do they last until they are replaced by a different one? or just til the end of the measure?

also If say I have a B flat in the key signature that means every b is flat right, even like the one above the staff right?

If you have, say, a flattened A at the start of that bar, every A is flattened in that bar, unless there's a natural or sharp sign (or other accidental). In that case, the A becomes natural or whatever for the rest of the bar. Basically, the notes stay in whatever state the last accidental states.

And yeah, that means every B is flattened.

thanks man

An accidental only works within one measure and just for that line or space it's written on. Unlike the key signature, in which the flats or sharps affect every note with that name (say Bb) on any octave, an accidental only works for the specific pitch it's been written for. It means that if you write an altered B on the second line (bass clef, of course) and then you want the same altered B but one octave higher within the same measure, you must write the accidental for that note as well.

Another important remark about the fact that an alteration only works within a measure: This means that if you alter a B in a measure and that B appears again in the next measure without the accidental, the previous alteration doesn't work there. However, it's a common practice to remind that fact to the player writing the normal accidental (from key signature) between parentheses.

Hope this helps.

An accidental only works within one measure and just for that line or space it's written on. Unlike the key signature, in which the flats or sharps affect every note with that name (say Bb) on any octave, an accidental only works for the specific pitch it's been written for. It means that if you write an altered B on the second line (bass clef, of course) and then you want the same altered B but one octave higher within the same measure, you must write the accidental for that note as well.

Another important remark about the fact that an alteration only works within a measure: This means that if you alter a B in a measure and that B appears again in the next measure without the accidental, the previous alteration doesn't work there. However, it's a common practice to remind that fact to the player writing the normal accidental (from key signature) between parentheses.

Hope this helps.

hey sure does, I was reading a piece of music that did remind me after reading one that didn't and I was a little confused as to why it was telling me, guess it was just being nice haha but it made me wonder if I had my facts straight. thanks for the heads up