SUBSTITUTE ...
The late guitarist, composer and certainly no stranger to the tritone, Pat Martino, pictured here at the Cheltenham Jazz Festival in 2009
PHOTO BY STEVE THORNE/REDFERNS/GETTY IMAGES
The term tritone refers to an interval that spans three whole tones. For example, this could be: C to D, D to E then E to F#. However, another way of looking at it could be as an augmented 4th (C to F#) or a diminished 5th (C to G b). As you can see, these are all different names for one specific sound. Once we get into chord progressions and ‘diatonic speak’ such as II-V-I, you may well come across the term ‘tritone substitution’. All this actually means is that a chord within a progression (usually the V) has been exchanged for another with the root a tritone away.