The PRISM Quartet is redefining the outer boundaries of music again, this time with video.

The Philadelphia-based classical saxophone quartet is using experimental technology to compose not only what the audience hears, but also what it sees — on four video screens — for its "Breath Beneath" concert tonight at Drexel University's URBN Center Annex, part of the Fringe Festival.

The basic concept isn't new, admits the quartet's executive and co-artistic director Matthew Levy: "There have been a lot of contrived efforts to throw video up against music … but this is a way of expanding our expressivity and finding new ways to share our emotions and intellect."

One work on the program, a new score by Princeton-based composer Dan Trueman titled Waveguide Model I, consists of musical modules (the composer calls them "conditions") that the individual members can play at will — and in reaction to each other.

Accompanying images from filmmaker Mark DeChiazza are also open to on-the-spot interaction, thanks to onstage microphones that have nothing to do with amplification: They're picking up on the amplitude of what each quartet member is playing — often according to the person's onstage positions — and funneling that information to help shape the visual images.

How that might work: At a recent rehearsal in Princeton, super-saturated yellows on the video screens seem to penetrate the weedy depths of a sunflower, each from a slightly different angles on each video screen. But as Levy played more squiggly ornamental figures, the edges of the images because more elaborate. Then the image effortlessly divided into self-mirroring images like a Rorschach test.

Who knows how that sound information will be visually processed the next time, whether at tonight's performance or Friday's repeat at the New York's 3-Legged Dog Art and Technology Center.

"It's akin to surfing. You don't have to take every wave. But if it fits where you want to go, you take it," said DeChiazza.

The goal: "Something that's honest and participatory and integrated," said DeChiazza.

Not every group would be up for this sort of thing, much less embrace it. But due to lack of modern saxophone quartet repertoire, PRISM has commissioned 250-plus pieces in every possible style. And besides having heard everything, Levy is the son of two visual artists, so he has also seen a lot.

The idea is not necessarily to bridge the impossible gap between audio and visual, which are as separate as earth and sky. "We're looking at how they can rub up against each other and feel more urgent," said Trueman. "They're supposed to be co-existing and prodding each other in different ways."

Interactive technology has been around in various shapes and forms (including lighting designs at stadium concerts), and this "Breath Beneath" concert is intended to be a cross section, with five pieces showing different states of interactive audio-visual evolution, many of them embracing chance elements.

"We're hoping to discover something we hadn't planned," said filmmaker Bill Morrison, who is employing 1920s film footage of dance (ragtime, Charleston, etc.) in varying states of black-and-white decay, for Julia Wolfe's 2015 composition Cha. The music itself is about the Pulitzer Prize-winning composer's Latin-dance upbringing in Montgomery County — so the video isn't illustrating the piece but going for a synergistic incongruity.

Other pieces include Hymn by Kati Agocs and two works by composer/videographer Jacob ter Veldhuis (aka Jacob TV). His Heartbeakers includes clips from The Jerry Springer Show with tales of broken relationships. Body of Your Dreams deconstructs an infomercial about some sort of waist-slimming device.

Though the team admits to extreme weariness of staring at computer screens, PRISM's audio-visual endeavors are part of a long-term artistic conversation that Levy hopes will evolve into a new, full-evening piece that will make this week's concert look like what it is:  a pilot for something far bigger.

"Tech is getting smaller, easier, and fast," says Trueman. But if there's a godfather in this concert, it's not some audio-visual guru, but the late John Cage (1912-1992), who was once thought to represent the lunatic fringe of classical music but whose concepts of embracing chance elements in performance are increasingly mainstream.

"And that's a good ghost to have in the room," said Morrison.


PRISM Quartet "Breath Beneath" concert

Performance at 7 p.m. Thursday at Drexel University's URBN Center Annex, 3401 Filbert St.

Tickets: $15.

Information: 215-413-1318 or