Page "Harmonica" Paragraph 24

There are eight kinds of orchestral melody harmonica: the most common are the Horn harmonicas that are most often found in East Asia.

These consist of a single large comb with blow only reed-plates on the top and bottom.

Each reed sits inside a single cell in the comb.

One version mimics the layout of a piano or mallet instrument, with the natural notes of a C diatonic scale in the lower reed-plate and the sharps / flats in the upper reed-plate in groups of two and three holes with gaps in between like the black keys of a piano ( thus there is no E #/ Fb hole nor a B #/ Cb hole on the upper reed-plate ).

Another version has one " sharp " reed directly above its " natural " on the lower plate, with the same number of reeds on both plates.