The missing notes on a regular bluesharp.
If we take an harmonica in the key of C:
- D# is missing in the low octave.
- D#, F#, Bb are missing in the middle octave.
If we take the 1rst and 2nd positions, these notes
correspond to the following degrees:
- D#: minor third in 1rst position.
- F#: flat fifth in 1rst postion.
- Bb: minor third in 2nd position and flat 7th in first position.
If we focus on the blues scale, we can notice
that there is only one missing note in the middle octave in
2nd position but this note (minor third) is very important.
In 1rst position, there are so many important
notes missing that the middle octave is unplayable (in blues).
This explains why most 1st position blues are played on the
low and high octaves.
Until quite recently, these missing notes were
a major problem for playing jazz or other elaborated styles
of music and contributed to confine the harmonica to the blues.
In the 80s, Howard Levy (an american piano and
harmonica player) started to popularize a new technique, called
Overblow, which allows to get the missing notes on regular bluesharps.
For the last decade many young players have followed this path
and open new territories to the harmonica. The Overblow technique
being quite difficult to master, some manufacturer and customizer
designed new instruments (based on the Richter tuning) allowing
to play the missing notes more easily.