Text of Light, the revolving New York ensemble formed in 1999 by guitarists Lee Ranaldo and Alan Licht, performs improvisations while films play in the background. That description may seem odd, as if the music and images are unrelated events. But Text of Light’s work takes a unique approach to the mixing of sounds and pictures.

With the noisy strings of Messrs. Ranaldo and Licht, the rattling percussion of William Hooker and Tim Barnes, the dislocated samples of DJ Olive and Christian Marclay, and the droning sax of Ulrich Kreiger, the group’s swirling music is less a soundtrack than part of a spontaneous audio-visual dialogue. Since 2004,Text of Light has released a handful of live recordings, most in small, limited editions. Its latest effort,”Metal Box” (Dirter Promotions) is a leap forward in size and scope.

Calling Text of Light’s concerts “realtime mixed media collage,” Mr. Licht (a sometime New York Sun contributor) has likened his group to a mosh pit at a punk rock show. Just as moshers rarely sync up to the beat of onstage sounds, Mr. Licht and his bandmates react more to the energy of the films and one another than the timing of the images.

Those images come mostly from the late filmmaker Stan Brakhage. Over a 50-year span, Brakhage made more than 300 films exploring abstract light and motion. Messrs. Ranaldo and Licht named their group after “The Text of Light,” Brakhage’s 71-minute montage of rays refracted through a glass ashtray, and have performed with it and other Brakhage works, such as “Dog Star Man” and “Scenes From Under Childhood.”

Brakhage made these films without sound, and Text of Light’s performances have rankled purists who feel they should only be screened in silence. But Brakhage didn’t object to his films being used in other contexts, provided the new work was not billed as a screening or collaboration.The group has followed those wishes, earning the approval of Brakhage’s estate.

“Metal Box” consists of 3 CDs housed in a circular metal case, an homage to the film-can packaging of a 1979 triple LP (also called “Metal Box”) by British post-punk band Public Image Ltd. The group’s initials even appear on the cover as “ToL,” mimicking Public Image Ltd.’s iconic “PiL” logo.

The range of sounds on “Metal Box” is wider than on previous Text of Light releases. Disc One, taken from the group’s first show in May 2001, wraps Mr. Ranaldo’s chiming guitar (reminiscent of his work in Sonic Youth) around Mr. Marclay’s violin-like strains and Mr. Hooker’s rumbling drum clusters. The pulsing sounds sprout randomly at first, but eventually congeal, culminating in the 17-minute “052901 Tonic 3,” an aural séance of hypnotic drones and clanging beats.

Disc two is even more varied. Sampling from three different performances and two studio recordings, it includes intriguingly wry samples from Messrs. Marclay and Olive; a spoken recitation of James Joyce’s “Chamber Music” by the Licht-led Digger Choir mixed with guitar and sax noise; and a 2003 Berlin performance that builds so dramatically it feels more like a pre-composed symphony than an improvisation.

A single, hour-long concert recorded in Scotland in 2004 takes up most of disc three. The array of sounds is again impressive.Absorbing this music takes patience — much like Brakhage’s long, abstract films.

But Brakhage rewards such patience, gradually stripping the viewer of preconceptions and inspiring new ways to watch and think about moving images, and, at its best, Text of Light’s work has a similar effect. Just as the group’s performances redefine how sound and picture meet,”Metal Box”expands the definition of music to include nearly every sound imaginable.