There are seven pedals on a concert harp. Each pedal can be in a high, middle or low position. The strings of the harp can be thought of like the white notes of a piano, tuned to naturals (C,D,E etc.). Each pedal can change one of the letter-named notes one semitone higher or lower. For example: the pedal on the left changes all the Ds to D flat (if the pedal is in the highest position) or D sharp (in the lowest position). From left to right the pedals operate the Ds, Cs, Bs, Es, Fs, Gs and As.