Watch the Blue Notes online guitar lesson by Annie Raines from Blues Harmonica Blueprint
BLUE NOTES: Blue notes are commonly defined as flattened thirds, fifths and sevenths in a scale. Cross harp position gives you a full complement of blue notes when you bend down the 1 draw, the 2 draw, the 3, the 4, and the 5 - even though you technically aren’t playing another note when you bend the 5 draw, flattening down that dominant 7th is like saying "how blue can you get?" Adding just one blue note to a pentatonic scale can turn it into a blues scale.
Blue notes can also be defined subjectively in that the 3 draw bent down a half step, for instance, doesn’t have to be played at the precise pitch of Bb to be a blue note. It could be a little flat or sharp of center and sound dirtier or sweeter as a result, and that’s a big part of what playing blues is all about.