As the popular and classical musical cultures pull farther apart, crossing back and forth has become, for some reason, that much more intense. Bobby McFerrin -- the vocal explorer whose "Don't Worry, Be Happy" swept the nation in 1988 and buoyed (to Mr. McFerrin's displeasure) George Bush's Presidential campaign -- will set aside his four-octave singing range and arsenal of naturally produced sound effects for a while on Thursday to conduct the Beethoven Seventh Symphony and five other pieces.

Mr. McFerrin's foray into the jaws of the New Jersey Symphony at the Garden State Arts Center in Holmdel will include some familiar items by Bizet, Faure, Vivaldi and Bach. He will also do some of the improvisational singing for which he is best known.

There is a lot Mr. McFerrin does not know about conducting, and he says he is not afraid to ask. "If I want to get a certain sound from the orchestra," he said by phone from the Berkshires the other day, "I ask the concertmaster and he shows me how to do it. Sometimes musicians ask me questions I have to get translated. Jazz musicians just speak English to each other. I'm less used to this terminology."

"Remember, I only have one rehearsal for six pieces," he said. "One thing I have found out watching other people rehearse is that the less you say the better. You either do it with gesture or, better yet, you sing it the way you want it to sound. I'll get up there and see what happens. You never know. I believe in being prepared but not over-prepared." Separation of Traditions