HE MAKES IT UP AS HE PLAYS ALONG

There’s a scene in “Amadeus” that is as revealing about musical gamesmanship of that era as it is about its two protagonists.

Salieri had just composed a homely little march in honor of young Mozart’s arrival in court. Modestly, the precocious composer sits at the keyboard, repeats Salieri’s march verbatim, then merrily dissects it, expands it and, to the amazement of all, winds up with a whole new tune--later to turn up in “Le Nozze di Figaro.”

The incident may be apocryphal, but, according to pianist Richard Grayson, such improvising on others’ themes not only was common in the 18th Century but even continues to the present.

Grayson should know. Among non-jazz improvisers today, he is reportedly one of the best, as will no doubt be revealed when he presents his 16th annual Classical Keyboard Improvisation Concert on Friday at Occidental College.

“I’m really an exponent of an older art,” Grayson, 43, commented during an interview at his Santa Monica home. “Composers in the past were always improvising on tunes from operas or whatever. Of course, they all improvised in their own style.”

The scene at Thorne Hall on Friday night will not hark back to the ad-lib performances of the past. For one thing, the second half is all-electronic (this year, consisting of Grayson’s tributes to Handel and Bach). And in the opening improvised portion, he will follow a different path from his forebears.

It all goes something like this: Someone in the audience suggests a tune, “The Shadow of Your Smile,” for example. Others will call out composers’ names.

After a brief moment of concentration, Grayson will produce that tune as Debussy or Bach or Mahler might have arranged it.

“I really do this for my own pleasure,” the self-effacing musician admitted. “I’ve always had this need to do improvisation.”

While denying he is a cult figure at Occidental--where he has taught for more than 15 years--Grayson did acknowledge that “a certain raucousness can occur” at his eagerly awaited concerts.

“I open myself to different, even ridiculous, choices,” he said. “But I’m not out there to make musical jokes. If I did that all the time, I would find it depressing.”

Grayson dismissed a comparison with the likes of Liberace, who elicits whoops from his audiences with similar musical games. “I like to think that the level of musicality is higher,” he said. “I aim for an intense listening experience.”

He recalled that at his Occidental concert last year, someone suggested “Mission: Impossible” played in the style of Haydn. “That one worked real well. But another request was for Bach’s ‘St. Matthew’s Passion’ overture a la Duke Ellington. I refused.

“I will not cheapen the music that way.”

How does he do it? Compulsively, Grayson trotted over to the piano. “You know this march, from Handel’s ‘Judas Maccabaeus’? If I were to do it in the manner of Brahms, for instance, I’d think of a piece similar in structure, like this”--Grayson played one of Brahms’ lilting rhapsodies.

“Before I start to play, I’m matching what I need to do with what I already know. If I can find an idea before I start to play, it usually works out fine.”

He faced the keyboard and combined the Handel tune with Brahms’ peculiar harmonies and accompanimental style.

Preparation for the concert must be intense, right? “I still only practice about a half-hour each day,” he said with a smile. “I don’t know what will happen this Friday. It’s in the hands of the gods.”