Flat Signs
This is a flat sign. A flat sign lowers the pitch of the note to which it applies by an interval known as one semitone or one half step. Thus the note Bb is one semitone lower than B.
Since the difference in pitch between the notes A and B is one whole tone (two semitones or one whole step), Bb is also one semitone higher than A.
The Note B Flat (Bb)
When a flat note is written on the staff, the flat sign is placed before the note.
The note Bb uses the same fingering as the note F. Practice alternating between these two notes until you can easily play either one.
The flat sign affects all B notes within the bar in which it appears. For example, in bars 2 and 4 the b sign appears before the first B in each bar. The flat also applies to all other B notes within that particular bar. The effect of a flat sign is canceled by a bar line, meaning that a new flat sign is needed to indicate a new Bb note in the following bar.
