Chromatic Harmonica
The chromatic harmonica has a button on the side which allows
you to play the normal major scale, and with the button
depressed, gives you all the half steps or notes in between.
This allows you to play any scale, in any key, but you can't
bend notes very well on this instrument so you don't get the
same "bluesy" sound as on the diatonic.
Reading music and song tab for the chromatic- The chromatic
harmonica hole layout is similar (sometimes referred to as
"Solo" tuning) to the diatonic hole layout (referred to as
"Richter" tuning), but not the same, so song tablature is
different.
Many accomplished chromatic players are able to read standard
music notation which eliminates the need for song tab. The
chromatic is mostly used for jazz, classical, and pop music- The
chromatic harmonica is typically used in jazz, classical, pop,
and music where the melodies require more than a 7-note scale
(like the one on a standard diatonic).
A classic example of where a chromatic would be required is the
theme song to "Midnight Cowboy". The original theme to "Sesame
Street" was also played on a chromatic.
People who play the chromatic harmonica- Stevie Wonder, Toots
Thielemans, and Larry Adler are three of the best known players
of this instrument.
The 40's and 50's were the heyday of the 'Harmonica Bands' (like
the "Harmonicats" and "Harmonica Rascals") and were usually led
by a chromatic harmonica player.