ZAPPA'S GENERAL DEFINITION OF MUSICAL COMPOSITION

"A person with a feel for rhythm can walk into a factory and hear the machine noise as a composition. If we expand that concept to include light, behavior, weather factors, moon phases, anything (whether it's a rhythm that can be HEARD or a rhythm that is PERCEIVED, i.e., a color change OVER TIME -- or a SEASON), it can be CONSUMED as music. If it can be CONCEIVED AS MUSIC, it can be EXECUTED AS MUSIC and PRESENTED TO AN AUDIENCE IN SUCH A WAY THAT THEY WILL PERCEIVE IT AS MUSIC.
     ...Music, in performance, is a type of sculpture. The air in the performance space is SCULPTED INTO SOMETHING. This "molecule-sculpture-over-time" is then "looked at" by the ears of the listeners -- or a microphone. ...A composer is a guy who goes around forcing his will on unsuspecting air molecules, often with the aid of unsuspecting musicians."

- Frank Zappa

(source: Zappology: The Closest Look at the Music and Lyrics of Frank Zappa http://www.mindmined.com/public_library/nonfiction/chris_federico_zappology.html#freak)