DAVID LANG first heard Wagner’s “Tristan und Isolde” at the San Francisco Opera in 1974, as an undergraduate student and aspiring composer. This was the first opera ticket — standing room — that he had paid for with his own money, and he arrived well prepared, with a copy of the score and a flashlight to study it by.

“It was a really big deal for me,” Mr. Lang, now 55, said recently, sitting on a sofa in his light-flooded SoHo loft while two parakeets called noisily for attention from another room…

At the Barbican Centre in London, on March 20, 2012, the Bang on a Can All-Stars premiere Field Recordings — with new works by Gordon, Lang and Wolfe. The evening-length project that is as much a mystery as a concert – a kind of ghost story. The ghosts aren’t the physical presence of people gone before, but they are the ghosts of sounds, images, ideas, and voices. Each composer has been asked to find and interact with something recorded before, using the power of music made right in front of us to reach out to other things not present…