Chromatic harmonica Chromatic harmonica The chromatic harmonica is a type of harmonica that uses a button-activated sliding bar to redirect air from the hole in the mouthpiece to the selected reed-plate desired. When the button is not pressed, an altered diatonic major scale of the key of the harmonica is available, while depressing the button accesses the same scale a semitone higher in each hole. Thus, the instrument is capable of playing the 12 notes of the Western chromatic scale. The chromatic harmonica can thus be contrasted with a standard harmonica, which can play only the notes in a given musical key.
Transposition (music) Thus the set ("A") consisting of 0–1–2 transposed by 5 semitones is 5–6–7 (T("A")) since , , and . There are two different kinds of transposition, depending on whether one is measuring intervals according to the chromatic scale or some other scale. In chromatic transposition one shifts every pitch in a collection of notes by a fixed number of semitones. For instance, if one transposes the pitches C–E–G upwards by four semitones, one obtains the pitches E–G–B. In scalar transposition one shifts every pitch in a collection by a fixed number of scale steps relative to some scale. For example,