TWO 20th CENTURY HARMONIC DEVICES...

Arguably the biggest development in C20 Western Music was Schoenberg's rejection of conventional TONAL HARMONY and invention of his SERIAL method of composition. Some C20 composers however used other harmonic techniques which were pretty much new as well, amonst them two that are concepts in Higher and Advanced Higher Music:

MICROTONE

This refers to any interval that is smaller than a semitone (in conventional TONAL HARMONY, as well as SERIAL HARMONY, the smallest interval used is a semitone.) Here are the opening bars of the first piece on the playlist, Szymanowski's 'Mythes'. Notice how he uses an upside down 'flat' symbol to represent a quarter-tone, and listen to the effect it produces:

While the microtones are used sparingly in 'Mythes', alongside more conventional TONALITY, the Czech composer Alois Hába wrote pieces that rely entirely on MICROTONES (eg. track 2). He even invented new instruments in order to  play these compositions.

MICROTONES can also be heard in some traditional music from Eastern Europe as well as in Arabic music and some Asian music (eg. tracks 5&6)



POLYTONALITY

This is the use of two or more keys at the same time. Here are two examples:

At the start of Milhaud's 'Botafogo' (track 1), the right hand of the piano is playing in F# major, while the left hand plays in F minor.

The prologue of Britten's opera 'Billy Budd' (track 2) features lower strings playing in E flat, and upper strings playing a CANON in C major.