A question about enharmonics and register

Take a C, for instance. Its enharmonics are B# and Dbb.

What’s the correct octave notation? B#4, C4, Dbb4 or B#3, C4, Dbb4?

The same for Cb. Its enharmonics are Ax and B. So Ax4, B4, Cb4 or Ax4, B4, Cb5?

The question comes from a development for Fretful.io (fretboard visualizer) - Alpha release. I need to understand if I came across a bug or if the octave register is just wacky.

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According to Wikipedia:

The octave number is tied to the alphabetic character used to describe the pitch, thus:

  • “B3” and all of its possible variants (Bdouble flat, B♭, B, B♯, Bdouble sharp) would properly be designated as being in octave “3”.
  • “C4” and all of its possible variants (Cdouble flat, C♭, C, C♯, Cdouble sharp) would properly be designated as being in octave “4”.

In describing musical pitches, nominally enharmonic spellings can give rise to anomalies where, for example in meantone temperaments C♭
4 is a lower frequency than B3; but such paradoxes usually do not arise in a scientific context.

This reddit thread is also worth looking through: https://www.reddit.com/r/musictheory/comments/67uqni/is_cflat_4_the_note_one_semitone_below_middle_c/dgthm9l/

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Are you still looking for answers on this?
I don’t have them but I do know who to tag if you still need it.

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Thank you Eric, I figured it out. As I suspected:

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Cool.

I was just going to recommend some people to tag. There’s @JoshFossgreen and @Gio, but there’s also @joergkutter, @PamPurrs, and @tamaraster, (and others I’m probably forgetting right now) that can help out a lot on theory questions.

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Western music isn’t meantone tempered, so you don’t have to worry about this!

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