Today’s musicians tend to react to the above question with raised eyebrows. Isn’t it clear – accidentals in the key signature are always in force and for all octave registers unless annulled by natural signs. An accidental found in a measure is valid for this note and for the entire measure – no longer, no shorter. But this was not always so.
For instance, there were other rules in Johann Sebastian Bach’s time. Key-signature accidentals were indeed used as they are now, though the accidental placed within a measure was valid only for this one note. If the same note was later repeated in the bar, then the accidental had to be given again in order to be further valid. Continue reading
