Harry Partch (1901 - 1974) is probably a lesser known legend in the world of "classical" music. I put the term "classical" in quotes because it, unfortunately - like the term "modern", usually tends to refer to a composer or type of music that uses orchestration. In reality the Classical period is the time in art from 1750 - 1820 . But I digress...
Partch was the type of American genius that could only come out of the cultural mix that is America.
"In 1930 Partch broke with Western European tradition and forged a new music based on a more primal, corporeal integration of the elements of speech with music, using principles of natural acoustic resonance (just intonation) and expanded melodic and harmonic possibilities. "
Along with that Harry Partch is also famous for inventing the 43-Tone Scale.
Partch may be best known for U.S. Highball, A Musical Account of Slim's Transcontinental Hobo Trip. A piece he based off his own travels from Caramel, California to Chicago, Illinois in 1941. Here's a clip below with a brief explanation.
Here's a clip from a 1968 documentary on Partch, with footage of Harry playing some of his invented instruments:
And here are clips to a 6 part BBC documentary on Youtube: