The audience at Sanders Theatre Friday night heard the best music that's been played at Harvard all year, and they probably had more fun than anyone else in Cambridge. The HRO concert was more than music--it was sheer delight.

The program began with Mozart's Haffner Symphony. In previous concerts the HRO has played Mozart without adequate discipline, but Friday night they displayed complete mastery. The violins were unexpectedly precise, despite difficult sections of trills and runs. The orchestra did not sacrifice emotional force for precision, however, and the trio of the third movement was interpreted almost romantically. The controlled performance of the finale added to its excitement.

The HRO next performed the world premiere of conductor James Yannatos' Prieres dans L'Arche, a setting of four poems by Carmen Bernos de Gasztold, scored for a small orchestra and soprano. In each poem an animal characterizes himself in a prayer ending with "Ainsi soit-il." Yannatos does not portray the animals, but the attitudes they represent. The animals' feelings are summarized by their way of saying amen, and the score provides the interpretation which the printed page leaves to the reader. For instance, the cat, aided by a marvellously meowing orchestra, says amen in smug anticipation of God's curse on the race of dogs.

Yannatos' score, especially as interpreted by soprano Chloe Owen, exhibits perfect understanding of every line of the poem and an ability to transform this understanding into music. The audience stopped looking at the translation of the text during the first poem, but it continued to respond, with comprehension and laughter, to the music itself. The work is humorously, but thoughtfully, refreshing.

Miss. Owen's musical personality, expressed with restraint in the Yannatos work, blossomed in the Verdi Bolero, "Merce dilette, amiche." She sang the aria with perfect intonation and virtuosity, and the audience demanded that she repeat it. The second time around, Miss Owen was every inch the soprano. Flowers in hand, she sang to the audience, to the orchestra, to Yannatos and, quite possibly, to Verdi himself. She was obviously enjoying herself and her joy was contagious.

But in the second half of the program the HRO, Yannatos, and Miss Owen proved that they could do more than entertain. They played Mahler's Fourth Symphony--a technically demanding, emotionally difficult work. The first movement was characterized by the precisely drawn contrast between the rich, sweeping romanticism of the strings and the sharp clarity of the brass and woodwinds. The orchestra demonstrated perfect control in responding to Yannatos' variation of tempo and dynamics.

In the second movement, the woodwind solos were outstanding, but the French horns stole the show. Their usual difficulties with intonation and entrances disappeared, and they played in tune, in time, and in tone.

But even if the orchestra had played only the third movement, the concert would have been the finest the HRO has given this season. The movement is incredibly sensual, and the intensity of Yannatos' interpretation enhanced this quality. The melody, introduced by the celli, is first picked up by the rest of the strings, and finally by the oboe and the rest of the orchestra. The tension builds slowly with only momentary relief, until the audience almost aches for it to end. But it continues until the trumpets recall the melody of the first movement at the climax, and the violins harp, and woodwinds end it, sweetly satisfied.

In the fourth movement, Miss Owen joined the orchestra. Her performance alternated between the restrained sweetness and relaxed gaiety that the score demands. The lyrics are meant to express the plenty of Heaven, and operatic flourishes would be completely inappropriate. Miss Owen abandoned her Verdian fire-works and sang with pure, sweet joy.

The enthusiastic reception which the audience gave the orchestra was rivalled only by the HRO's obvious adoration of its new conductor. If it is this rapport which has brought the orchestra to its present level of accomplishment, then no one should miss a concert as long as the HRO is led by Dr. Yannatos.