This is a very quick and blunt question but here we have a deliberately incorrect notation and below it is the corrected version (the black circles).

How come the eight note before the last (the pink) still has a flat accidental? That Cb note has been covered by the key signature anyway. The natural ends its effect as soon as the first bar is over, so that doesn't explain why this accidental has been placed either..

How Come?

  • 2
    That Cb note is an Eb note - note the bass clef.
    – Tim
    Jul 11, 2020 at 8:55
  • How'd you create the top example? Its key signature has E flat, D flat, F flat, and G flat.
    – Dekkadeci
    Jul 11, 2020 at 11:49
  • 1
    @Dekkadeci Not to mention a key signature of 8/9!
    – Richard
    Jul 11, 2020 at 14:10
  • 2
    The top signature is actually Cb, Fb, Bb, Gb (note the clef placement). Still doesn't make much sense to me. Jul 11, 2020 at 15:27
  • 7
    The OP states the first example is “deliberately incorrect”, probably from a textbook to help students recognize errors. Congrats, you all found them. :) Jul 11, 2020 at 17:06

3 Answers 3


The Cb note you mentioned is actually an Eb since this passage is in bass clef, not treble clef.

The accidental in bar 5 is a courtesy accidental (also called a cautionary or reminder accidental) and is not necessary but used to remind the player that the previous accidental has been cancelled. They typically are used a bar or two after the original accidental occurs (and preferably in parentheses) but sometimes they are used several bars after, as in this case.

  • See this type of question has popped up a lot recently. What I don’t understand is if it is normal practice for an accidental to only last a bar* why courtesy ones are added anyway? A few bars away seems awkward. Are they necessary for sight readers perhaps?
    – cmp
    Jul 11, 2020 at 7:53
  • 1
    There is no standard for this type of thing, it’s up to the composer, copyist and publisher I suppose. I think they’re good to have when sight reading and use them in my own charts if the next bar has a cancelled accidental but 3 or more bars later? I think it’s unnecessary. Still, a lot of published music has them bars later. Jul 11, 2020 at 7:56
  • Some publishers are just too kind! Maybe this one has a personal rule that whenever there's an accidental, the reminder gets printed on the very next time that note occurs again, but in its original form. But that could be twenty bars away! Where does one draw the line (no, not the barline...) ansd anyway, there should be a law saying 'always use parentheses for cautionaries'!
    – Tim
    Jul 11, 2020 at 9:01
  • 1
    @Tim, I should have mentioned the parentheses (I’ll remember to do it next time), not having them can actually defeat the whole purpose, it gives you that split second of: “What? Oh.” Jul 11, 2020 at 16:22
  • When I was a teacher, I always blamed the parentheses - come to think, still do...
    – Tim
    Jul 11, 2020 at 16:26

For some reason the top line in written in some kind subbass clef (with a really weird key signature). So the the third space is a C, but the second line is written in bass clef where the third space is an E (not a C).

The second line has an E-natural because this part is playing in the scale of F harmonic minor.

The last bar has an E-flat which isn't strictly necessary, but is some what useful because it is clearly showing that we have modulated to A-flat major.

It might be more modern/sensible to put this necessary accidental in parentheses (as a courtesy accidental).


I think it's a coding error in the program that typeset the musical examples.

I wouldn't trust any music typesetting program that let me supply 8/9 as a time signature and then lets me enter bars of 9/8.

Furthermore, the accidentals in the first sample don't agree with the clef. What music program would let you write that? Here's what Sibelius does with Ab major key signature and the Archaic Sub-bass clef:

enter image description here

So I think it is a coding error that there's a courtesy flat in front of the E in the fifth bar, rather than some little-known rule of music typesetting.


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