# When does a changed flat sharp or neutral revert back to it's original form?



## Manok

I've been using Sibelius for awhile, and I think it's severely confused me. Whenever you add an extra sharp or flat, you have to add that sharp or flat to every same note in that same bar to get it to sound the same. I know that across one bar that it stays the same, my confusion is, what happens on the next bar? Does it revert back to the original configuration? When does it change? I'm learning the first Debussy Etude (pour les cinqs digoits) and I can't decide if the e that is changed once should stay changed, until there is a natural along the way, or if it goes back to being a natural on the very next bar? It's been a very long time since I had piano lessons. (over a decade)


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## Heck148

Generally, "accidentals" prevail thru that measure, then revert to original in the next measure.


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## jegreenwood

Usually published music will mark the first reversion as a "courtesy."


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## Taggart

Depends on the period, the octave and the stave. 

Baroque (and earlier) music assumed that the accidental only applied to the given note. Modern editions will add the corrections to the next note. Later music says the accidental applies to the whole bar / measure.

If you have an F natural (either stave) and make it sharp, then the F an octave above (or below on the same stave) will still be an F natural unless you add an accidental. Octaves are independent of each other.

If you have an F natural on one stave then any F on the other stave will be an F natural - even if it the same note (with ledger lines). Staves are independent of each other.


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