Chromatic Harmonica Defined- The chromatic harmonica has a button on the side, which when not pressed in, allows you to play a normal major scale, and with the button depressed, gives you all the missing half-step notes in-between the major scale notes. This allows you to play in any key and any type of scale. It is typically used in jazz and classical music, but is found in all styles of music. Bending doesn't work nearly as well on the chromatic as it does on the diatonic harmonica and is used more for a "bending effect". In most cases, you will be doing good to bend a note a half-step down.