AND now,'' says the announcer, ``Chick Corea!'' To a roar of applause, the tousle-haired pianist walks onto the stage alone, seats himself at the gleaming B"osendorfer concert grand, and plunges into a freely formed rendition of the jazz classic `` 'Round Midnight.''
But this afternoon Anthony Armando Corea -- performing artist, keyboard wizard, five-time Grammy Award winner, and perhaps the most highly regarded jazz composer in America -- is not here to play jazz. Nor is he here to play classical music -- although he played Mozart with the New Japan Orchestra in Tokyo in January and is to perform with the Philharmonia Virtuosi next February in New York.
Nor is his appearance at Berklee College of Music merely an old home week for this 1959 graduate of Chelsea (Mass.) High School -- who began the '60s playing with Herbie Mann, Stan Getz, and Miles Davis and ended that decade by recording his widely acclaimed album ``Now He Sings, Now He Sobs.''
Today, instead, Mr. Corea is playing the teacher -- and proving, in a two-hour question-and-answer session before a packed concert hall of student musicians, that he is one of the jazz world's most thoughtful and lucid champions.
``Don't improvise on endlessly,'' he begins with a smile, turning sideways on the piano bench and picking up the microphone after bringing his opening number to its conclusion.
It's a quotation from a typed handout the students have picked up at the door, labeled ``Cheap but good advice for playing music in a group.'' Some of this other tips: ``Play only what you hear,'' ``Play to make the other musicians sound good,'' and ``Leave space -- create space -- intentionally create places where you don't play.''
Then, with the natural ease of someone talking among friends, he launches into his subject.
What matters, he tells this energetic and musically sophisticated crowd of aspiring jazz and rock musicians, is ``your own certainty of what you like, and how that fits into things.
``We have the freedom,'' he explains, ``the inalienable right to do things as [we] see fit, to do them artistically, musically.'' Technique, he insists, is not the most important matter: ``You all know how to get a technique together -- you just get it together.'' The crucial thing, he explains, is to ``decide what technique to get together, and when.''
Lest that sound like a formula for looseness and uncontrolled spontaneity, however, Corea is quick to emphasize the other side of jazz: the need for discipline.
That sense of discipline, says composer Ted Pease, chairman of the college's professional writing department, is evident in Corea's entire outlook. ``He follows through with such tenacity and discipline every musical undertaking,'' he says. What impresses Mr. Pease most is ``what a good role model he is for young musicians.''
Can a successful music career be combined with family life, he is asked? Corea, the father of two grown children (his second wife, singer Gayle Moran, is in the audience with his parents), insists that it can. ``Family is a part of life,'' he says, and life would be diminished without it. ``I've learned to more and more really enjoy having a feeling of home,'' he says.
But the heart of the discussion lies in his music -- not surprisingly, since as vibraphonist Gary Burton says, ``He's the most prolific and versatile musician in our business.'' Mr. Burton, a faculty member at Berklee who has played and recorded with Corea for 12 years, says Corea has already written between 300 and 400 compositions. ``The only guy I know who was as productive was Duke Ellington,'' he adds, who in a lifetime wrote some 1,500 pieces.
Several of Corea's pieces, in fact, were specially written for his four-day mid-March stint at Berklee -- where, in addition to visiting classes, Corea spent his evenings preparing student groups for a concert of his music. ``He doesn't just rehearse them,'' says Burton. ``He teaches them how to think. He's intuitively wonderful at that.''
Burton, who planned the Berklee visit after Corea suggested it during a concert tour they had in Puerto Rico six months ago, says it is the first time the college has held such an extensive in-residence program -- and the first time Corea has put that kind of effort into teaching.
In an interview after his session with the students, Corea, dressed informally in open-necked shirt, gray slacks, and white running shoes, touches on his concern with the present tendencies in popular music.
``There is no direction -- it's obvious'' he says. ``I feel there are fewer healthy things about [contemporary music] than there are unhealthy things about it,'' he adds. ``What the masses end up with is a quality that gradually seems to degrade.'' That, in part, has motivated his reawakened interest in Bach and Mozart, whom he calls ``very stabilizing points.''
Another ``stable point,'' he says, is his own ``ultra-conservative mode of apparel.'' ``I used to dress kind of wild,'' says the now-clean-shaven Corea, recalling his days of loud print shirts and headbands. Now, as he watches the audiences in his concerts here and overseas, he says that ``one of my greatest joys is seeing some young guy in a new-wave mock-up sitting next to some 50-year-old.''
One modern tendency that pleases him is the shift away from drugs and alcohol among jazz musicians -- who, he says, are ``swinging very quickly over to health consciousness from the exact opposite, which was drugs and low life and promiscuity.''
And that relates, obviously, to his feelings about the family. The notion that real artists must forgo family life is, he snorts, ``such a psychological bunch of hogwash -- so counterlife, so counterproductive.''
His wife agrees. ``We've really worked very hard at our relationship,'' she says gently, noting that her husband, even when not on the road, sometimes ``locks himself up in his room for three or four days'' to compose, with only ``little breaks to eat.''
How does she view that? ``First of all, I think it takes real support of what the artist is trying to do, rather than resistance,'' she says. ``Fortunately, I love his music -- I want other people to hear it.''
She speaks of the ``quality time'' they share, and their insistence on doing something together at least once a week. ``I just don't think it's the amount of hours that matters -- you can be close to someone without being next to them all the time.''
Asked by the students about his future, Corea notes that ``this year's project'' is the formation of his ``electric band.'' (He has recently added a well-equipped electronic studio to his home in Hollywood, Calif., and he performed on a portable synthesizer at the Berklee concert.) He also hopes to make a record with Gayle Moran. Over the longer term, he plans to focus on his interest in orchestral composition, adding to a growing list of chamber works, which, critics say, show the influences of Bartok, Scriabin, Gabriel Faur'e, and Darius Milhaud.
And why does he do it all? ``My strongest motivation,'' he says with a slight grin, ``is that I just love to do it.'' He aims, he says, at ``enlivening the audience, enriching them, not making them hysterical or confusing them.''