After years of sparring, classical music and pop are getting friendly, at least on the edges.

In a movement often called "indie classical," young university-trained composers are using pop and rock instruments, electronics and chord structures at a level never seen before. Influenced by minimalists such as Steve Reich and Philip Glass, and liberated by composers such as Christopher Rouse, John Zorn and David Lang who use elements of rock in their works, these young composers are changing the sound of chamber music -- and its audience.

The young people opera companies and orchestras crave are coming out to the genre-bending indie classical concerts.

That's in part because some of the hippest pop artists are moving in the other direction, delving into classical techniques, and we are not talking just Billy Joel or Paul McCartney, Stewart Copeland or any other older rocker.

Radiohead's lead guitarist Jonny Greenwood did a residency with a London orchestra and then wrote a chamber orchestra work, "Popcorn Superhet Receiver." Folk artist Josh Ritter has collaborated with violinist Hillary Hahn, DJs have remixed Reich, and indie rock darlings Sufjan Stevens and Andrew Bird have used classical instruments in their songs. Groups such as Sigur Ros have blurred the line with essentially instrumental pop compositions. Rufus Wainwright is composing an opera. The list could go on and on.

Many indie classical artists are associated with the music label New Amsterdam, most notably Nico Muhly, a composer who has worked with Bjork. Two of the New York-based label's artists come to Pittsburgh this weekend for shows: singer Corey Dargel at The Andy Warhol Museum's Off the Wall series, and the NOW Ensemble at Pitt.

"People have such access to so much music it seems absurd that someone would not be influenced by a pluralism of music," says Dargel, 31. "What has changed in the last few years is that conservatories and music schools are being staffed by people who aren't concerned with barriers between music, but finding [the students'] own voice."

"I am just as likely to put in a pop or rock CD to listen to, even though I love the whole history of classical music," says NOW Ensemble composer and Pittsburgh native Patrick Burke, 34. "The music that is around me is rock and pop and post-rock."

Not that the instrumental music that NOW performs is rock, even though it usually includes electric guitar and sometimes plays in clubs.

"There is no way you could confuse it with a rock or pop band, but the influence of rock and certain pop groups is so strong in some of the pieces that it would appeal to people in the indie scene," says Burke.

At The Warhol, Dargel will perform his theatrical work "Removable Parts."

"It's a series of love songs about voluntary amputation," he says. "It is a real phenomenon people have, that they feel that a particular body part they have is foreign to them. This is beyond poor body image, it is compulsion to have a healthy limb removed."

His work is about where you draw the line. "We have a lot of ways of modifying our body -- going to the gym, getting piercings and so on. We can all relate and the love songs in the piece are about finding the connection."

The connection between classical music and popular music has been that of fist to jaw over the centuries, as the former looked down on the latter until the '60s, when rockers and their fans simply ignored classical. But now, everywhere you look -- for example, local groups Cellofourte and the newly formed Eclectic Laboratory Chamber Orchestra -- the two sides are meeting.

"I love going to the orchestra and even the new music played by it, but the place where the youthful energy has gone is somewhere else," Burke says. "We are turning into something different, something that can have a bigger audience and a future."