Nick Zinner isn’t your average orchestral composer. The 37-year-old guitarist with the Yeah Yeah Yeahs refers to the movements of his new work, 41 strings, as “tracks”, and when I ask if the seasonal structure was based on Vivaldi’s The Four Seasons he readily admits, “I couldn’t even pick out that symphony [sic] if I heard it.”

So what’s he doing writing an extended piece for a string section of 41 players, to be performed at the Sydney Opera House in its Australian premiere? In recent years the skinny indie rocker has branched out from his work with his New York three-piece to score films, but this latest commission, celebrating the 41st anniversary of Earth Day, called for larger forces than he had dealt with previously.

Why 41 – surely there are more monumental milestones to celebrate? “Earth Day had done an event called 40 drummers for their 40th anniversary in 2010,” Zinner explains. (The director of that project, The Boredoms’ Hisham Akira Bharoocha, plays drums in 41 Strings and leads a percussion set in the concert’s first half.)  “So the following year they wanted to top that and they approached me to write something for a performance in New York.”

And why strings this time round? “They...