enter image description here

Given the scale Lydian in the key of C we can determine that the F# (rather than Gb) is indeed an F# as it doesn't appear elsewhere in the scale.

How can you determine if a note is sharped or flatted if it doesn't exist in the scale? For example if Ab should be a G#?

Does it even make sense to imagine out of scale notes like this or am I thinking about it incorrectly?


1 Answer 1


Standard 7 note diatonic scales need to contain one of each letter name. Where there are chromatic notes, they will depend on what the original note was that's changed. For example, in key C, where the harmony makes an F minor chord, the changed note will be A♭, whereas the same pitch note making a C augmented chord will have the G changed to G♯.

When an interval is changed from major to minor, or diminished, the original note will be flattened or double flattened. If it's P5 and that gets augmented, it'll be sharpened. Not written as the next note up flattened. That way, readers can see how the harmony has changed, technically.

  • Thanks for your answer, I got a little lost when F minor was brought up, are you saying that the context of the rest of the music determines how it's notated? Commented Feb 1, 2019 at 17:11
  • Not really. More related to which note has actually been changed to form the harmony which needs the chromatic note. In F minor, there isn't G#, because it's spelled F Ab C. Hinges on what the original diatonic note would be before the change. There, it's A, not G.
    – Tim
    Commented Feb 1, 2019 at 17:14
  • hmm okay, what do you mean by harmony because it seems to have different meanings depending on context? I'll do some more reading tonight since I think I'm missing something. Commented Feb 1, 2019 at 17:17
  • I think what I'm missing is why F minor, how does that relate to this scale? Commented Feb 1, 2019 at 17:20
  • 1
    It's part of what's called the *parallel * key of C minor. F minor is found in pieces in C. That was just one example.
    – Tim
    Commented Feb 1, 2019 at 17:30

Not the answer you're looking for? Browse other questions tagged or ask your own question.