(a,b) The keyboard of the 19-tone piano differs from that of the traditional 12-tone piano in that it has seven additional keys in each octave, forming a diatonic scale “opposite” to the principal one, on the white keys. The black keys, as usual, correspond to a pentatonic scale. Accordingly, new signs of alteration appear that can be found in some modern compositions: a “half-sharp” raises a tone by one degree of the 19-tone scale; a “half-flat” lowers a tone by one degree. A “whole tone” contains three steps of the scale, a “semitone” (the distance between mi and fa) contains two steps of the scale. In addition, an “introductory semitone” corresponds to the interval of one step of the scale [21]. Introductory intervals are widely used in music, though they are poorly reproduced on 12-tone tempered instruments.
(c) The ascending chromatic scale of C major differs here from the descending major chromatic scale, as well as from the minor chromatic scales and the major-minor scale. These scales are represented by the same 12-note sequence in the 12-tone scale.
(d) An example of a “hypermode” of 12 tones that cannot be reproduced in the 12-tone scale.