The effect of accidentals?

[n3wb13]

Hello, I'm reading 2 books about music theory.

Basic Music Theory: How to Read, Write, and Understand Written Music ( Sol-Ut Press )

When an accidental is used at the beginning of a measure, it’s effect lasts for the entire measure. For example, if at the beginning of a measure we have a B flat, and then at the end of the measure there is another B, it is also a B flat unless there is a natural sign in front of it. An accidental can’t have an effect over a bar line.

Esential Dictionary of Music Notation ( Tom Gerou )

An accidental affects all the subsequent notes of same pitch within a measure.

So I'm confused that an accidental to have effect on all other notes that have same pitch within a measure, it must be be placed at the very beginning of the measure ( right after the bar-line ) or it can be anywhere between 2 bar-lines but the note must be the first occurrence in the measure? Thanks so much

[faulty_damper]

Yes, if you have an accidental in front of a note, it affects all notes AFTER it in the same measure; it would not apply to previous notes of the same pitch.

[scottmcc]

correct.  for clarity, there is often a "courtesy" sharp, flat, or natural to indicate when the accidental is no longer used, especially if an accidental is used several measures in a row before it is not used again.  but this is not a universal style of writing.

[n3wb13]

Yay I got it Thank you all very much for your answer.

[nystul]

correct.  for clarity, there is often a "courtesy" sharp, flat, or natural to indicate when the accidental is no longer used, especially if an accidental is used several measures in a row before it is not used again.  but this is not a universal style of writing.

Those "courtesy" naturals absolutely drive me crazy.  When they occur in a tight chord, it leads me to sight read the chord wrong almost every time, because my brain just automatically rejects the right conclusion and looks for a flat or sharp note to attach that natural to.  Just today I was playing a rag that had a f flat in one measure then the next measure f natural.  I've played this piece so many times and I always hit d natural there instead of d flat.  Today I caught it and wondered why, and it's because of that unnecessary natural on the f.

[jbmorel78]

Those "courtesy" naturals absolutely drive me crazy. 

Of course there is the issue of clutter, but sometimes they can be helpful!  In contemporary music, where tonality can be quite promiscuous, I find myself grateful for these little devils.  I played a piece by Joseph Schwantner which involved a lengthy tone row, which appeared later in canon, and courtesy accidentals saved my life: In fact, in the preface to the score, Schwantner instructs the pianist that in the work in question, accidentals only apply to the note which they directly precede.

In my view, some composers employ courtesy accidentals more effectively than others, and there is a balance that must be maintained between clarity for the performer, and security for the composer that there will not be a misreading.  In any case, sometimes courtesy can be a nuisance!

JBM

[Bob]

I had a music theory prof who put courtsey accidentals in parenteses because he didn't want to insult the perfomer. ("Hey dummy, it's back to the way it was here in case you weren't paying attention.")   It added even more clutter.