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Deriving Keys from Chords in Music

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Re: Deriving Keys from Chords in Music

#31

Post by coldtea »

lc9er wrote: post #16
frogulis wrote: post #13

Earlier quoted context omitted.

Adam Neely released a pretty in-depth video recently with the opinion that Hey Joe is straight-forwardly in the key of E, as long as you don't get stuck trying to fit it into a diatonic, traditional Western framework. It's a good watch. https://www.youtube.com/watch?v=DVvmALPu5TU I had an unanswered question after the video -- are there listeners who don't feel that sense of "home" when arriving at the E chord? I cer…

I think context is important. If you are talking about guitar based music, then E is a pretty safe bet as home. But what if a group doesn’t use standard tuning? The first two examples that come to mind are Alice In Chains and Tool. They use E flat tuning and drop-d tuning, respectively (mostly). When I listen to them, Eb and D are home.

The instrument tuning doesn't change the fact that a song has a key/home.

If someone plays it in another key, transposes it etc, it will still have a specific key, just transposed.

In this case of course it's about the Jimi Hendrix recorded cover version, not trying to get some key that would hold across all possible versions.

Re: Deriving Keys from Chords in Music

#32

Post by declnz »

> A song could reasonably have a chord progression such as {Am, G, D, Am, G, Dm}, and the inclusion of both {D} and {Dm} would cause conflicts. Given that music theorists cannot agree on this stuff, there doesn't seem to be anything a computer can do that is better.

Whilst I'm no expert, I'm pretty sure we have hundreds of years of examples of borrowed chords [1] for music theorists to agree upon, so yes plenty of things a computer could do better (as per other comments).

[1] https://en.wikipedia.org/wiki/Borrowed_chord

Re: Deriving Keys from Chords in Music

#33

Post by olivierduval »

declnz wrote: post #32

> A song could reasonably have a chord progression such as {Am, G, D, Am, G, Dm}, and the inclusion of both {D} and {Dm} would cause conflicts. Given that music theorists cannot agree on this stuff, there doesn't seem to be anything a computer can do that is better. Whilst I'm no expert, I'm pretty sure we have hundreds of years of examples of borrowed chords [1] for music theorists to agree upon, so yes plenty of th…

Actually, music is a living art... so for example some blues chords progression would be "impossible" in classical music. And some "free jazz" or multimodal progression wouldn't work in blues

The point is: a computer is good to analyse something following a fixed set of rules, but not so good to analyse something that work by "breaking rules", like art. It's quite "easy" to write some program for classical music, or blues, or rock, or any specific music style... but it will hardly work for a different music style because the progression and interpretation of chords will be different

Re: Deriving Keys from Chords in Music

#34

Post by RHSman2 »

dkdbejwi383 wrote: post #30
lc9er wrote: post #16

Earlier quoted context omitted.

I think context is important. If you are talking about guitar based music, then E is a pretty safe bet as home. But what if a group doesn’t use standard tuning? The first two examples that come to mind are Alice In Chains and Tool. They use E flat tuning and drop-d tuning, respectively (mostly). When I listen to them, Eb and D are home.

Jimi played in Eb a lot too. Kurt Cobain and SRV too.

That’s cos it sounds heavier but the key is relative.

Re: Deriving Keys from Chords in Music

#35

Post by cvwright »

XCSme wrote: post #2

Is the first example with C and Am correct? It says the first chord of Am scale is A, shouldn't it be Am?

No, the first note of Am is definitely still A. What makes the difference between major or minor etc are the notes that come after.

For example, the A major scale goes A, B, C#, ..., while A minor uses the minor third, so you get A, B, C, ... etc.

Re: Deriving Keys from Chords in Music

#36

Post by jacquesm »

ksherlock wrote: post #12
acmj wrote: post #8

I am no musician. I heard quite a few musicians, with or without innate perfect pitch, can tell the keys in a chord, though maybe not to the 100% accuracy. For example, something like what the kid is doing in this video [1]. I am a bit surprised that this can't be done programmatically. [1] https://www.youtube.com/watch?v=vXivZlPu0ms&t=175s

Fast Fourier transform can be used to identify the pitches in a sounds sample. There are other methods but FFT gets the most press.

FFT is pretty bad at doing the lower pitches. Way too many notes will find their way into the same bin. And if you want more resolution you'll need an impractical FFT size.

Re: Deriving Keys from Chords in Music

#37

Post by XCSme »

cvwright wrote: post #35
XCSme wrote: post #2

Is the first example with C and Am correct? It says the first chord of Am scale is A, shouldn't it be Am?

No, the first note of Am is definitely still A. What makes the difference between major or minor etc are the notes that come after. For example, the A major scale goes A, B, C#, ..., while A minor uses the minor third, so you get A, B, C, ... etc.

The error in the article was fixed. I was referring to the first chord in the Am scale, not the first note. In the original article it said the first chord in Am is A, which was wrong.

Re: Deriving Keys from Chords in Music

#38

Post by acmj »

peterkos wrote: post #26
acmj wrote: post #11

Earlier quoted context omitted.

Thanks for the correction, but the key signature in a piece may be changing. Also, those with perfect pitch can tell the key signature from a short passage if there are few accidentals.

Well, that's the thing -- when listening to any song, even if you know the pitches, it is impossible to know if there are accidentals or not depending on the phrase. If a 10-bar phrase modulates in bars 2-5, and you listen to bars 2-5, you may conclude the piece is in key X when it's just a modulation from the overall key of Y. This also implies the piece follows western common practice, or is even tonal in the first…

The blog post criticizes existing software for their inaccuracy, but that is not their problem. The key signature of a particular passage may deviate from the overall key. I also wonder how they evaluate accuracy shown in [1] and what is the human accuracy in comparison.

[1] https://www.reddit.com/r/DJs/comments/hwlzyt/key_detection_c...

Re: Deriving Keys from Chords in Music

#39

Post by vkhn »

In college I built a project that could reasonably well predict the key of a given piece based on the distribution of note usage. For example, most pieces written in a major key would have the highest usage of the root, and the dominant of a key.

This obviously has a number flaws, but worked remarkably well for western music written between 1600 and 1900.

Re: Deriving Keys from Chords in Music

#40

Post by exabrial »

re wrote: post #25
exabrial wrote: post #14

Awesome. So what key is Revelation Song by Phillips Craig and Dean in?

It sounds like a I-v-bVII-IV progression in F# major. If you want to get modal, you could call it F# mixolydian.

Hilariously, that was subject to a debate amongst music theorists.
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