At the intersection of avant-garde music and graphic design lies "graphic notation," the visual expression of a musical composition that's outside of conventional music notation systems. Theresa Sauer's book Notations21—inspired by John Cage's Notations (1969)—collects stunning examples of graphic notation by Cage and other 20th and 21st century experimentalists. Unfortunately, the book is out of print and fetches a high price online, but you can see more examples from its pages over at Classic FM.
Above: Portion of George Crumb's "Twelve Fantasy Pieces after the Zodiac" from 1972 (listen here). Below, portion of John Cage's "Aria" from 1958 (listen here); and Cornelius Cardew's "Treatise" from 1963 to 1965 (listen here).
(Thanks, Jason Gresl!)