Nuts and bolts … Bang on a Can All-Stars Mark Stewart, Robert Black, Ashley Bathgate, Vicky Chow, Evan Ziporyn and David Crossin.
The sound of a squeaking gate. The repeated belch of a leaf blower. A screwdriver drilling into an ear canal. For many, these are the sounds that come to mind with the words ''avant-garde music''.
Whatever the noise, it is still music - or at least it can be, according to one of the movement's most famous sons, John Cage. While English composer Ralph Vaughan Williams was penning his pastoral Fifth Symphony, across the pond Cage was busy sticking nuts and bolts into pianos, bashing metal sheets and other household objects in a gallimaufry of sounds designed to shake up the solar plexus.
Later in his career, Cage became even more creative, using the musical clattering of a bath-tub, five radios and a rubber duck for his composition Water Walk, which he performed in front of a giggling audience on an American TV game show.
His most famous - or, depending on your perspective, infamous - work is 4'33'', first performed to a bunch of confused New York holiday-makers at Woodstock in 1952, in which Cage does away with music altogether. For exactly four minutes and 33 seconds, the extraneous noises of the audience - feet shuffling, coughing and nose-blowing - become the soundscape, while the orchestra sits and does nothing.
Next week the Opera House will echo with the sound of silence when 4'33'' is performed as part of a two-day festival marking the centenary of Cage's birth. The festival will feature the Manhattan-based Bang on a Can All-Stars, an ensemble that includes musicians who knew and worked with Cage.
It has been 20 years since Cage died, but debate still rages about whether he was a composer or merely a court jester.
''He was an experimenter,'' says the director of Bang on a Can, David Lang. ''His experiments very quickly became questions not just for music, but for art, theatre and culture. He is someone who had a tremendous effect in all sorts of other disciplines.''
Cage liked to play chess with Marcel Duchamp and swap recipes with John Lennon. He was friends with Peggy Guggenheim and his partner was the choreographer Merce Cunningham.
In later years, Cage became interested in Eastern religions. Bang on a Can All-Stars will perform the famous work Indeterminacy, which was Cage's vocal and musical exploration of chance, influenced by his adventures with Zen wisdom and the Chinese manual I Ching, an old system of fortune-telling.
Cage collected a scrapbook of short stories that, when spoken aloud, had to be precisely one minute in length. The stories, some funny, others thoughtful and reflective, are read out at random while a piece of Cage's music is performed, creating a chance collision.
On many of his scores the notes are non-existent; they look more like computer algorithms or detailed maps than traditional music. Often abstract images for interpretation replace conventional crochets and quavers, and musicians follow a sonic outline of highs and lows, adding the detail themselves, becoming composers in the process.
To play Cage's music requires virtuoso precision and a high degree of sophistication, says Lang, who compares his work to that of another musical mathematician, J.S. Bach.
''His sonatas and interludes are like the Goldberg Variations; they are that big and that meaningful,'' he says.
But is it for everyone? In the past, audiences have stomped out of Cage performances and hissed at the musicians. What separates music from noise is the wonderful internal alchemy that happens when a sound triggers an emotional response. Is it possible to attain a heightened state of awareness by listening to someone blowing their nose? ''Look,'' Lang says, ''the thing that makes it music is not the sound but your openness to it. It's paying attention to it. 4'33'' is an incredibly beautiful piece.''
Cage's legacy is possibility. He gave other musicians, including Brian Eno and minimalist Terry Riley, permission to rehear the world and discover the beauty in surround sounds; the works of both of these artists will also feature at the concert. ''What Cage did is give us a way back to freedom,'' Lang says. ''We owe him a debt.''
The Composers: John Cage Centenary Celebration is at the Sydney Opera House on November 2-3.