound following each other.

Playing in the house band at open mics, this works well, and the key's found within 3 or 4 bars, normally. Useful when someone can't tell you beforehand, or even sometimes tells you a key that it really isn't.

For me, listening to the bass usually reveals it best. I'm listening out for notes 1, 4 and 5. If 1 and 5 occur in the same bar, it feels very stable, so I'm listening for when it comes again. It'll often be at the end of a verse, and the end of a middle eight will be a V chord, most likely to start a new verse on the I. Ha, found it again!

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    Which "the first two concepts" are you referring to? – Andrew T. Oct 24 at 8:47
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    @Andrew T - I don't agree with the answers provided by Lyd and Viking Children. – Tim Oct 24 at 9:50
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I play guitar and generally start with ear and instinct. It gets a lot easier when my conscious mind knows what key signature I'm in. In order to confirm to my conscious mind, I look for the semitone intervals that match the song. For example, if the notes B and C both sound right to me, then it's either a mode of C major (with C as the tonic) or a mode of G major (with C as the fourth.)

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I just figure out the scale, and from there you're going to be able to ballpark what key you're in. A key can use different scales, but the tonic note is what gives the key away. If it's an A major scale chances are you're playing in A. It gets mroe complicated in classical or jazz, but for your rock/pop/folk/country/blues music this works more often than not.

Here's a question with a more in depth answer

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The way I do it, as the song plays, I just play random notes on my instrument. It's very apparent which notes are not in the key as they will sound like a train wreck when you play them along with the song. So I quickly know what notes to avoid, the notes that mostly sound like they "fit" will be the seven notes in the key.

The note that they all tend to resolve, especially at the end of a phrase, and definitely at the end of the song, will be the tonic of the key. So you can just fast-forward the song to the end and pay attention to the last note of the melody. For example, in this song from Wizard of Oz, If I Only Had a Brain, if you fast-forward to the end of it you'll see that the last note when Scarecrow says "Brain" at 3:44 is a D, so the key is in D. And it's a D major scale, with the notes D, E, F♯, G, A, B, and C♯. If you try any other notes you'll notice they don't fit if you play them as the song is playing.

Also note that on a piano, when you find the black/white notes that "fit", just based on their visual pattern you'll know the scale, assuming you've practiced scales. The more you do this the faster you get at it. Just try this on any random song you listen to.

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    Pieces that switch keys by the end are somewhat commonplace. The semitone or whole tone shift upwards is so common in pop music that it's called the "truck driver's gear change". Classical music often switches from a minor key to its tonic major by the end, and marches often shift to the subdominant key and stay there. Less traditional genres like heavy metal may jump between practically unrelated keys and stay on a previously jumped-to one at the end. Don't always trust that the last note of the melody is the tonic. – Dekkadeci Oct 24 at 10:32
  • @Dekkadeci the vast majority of songs remain in the same key. – foreyez Oct 24 at 12:23
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    I have my doubts when I can name so many examples of pop and rock music alone that change keys by the end (Celine Dion's "That's the Way It Is" and "My Heart Will Go On", Bon Jovi's "Livin' On a Prayer", the Kermit song "Rainbow Connection"). In other genres, for example, it's harder to name a John Philip Sousa march that doesn't change keys by the end. – Dekkadeci Oct 24 at 12:41
  • @Dekkadeci lol want me to list out the songs that remain in the same key? you're describing exceptions, not the rule. you're saying the amount of songs that change keys are the same amount that remain in the same key? not even close. – foreyez Oct 24 at 13:15
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    I'm saying that the ratio of pieces that end in the same key they start in to pieces that do not end in the same key they start in is probably much closer to 50:50 than you think it is. Though this figure is probably skewed high by video game music and its need to loop, I'd say that a ratio of 90:10 among all published music is too high. – Dekkadeci Oct 24 at 17:56
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It's obvious to me that there are several different methods for determining the key of a song. I use the method described by Richard and I find the key almost immediately most of the time, but just like everything else in music, I had to work at it in the beginning, I had to learn how to hear it. I don't think that one size fits all with this technique and it's up to the individual to find the method that works best for themselves. Also, I'm not absolutely certain any method is completely fool proof every time.

  • My annex to Richard's method has worked 90% for pop music. – Randy Zeitman Oct 25 at 19:26
  • @Randy Zeitman- Sounds like you may have found your method, run with it. – skinny peacock Oct 26 at 14:19

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