Modern music concerts show commitment to all tastes. More contemporary works heard in city than usual. NEW YORK FESTIVAL

The First New York International Festival of the Arts is now fully under way. This month-long, ultra-ambitious venture is billed as an exploration of the 20th century and encompasses all the performing arts with the arguable exception of opera.

During the first six nights, I sat in on all, or part, of eight concerts, and had to omit an equal number of others that were of comparable interest. In other words, in terms of music there is throughout the festival more than any one person could hope to take in, and it appeals to the broadest possible tastes.

The official music opening night occurred at the New York Philharmonic, under the baton of music director Zubin Mehta. The program was not startlingly original - Bartok's Second Violin Concerto with Itzhak Perlman the soloist, Stravinsky's often-heard ``Le Sacre du printemps,'' and the New York premi`ere of Ellen Taaffe Zwilich's ``Symbolon,'' written for the orchestra's recent Soviet tour, and given its world premi`ere performances in Leningrad and then in Moscow at the beginning of the month. The ``Sacre'' had a barbaric splendor to it, and the Zwilich was a brief but assured study in the exploitation of a full symphony orchestra.

Some of the most prestigious names in concert music today - the Juilliard Quartet, Pierre Boulez and the Ensemble Intercontemporain of Paris, the Russian maestro Yuri Temirkanov and the Philadelphia Orchestra - were involved these opening days, with more to come.

The advantage of this generally conservatively programmed festival is that unique things happen. For instance, I doubt the Juilliard would have paired quartets by Gunther Schuller and Milton Babbitt on the first half of their 92nd Street Y program. And surely the New York Philharmonic would have been terrified to program Luciano Berio's 50-minute-plus ``Sinfonia'' and Boulez's ``Notations'' on a Boulez-led program, had it been for the regular subscription audience.

``Sinfonia,'' an oddly unengaging total of five often-dazzling sections, received a stunning performance under Boulez, with the aid of the New Swingle Singers. I have never heard the piece more brilliantly performed. The Philharmonic responded to every one of Boulez's multiple tempo variations with unanimity and managed even the most devilishly virtuosic passages with excitement and facility.

As for the aforementioned quartets, the Schuller proved to be the most engrossing and affecting - combining serial techniques so popular at the time of its composition (1958) with an acute feel for the emotional possibilities of timbral blends and sharp rhythmic variations. Babbitt's exertion proved no less engrossing, though rather less fulfilling in terms of emotional response.

This is not to say that music must always communicate passion, as Boulez's ground-breaking piece ``Le marteau sans ma^itre'' proved yet again in a composer-led performance with his Ensemble Intercontemporain at the Museum of Modern Art. ``Marteau'' is, in fact, devoid of sensuous or passionate overtones. There is an overriding scrupulous intellect at work at all times, and yet such is the nature of this particular musical mind that all the rigid serial structuring and attempts at forcing music in a new direction cannot hide a vivid timbral world of spellbinding effectiveness and intensity.

How interesting to encounter the mellow Boulez of ``Notations'' just a few nights later at the Philharmonic. His melodic muse has mellowed to something kaleidoscopically glistening, even lush, and his use of orchestra puts one consistently in mind of his early teacher Olivier Messiaen. In general, if one could lament the lost opportunities to do more of these sorts of vivid explorations, one nevertheless cannot help feeling that New York is still hearing more contemporary music under unusual circumstances than it does in the course of the regular musical season.

Not all concerts have drawn equally well at the box office. The Chamber Music Society of Lincoln Center offered a committed, exciting performance of Bartok's Sonata for Two Pianos and Percussion to a two-thirds-empty Alice Tully Hall. The aforementioned Juilliard concert was equally sparsely attended. The Philadelphia Orchestra's two concerts were sell-outs, what with their mix of music. Even so, maestro Temirkanov's way with Rachmaninoff's ``Symphonic Dances'' and Sibelius's Fifth Symphony was bracing, richly shaded, and superbly dramatic. The Philadelphia played for him with particular gusto.

The same can be said for the Philharmonic's response to Boulez throughout his evening: The orchestra was clearly delighted to have its former music director back on the podium. And who could resist Alexander Toradze's astonishing account of Prokofiev's hair-raisingly difficult Second Piano Concerto? It was the stuff of legends, and the Philharmonic, under assistant conductor Felix Kruglikov, responded impressively.

Clearly, there is a commitment to musicmaking in all venues that is not ``situation normal'' for this musically glutted city. It remains to be seen how well standards hold up through July 11 (when Pl'acido Domingo gives a free outdoor recital in Central Park). But as things look now, there is at least a spark to this festival that makes it noteworthy.