I was watching Music Matters' video on counterpoint when I came across this chord progression:

| I V | I V IV | II♭ V I VI I♭ | II♭ V I ||

My question is what is a I♭ chord. Is this chord common? Is this correct notation (vs VII)? Does it have a name (like the neapolitan chord after it)? Does it have a conventional use?


1 Answer 1


I think, based on the co.uk domain, and the instructor's accent, that those are not flat signs, but British inversion signs.

a = root position

b = first inversion

c = second inversion

I'm also assume the system used doesn't change letter case for major/minor qualities.

So, it means | ii6/3 V I vi I6/3 | ii6/3 ... in the system that I'm familiar with.


  • So it's neither b or ♭ but 6? Nov 19, 2021 at 0:26
  • 11
    This is exactly what the instructor says ("two bee, or two in first inversion") if you watch the video for about a minute and a half.
    – user39614
    Nov 19, 2021 at 0:26
  • @user1079505, in that system it is a letter, lower case "b". If you use Arabic numerals, like in figured bass, it would be a 6/3 or for short just 6. All of them meaning a first inversion chord. Nov 19, 2021 at 0:38

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