The audience was as much fun as the music (which was enormous fun), last night in the Presidential Ballroom of the Capital Hilton. In the course of a two-hour concert by the Beethoven Pops Orchestra, Richard Weilenmann conducting, members of the audience whistled, sang "Meow" in a well-coordinated chorus, chanted "Jingle Bells," clapped spontaneously in time to the music, and occasionally screamed in pure terror. A few got up to dance and some could be seen conducting to the sound of a different drummer. One or two, who were sitting near the percussion section, covered their ears at the climax of Ippolitov-Ivanov's "Caucasian Sketches."

The crowd stretched from wall to wall of the enormous room and spilled over into an anteroom. Adults sat quietly in chairs as concert audiences are supposed to do. But the children, hundreds of them, sat on the floor down front -- almost in the laps of the orchestra -- becoming closely involved in the music as children are supposed to do. A bust of Beethoven sat on a pedestal behind the podium, smiling enigmatically at the proceedings, as though he knew that there was nothing else in Washington quite like the children's concerts given in his name.

The music included Victor Herbert, Leroy Anderson, Leopold Mozart's "Toy Symphony" and big-band tunes from the '30s as well as an outrageous "Peter and the Wolf" with dancers in animal costumes miming the roles of the bird, duck, cat and wolf as well as dancers in human costumes playing Peter, his grandfather and the hunter. "Who's the good guy?" shouted narrator Dick Dyzel, alias Captain 20 of WDCA-TV. "Peter!" shouted back the audience, who had obviously done its homework and remained alert well past the normal bedtime hour.

One little boy was terrified at the entry of the cat (a very large cat, it should be noted) and began to cry, earning himself a seat on the capacious lap of host Maria Fisher until his mother came to get him. But others were able to handle the tension even when the wolf began his successful pursuit of the duck (who was dressed like Beatrix Potter's Jemima Puddleduck).

The chase veered across the packed ballroom and out a door just as the wolf was getting the bird -- then a flurry of feathers flew in the door, telling the sad story more eloquently than any words could. But it turned out well enough at the end. "Well," grumbled Grandfather in the rear guard of the triumphal procession to the zoo, "and if Peter hadn't caught the wolf--what then?" "But he did caught him," answered a little girl's voice from the front rows. He caught the audience, too.

Special mention should be given to the six anonymous soloists from the Landon School who did some virtuoso work on toy drum, kazoo, two kinds of bird call (cuckoo and generic), ratchet, triangle and slide whistle in the toy Symphony.