Barbad Nassirian, a young santur (Persian dulcimer) virtuoso with a distinctively percussive attack, weaves a filigree of improvisation around a simple melodic frame. The audience for this Iran Quake Relief Committee benefit concert Saturday at Fairfax High School listened intently to a lengthy, complicated section chock-full of expansions and repetitions. Since the santur has no dampening devices, these florid improvisations merged into a delicate, dazzling pattern akin to the etchings around the entrance to a mosque.

Suddenly Nassirian would hit a major triad -- a jarring conclusion to the microtonal mesh. Then the strings and woodwinds surrounding him -- led by conductor-arranger Golnoush Khaleghi -- drove home a Western-style cadence.

The Khaleghi family (including Golnoush's late father, Rouhollah Khaleghi, the orchestra's founder) counts itself among the many Iranians who have been attracted to the Western musical ideas. Golnoush Khaleghi's success in grafting features of Western counterpoint and orchestration onto Persian forms was no easy victory. Such victory came about only when Western phrasing and harmonies served the quiet mystique of a Persian tune, rather than vice versa. The first of the three orchestrated pieces, Hossein Dehlavi's "Shur-Afarin," illustrated this imbalance.

The musical differences dividing both cultures surfaced in the program's first half, devoted to improvisatory Persian forms. Persian music's roots are lyrical, not dramatic. When vocalist Jamshid Zarringhalam sang verses from Hafez, a 14th-century mystic, the poetry's meter imparted the recurrent rhythmic structure to tar (lute) player Nader Majd's improvisations. This music seems innately opposed to the large blocks of harmony favored by Western orchestrators. It values the tiniest detail. Violinist Arsalan Hamidi, whose relaxed bow generated hollow, muffled tones, showed how a singular drone could enrich his material in a seemingly infinite way.