Music in Vernacular by Turtle Island Quartet : Jazz: The no-borders, all-music string quartet plays tonight at Royce Hall.

Some call it new acoustic music; others refer to it as world music. The Turtle Island String Quartet, to whom these and other phrases have been applied, prefers the term vernacular music.

Call it what you may, this group, which performs tonight at Royce Hall, has been the catalyst for an unprecedented category: The no-borders, all-music string quartet. These four musicians--violinists David Balakrishnan and Darol Anger, violist Katrina Weede, and cellist Mark Summer--collectively can claim experience in classical music, jazz, bluegrass, folk, new age, rock and pop.

“We weren’t the first string quartet to play jazz works,” says Balakrishnan. “Six years ago the Kronos Quartet played tunes by Bill Evans and Thelonious Monk.” But, he could have added, when improvisation was called for, the Kronos had to bring in outsiders like Jim Hall and Eddie Gomez or Ron Carter to provide an ad lib touch. The Turtle Island Quartet, on the other hand, comprises four built-in improvising musicians.

It was the quartet’s approach to jazz standards that earned a Grammy nomination for Balakrishnan, in the instrumental arrangement category, for his chart on “A Night in Tunisia,” in the quartet’s first album for Windham Hall Records. Jazz standards also dominated the second set, “Metropolis.”

These successes emboldened the group to step into even more unfamiliar territory. Last year they performed the score of a Michael Caine movie, “A Shock to the System.” As Darol Anger says: “This was quite a challenge, as it was all new music, written by a fan of ours named Gary Chang.”

The latest album, “Skylife,” is largely an in-house creation, with six originals by Balakrishnan and/or Anger, one by Weede, and two works by Summer.

“We’ve found that people are really responding to the fresh material just as they did to the familiar jazz standards,” says Balakrishnan. “We’ll be playing several of them at Royce Hall.”

The success of the Turtle Island Quartet (its name was taken from an American Indian term for North America) has paved the way for other such units: The Greene String Quartet, the Uptown String Quartet (with Max Roach’s daughter Maxine Roach on viola), and the Black Swan Quartet, which includes a bassist. The readers’ poll in Jazz Times Magazine this year instituted a category for string groups, something that would have been impossible a few years ago. (Turtle Island won, while the Uptown Quartet came first in the “Emerging Talent” sub-category.)

A year ago the first personnel change took place in Turtle Island: Irene Sazer, who had switched from violin to viola in order to give the group an orthodox string quartet instrumentation, decided to strike out on her own and was replaced by a full-time violist, Katrina Weede.

“I quit the symphony business three years ago,” says Weede. “It just wasn’t doing anything for me, and I decided that jazz would. I already knew Mark Summer and Irene, and I started taking lessons with Dave. I got into a scene where everyone was doing this; I needed to find a true creative outlet.”

Weede was born in Michigan but raised in Los Angeles. She studied at Cal State Northridge and played for seven years in the American Youth Symphony. “We used to perform a lot at Royce Hall, and I would fantasize about being a soloist and walking out on that stage. David felt the same way, ‘cause he went to school at UCLA; so our dreams have been realized.”

Since “jazz violist” is virtually an oxymoron, Weede has turned to other instruments for her sources of inspiration. “My hero this week is Sonny Rollins. It changes from week to week. I spent a long time transcribing Lester Young solos off the records, and I’ve just started working on some Coleman Hawkins stuff.”

Weede has graduated into writing for the group; her “Mr. Twitty’s Chair” was a highlight of the recent album. She has since made an arrangement of Horace Silver’s “Calcutta Cutie.”

Although Mark Summer occasionally plucks his cello in the manner of a jazz bass player, the quartet has functioned without a conventional rhythm section. This situation, however, will soon change. “We’re going to collaborate with Billy Taylor,” said Balakrishnan, “playing his ‘Homage,’ a 30-minute suite, with Billy on piano as well as his bass player and drummer.”

From New York, Taylor elaborated: “It’s in three movements, dedicated to the memory of four great string players I worked with: the violinists Eddie South and Stuff Smith, and the bassists Oscar Pettiford and Slam Stewart.

“I originally composed it for the Juilliard Quartet, and I’ll be premiering it with them in January; but later it will be performed with the Turtle Island Quartet in Massachusetts and San Francisco. I’ve already rehearsed with them and they are just extraordinary musicians.”

“This is a new experience for us,” says Balakrishnan. “After rehearsing with Billy’s trio I realized how great it would be to do some more work with a jazz rhythm section.”

Meanwhile, without rhythm attached, the Turtle Islanders continue to make their own contribution to history by demonstrating that the phrase “with strings,” finally has a new, positive meaning and a durable future.