At age 16, she enrolled in a music school in Edinburgh, where the orchestra was short of violists, so Cook was introduced to the alto member of the string family. “It seemed to suit me,” she says. “The richness of the viola sound appealed to me.”

Cook continued her viola studies at the Guildhall School of Music & Drama in London. She credits her main professor there, David Takeno, as “the biggest influence on my playing. He was a wonderful teacher because he taught me to think for myself. If I asked him how to do something, he’d reply with a question that would force me into finding the answer for myself. A lot of players, when they’re learning a piece, will just ask for their teacher’s fingerings. People don’t ask enough questions of themselves, and rely too much on their teachers to tell them what to do.

“Another thing he taught me is that if I was playing something and wasn’t as convincing in a phrase as I ought to be, he’d make me play the phrase five different ways. But he wouldn’t tell me which one sounded best. He wanted me to learn to play everything five different ways, and in the concert decide on the spot how to do it.

“So my playing is more intuitive and spontaneous from learning that way. I don’t necessarily figure everything out down to the last semiquaver. I have a different palette of colors to choose from in a performance.”

It was at Guildhall, around 1996, that Cook first heard O’Connor’s Appalachia Waltz CD, featuring Yo-Yo Ma and Edgar Meyer. “I got the CD and I loved what he was doing,” she says. “Here was somebody bringing fiddle music into the classical world.”

The two worlds remained separate for Cook over the next several years, though, as classical work occupied more and more of her time. At one point, she was all set to take a job as principal violist with the Australian Chamber Orchestra, but O’Connor talked her into remaining in the United States. He had transcribed the music he’d done with Ma and Meyer for violin, viola, and cello, hoping to make the pieces accessible to more players that way, and he was trying out the arrangements with Cook and Haas.

“From the moment our bows touched the strings on that material, it felt so natural,” says O’Connor. “They completely got the program, the music, the style, how to blend, how to meld their classical training into their folk-music experience. I went, ‘Wow, here’s the group I can finally play this stuff with.’”

Says Cook, “What I do in that trio is much more classically oriented than Scottish fiddling, but the roots are still there. Even though it’s American fiddling roots, it’s the same rhythmic basis of the tunes that comes with playing folk music. You don’t play the eighth notes straight; they have a bit of a swing to them, the way a lot of jazz players do it.”

Cook knew she couldn’t make a living solely through O’Connor’s new Appalachia Waltz Trio, but at his request she stayed in America anyway. Luckily, she landed the principal-viola slot at Chicago Lyric Opera, which occupies her steadily for six months, leaving her free the rest of the time to work with the trio.

Cook is reputedly great fun to be around, although her friends are reluctant to share any anecdotes for publication. Her Lyric Opera stand partner, Frank Babbitt, after alluding to antics with chocolate on the music stand, hints that the violist has a dark side. “Carol does have a few glaring faults,” he reports, “such as hanging out with trombone players and an aversion to sensible shoes.”

More seriously, Babbitt reports, “I wish I could somehow take a bit of credit for showing her the operatic ropes, but the fact is: Carol is a natural and she fit right in from the very first . . . I’ve also enjoyed listening to Carol practicing her Appalachia Waltz Trio music backstage during breaks. She is always willing to share the latest ‘effects’ she’s working on.”