Via telephone I have tracked John Harbison to Italy, one of the several pockets of isolation he resorts to when the composition bug bites.

That's quite a lot these days, thanks in part to his pocketing last year's Pulitzer Prize in music. The trip that brings him home, for example, for concerts this week with the Utah Symphony - Friday and Saturday in Symphony Hall - likewise takes him to Washington the following week for the premiere of his Fantasy Duo for Violin and Piano at the Library of Congress. His Foxtrot for Orchestra, "Remembering Gatsby," will then get an airing by the Philadelphia Orchestra under Hans Vonk. After which, following another Mediterranean sojourn, he returns in the spring for the premiere of a song cycle written for soprano Dawn Upshaw and pianist James Levine."There were more commissions," the 49-year-old Harbison says of his Pulitzer award and its effect on his life, "except at that point I already had all the work I could do and wasn't really able to respond." What it did do was extend his reputation beyond the musical community, "so that I found myself hearing from people I had gone to high school with or who had known my father in the 1930s."

In short, a composer who had already earned himself a prominent place in our concert halls found himself something of a celebrity - a big jump for a young man whose teacher at Harvard, the redoubtable Walter Piston, tried to warn him off a serious-music career altogether.

"He said I was born to be a pop or musical-theater composer," Harbison, himself a former jazz pianist, recalls. "And in a way I wish he'd been right. If I'd had the success as a pop composer I've had as a concert-music composer, I wouldn't have to teach at MIT and could be living in the Hollywood hills. But I think you have to write whatever you're best at, and I simply wasn't as good at that as at the stuff I do write."

What Harbison writes is music of a strong organizational sense that, in the words of one critic, "represents a bridge between postwar formalism and the new conservatism of the past decade." Others have labeled him "the flagship composer of the New Romanticism" - an extreme view perhaps, given the Stravinskian severity of some of his output, but a reflection of its comparative accessibility.

The piece he will be conducting here, for example, his Violin Concerto (with Joseph Silverstein as soloist), he describes as stemming from "the most classical period in my development." Written for his violinist wife, Rose Mary, its formal interest for him, he says, "was the return of the various subjects and themes in anything but their original order." Yet on the occasion of its premiere, in 1981, one reviewer called attention to its "wide emotional range, from the passionate and rhapsodic singing of the first movement to the exuberant country fiddling of the finale."

That's a long way from the mathematical exercises cooked up by Milton Babbitt at Princeton, where Harbison's father taught and where he himself returned for graduate study with Roger Sessions. Harbison acknowledges that the kind of music he is finding success with these days would hardly have been fashionable a generation before.

"I think that is probably an acknowledgment that the American orchestral repertoire had gone into a period of hibernation, especially in the '60s and '70s," he says, "and that very direct and bold measures were needed to bring it back." Now, by contrast, he believes that more and more composers are writing with what he calls "a sense of an audience" and a sense of the orchestra.

"You think about it and you realize that there were so few opportunities for so many years that many composers never developed a real orchestral technique. The result was a number of distinguished composers who, for really quite practical reasons, became chamber composers. For instance, I came up in a period when writing an orchestral piece was almost a complete indulgence because there was almost no chance anyone would polay it. I didn't write one until my opera, 'Winter's Tale,' when I was 33."

Since then he has gone on to not only write for the orchestra _ his Symphony No. 2 was premiered last year in San Francisco _ but advise them, beginning with his appointment as composer-in-residence with the Pittsburgh Symphony in 1982. That lasted until 1984, after which he followed music director Andre Previn to Los Angeles to assume a similar position with the L.A. Philharmonic, serving as new-music adviser through the 1987-88 season.

"I think I was the only composer in that first group of Meet the Composer residencies who didn't know the conductor beforehand," Harbison says of his association with Previn. "But that turned out to be no problem. In fact both of us expected to be around Pittsburgh longer than we were, so I was especially glad to be able to continue in Los Angeles because we had a lot of projects we were able to complete. Also, L.A. has this unique New Music Group within the orchestra, and it was marvelous to be associated with that."

Harbison is no stranger to conducting on other fronts either. Next year he is scheduled to tour with the Chorus and Orchestra of Boston's Emanuel Church, with whom he has been associated for many years. For seven years he served as music director of the Cantata Singers, performing the music of Bach and Schuetz, and since 1984 has been co-director of the new-music ensemble Collage. It is no accident, therefore, that the work that won him the Pulitzer is itself a cantata, "The Flight Into Egypt."

In fact this awareness of the past has led some critics, myself included, to complain of a certain self-consciousness in much of Harbison's music, a sense that somehow history is looking over his shoulder as he martials his ideas for their place in music's great march of time.

"I wouldn't say it's self-conscious," he says in his own defense, "but it is conscious. I want to thrust the listener into the whole maelstrom of tradition, or at least my definition of it _ I don't want there to be any escape from that. But I don't feel haunted at all by that; it's just the way I like to compose.

"Actually," he adds, "I've been amused at the way, as my pieces stay around for a while, the references they seem to call up seem to change. For example, when my chamber opera, `Full Moon in March,' came out people were reminded of all kinds of things, some of which I'd not heard, things like Britten and Janacek. Recently the piece was performed again and this time the commentary focused on other composers, like Tippett and Sessions. It must be the power of suggestion."

Whatever the case, Utah Symphony patrons will be able to draw their own conclusions Friday and Saturday as Harbison's music is performed in about as traditional a context as possible _ i.e., bracketed by music of Haydn and Beethoven, the Symphony No. 99 and Symphony No. 5 respectively. Those will be conducted by Silverstein.

Starting time is 8 p.m., with a pre-concert lecture each evening at 7:15. In addition the same program can be heard in a Finishing Touches dress rehearsal Friday at 11 a.m., following refreshments in the lobby at 10:15 (tickets $5).

Tickets to the evening concerts range in price from $9 to $27. For information call 533-6407.

quite practical reasons, became chamber composers. For instance, I came up in a period when writing an orchestral piece was almost a complete indulgence because there was almost no chance anyone would play it. I didn't write one until my opera, `Winter's Tale,' when I was 33."