— BIRMINGHAMThe arrival of a new music director is, by tradition, the occasion for an evening of cautious magnificence — a Mahler symphony, perhaps, or a Brahms concerto, the kind of programme designed to flatter the orchestra without testing the new partnership. Thursday evening's debut at Symphony Hall offered no such reassurance, and was the better for it.

The programme opened with a brief contemporary commission, a fifteen-minute work for full orchestra and amplified violin titled "The Broken String," by a composer in her early thirties whose name had, until last week, been familiar only to specialists. It is not, in any conventional sense, a curtain-raiser; it is a work of restless intelligence, structured around a single broken phrase that ricochets through the orchestra in fragments before being, in the final two minutes, only partially reassembled. It is the kind of piece that asks a great deal of an ensemble — and was here delivered with a clarity that suggested unusual rehearsal commitment.

What followed, after the interval, was a Sibelius symphony of bracing severity. The new director's reading was leaner than the orchestra's traditional approach, with sharper attacks in the strings, more transparent textures from the woodwinds, and a refusal to indulge in the lush orchestral plush that Birmingham audiences have, over the years, come to expect. Reactions in the bar at the interval were divided. Reactions at the close of the symphony were not.

It is a performance one wants to hear again. The programme will be repeated on Saturday and broadcast next month.