As part of my research for Part 2, I thought I would take a closer look at a composer who is well known for using untraditional scales – Claude Debussy. His piece ‘L’Isle Joyeuse’ for solo piano is one of my particular favourites, there is a recording where you can follow along with the sheet music here.
The first two bars seem decidedly chromatic with the the bottom note sliding down in semitones from a C# to a G, but looking more closely at the chords made up from the other notes you can see already it is based around a whole tone scale. After a few bars it appears to resolve into A major – but not quite; it retains the D# and G natural, so it is really a kind of hybrid of A major and a whole tone scale. The clashes between the D# and the E are very characteristic, and give the piece a playful and mysterious quality.
You can hear the hybrid major / whole tone scale throughout the piece, later on transposed into C major and the alternative form of the whole tone scale. Debussy uses the tonal ambiguity of the scale to good effect. Sometimes it sounds joyful (like the title of the piece) and other times more mysterious, depending on which intervals are predominantly used. For example in the pianissimo section marked ‘en peu en dehors’, the right hand is playing a dissonant augmented fifth which sounds a little unsettling, other times the music is focused around the major thirds of the scale which sound much more resolved and content.