However, on 2 occasions in the octave there is a semitone interval between 2 white notes. A chromatic semitone can be manipulated to be a diatonic semitone and vice versa. For example here is an ascending chromatic … The above is from Chromatic semitone, which now redirects here. A semitone, also called a half step or a half tone, is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically. Move right one more semitone, and you’ve got a WHOLE TONE. i.e.