Piano World Home Page Forums Our Most Popular Forums Adult Beginners Forum Can someone list the rules of accidentals?

I have a measure where the natural accidental cancels a sharp in the key for the whole measure. Business as usual.

Then, there is another measure where the natural accidental is shown on two of the same note, canceling the sharp each time apparently, and then the remaining two notes are actually sharp. I find this odd.

So, what if the music wants to cancel the first sharp, and not the rest?

I can't seem to find rules this detailed. Was there supposed to be a parenthesized courtesy sharp (#) accidental post natural?

I've already read the wiki page listed below, plus many others!

My understanding is that the accidental will begin where it is first written and continue throughout that bar or until another accidental cancels it. Accidentals don't affect the same note in a different octave. The same note on different octaves would need their own accidental. Once you hit a new bar all the accidentals are gone and you are back to the normal key signature notes.

Sometimes the editor will put unnecessary accidentals, often at the start of the next bar, to remind the player that things are back to normal. I don't seem to recall seeing them in parentheses though, but I am sure I have and just can't remember.

Key signature changes however carry on until the key signature changes again

Wiki - Accidentals

Can you post pictures of the two measures in question? And some measures around them, too, would be helpful for context.

I find it odd, too. If they wanted to re-sharp a note, they need only do the first of the two that was supposed to be sharped.

Cautionary accidentals occur after the bar line when a previous measure has an accidental, and the next measure goes back to the key signature automatically and they are providing the accidental just as a reminder.

Since an accidental stays accidental throughout the entire measure after it occurs, it would not revert back to the key signature (sharp) in your example unless the sharp were actually given again.

An accidental in a measure holds until end of measure (unless the note is slurred over to next mwasure). Or until the next accidental.

I'm not sure what if the next accidental is a natural sign, the key's accidental is one sharp and the accidental was a double sharp. I guess most composers would put extra stuff there to make sure what's intended then.

If the accidental is superfluous, it MAY be in brackets eg (#). But I think the brackets are optional.

Here is an interesting article from Henle on the subject:

http://www.henle.de/blog/en/2012/09...onary-accidentals-or-are-extras-o-k-too/

Other systems of accidental notation are in professional use by some composers, these are far from mainstream but they are out there.

What composition and measures are you referring to xorbe? I am interested to have a look.

Those Henle guys...it sounds like they but some thought into their work!

I agree with PianoStudent88, you should post the score.
There are indeed two possibilities; one, as MALDI_ToF guessed, is that those "same notes" are actually on different octaves. So e.g. the first natural applies to Do3, the other one applies to Do4, and then when you encounter Do3 and/or Do4 again in that measure you simply keep playing them naturals, since this is the rule; if the score wouldn't have put the natural on Do4, that Do4 would have had to be played sharped, because an accidental only applies to the note on that particular octave.
If, instead (second possibility), the notes are in fact in the same octave, then the second natural is a courtesy accidental; in fact they are sometimes used even without the parenthesis, to avoid high markings density in the measure.


No. I agree with Morodiene's answer on this.
Those notes remains naturals for the entire measure. So if there could be courtesy accidentals on those notes they would be naturals between parentesis, to remind you that those notes should be played natural.

The rules of accidentals are rather simple.

First the piano is made up of semitones, 88 of them, most of the time. The F to F# is one semitone. The G to G# is one semitone. The E to F is one semitone and so is the B to C, one semitone.

A sharp raises a note by one semitone
A flat lowers a note by one semitone
A natural cancels a sharp or a flat

Not all sharps or flats occur on black keys. The B is also a C-flat. The F is also an E-sharp.

With accidentals, we can change the name of a note without changing its pitch. This is an enharmonic change. For example, B-flat and A-sharp are both the same pitch and enharmonic.

When a note has been altered by an accidental, it remains altered for the remainder of the measure, unless it is changed by a new accidental.

An accidental does not raise or lower same pitches in other octaves. Just that one pitch. A key signature raise or lower all the same octave pitches. So in the key of G, all the F's on the piano are raised one semitone to F-sharp. In the key of F, all of the B's on the piano are lowered one semitone to B-flat.

Also, an accidental can be a courtesy accidental. For instance, in the key of G, there is an F-sharp in the key signature. If the F in the music is also sharped, it is a courtesy, a reminder. It does not mean two sharps, one from the key signature and one next to the note (double sharps are denoted by the accidental that looks like an x). It is still F#. With the key signature of G, you play the F# if there is an # accidental next to the F, and you also play the F# if there isn't. This applies to flats and naturals as well.

Hope this helps.