You have just two chances left to hear the chorus of the Orchestre de Paris, which is the most extraordinary aspect of the orchestral concerts now being given in the Kennedy Center's French Festival. Tonight they sing in Berlioz' "Romeo et Juliette," and tomorrow night in his Requiem.

Last night there they were once again, singing their national anthem and ours, and again, their sounds in "La Marseillaise" were on the hair-raising side. After that, anything else was a bonus. There is no guarantee that they will repeat the anthems each night, but it appears likely.

Their chorus master, Arthur Oldham, took a bow last night as he should. He is one of the finest men in the field. Once the two anthems were over, the chorus drew in its more stentorian sounds, offering instead smoothly polished, exquisitely worded singing of the "Meditation Religieuse" and "Death of Ophelia," the first two parts of the three unrelated works Berlioz put together, calling them all "Tristia." The third, too, requires the chorus, but offstage and wordless, in a lament on "an."

All three episodes evoke elegiac shades in differing aspects. Their changing orchestration is unmistakable Berlioz: ich, though softly hued.

Daniel Barenboim conducted them handily, at times eloquently, but rarely with the penetration that made their grief seem real. The third, a Funeral March for Hamlet, was paced a touch too fast for its best effect and the chorus at first was too loud. Most strange of all was Barenboim's own firing off a pistol where both Berlioz and Shakespeare call for distant shooting.

The Fantastic Symphony closed the evening in a reading that at times recalled Charles Munch, this orchestra's first great conductor, who died in Richmond, Va., while on tour with the musicians. Once the opening movement was over, Barenboim and the orchestra were immensely impressive. At first, however, he took a breakneck pace, losing both essential details and precision in the process. Munch, too, took the music very rapidly, but he created tension with the speed. With Barenboim the feeling was almost entirely one of undue haste.

Many in the audience last night asked why so many seats were empty. The answer may behigh prices of the tickets and the fact that the Fantastic Symphony was heard in that hall rather recently. Tonight's "Romeo," however, comes infrequently to any hall.