Is Beethoven still Beethoven after all these these years?

Roll over, Beethoven. Here come Barry Cooper and the ingenuity of musical scholarship which have ``realized'' your intention of writing a 10th Symphony.

No matter that it's 161 years later. Or that skeptics say it's impossible to write music posthumously. Or that your Ninth Symphony can't be surpassed.

The first movement of the 10th Symphony will have its world premiere tonight in London's Royal Festival Hall by the Royal Liverpool Philharmonic, under the sponsorship of EMI Classics. It will be performed in the United States this Sunday in New York's Carnegie Hall by the American Symphony Orchestra.

A compact disc recording by the London Symphony Orchestra, directed by Wyn Morris, will be released this week by Pickwick International, a London recording company.

The musical score is copyrighted by Dr. Cooper, a professor of music from Aberdeen University in Scotland. It announces that the music is by Ludwig van Beethoven and has been ``realized and completed'' by Cooper.

Is Cooper playing a joke on the London Philharmonic Society, which commissioned two symphonies from the German-born composer but received only one, the Ninth? Where did the 10th come from? The simple answer is that Cooper's construction of the first movement of Beethoven's 10th was painstakingly developed during five years of musical detective work. A scholar who has studied Beethoven's musical sketches for many years, Cooper is confident he has identified, among some 8,000 pages of sketches, those fragments belonging to the 10th.

``There's a large amount of unidentified sketches in Beethoven's sketchbooks, and the difficulty is to work out which of these various unidentified fragments might belong to the 10th Symphony,'' Cooper told the Monitor.

Beethoven scholars have reserved judgment on Cooper's work, waiting to hear the results and to learn more about how Cooper pieced together and developed the musical ideas. Scholars say fragments from many symphonies can be found in Beethoven's sketchbooks, though they never became completed works. Some say the 10th was never more than a hopeful intention.

But in the London academic journal Music and Letters, Cooper wrote three years ago that all reasonable doubts about Beethoven's 10th had been dispelled. He cited a letter dictated eight days before the composer's death in 1827 promising the Philharmonic Society that a new symphony ``lies already sketched in my desk.'' The society had commissioned the Ninth, which was completed in 1824, and had sent a check for 100 to cover his expenses while Beethoven was working on the 10th.

Cooper also cites a firsthand account by Karl Holz, a companion of Beethoven, who described the first movement of the 10th which Beethoven once played for him on the piano. Holz's description supposedly fits the material that Cooper said he and a curator of the Beethoven archives in Bonn found among the sketches.

Wyn Morris directed the London Symphony in the first recording of the Beethoven/Cooper composition, which takes nearly 20 minutes to perform. He says he found ``great beauty'' in the opening section of the piece.

``The themes are obviously very, very interesting,'' he told the Monitor. ``One cannot predict what Beethoven himself would have done. [But] technically it is written in the style of Beethoven. You can't fault it.''

When the news was out that Cooper had developed the structure for a part of the 10th, there was a scramble for performance and recording rights. The publicity has catapulted this little-known scholar to worldwide fame and possible fortune.

Cooper said there are many technical problems in reading Beethoven's sloppy musical jottings and piecing together scattered pages from his sketches.

The sketchbooks were cannibalized after Beethoven's death and pages were sold as souvenirs of his handwriting. They weren't recollected until the late 19th century, often with pages missing.

``In the development section, a lot of which Beethoven apparently didn't sketch, I've taken the themes from the exposition which he did write and developed those in the way he would have done,'' Cooper said. ``Obviously, it's not exactly the same way as he did, but I think it gives a rough idea.''

``Eventually, I found it was possible to complete the movement by developing his own themes without actually inventing important new themes of my own.''

Scholars say Beethoven typically revised his music until a piece was published. Cooper agrees, and he says that as a scholar he developed from the sketches ``an impression of the symphony he had in mind at the time rather than what it might have turned out to be later on.'' Sketches from the 10th, Cooper said, date from 1818 to 1827.

A unique feature of the 10th is the change in key from a slow introduction in E-flat major to an Allegro section in C minor, something Beethoven had never done before in a symphony. The musical ideas, however, are more typical of Beethoven's middle period than his later compositions, according to Cooper.

Director Wyn said this was the result of Cooper's method of making the development of themes as idiomatically like Beethoven as possible. If the 19th-century composer himself had completed the development, Mr. Wyn said, he ``would have taken more steps in the dark.''

``It's so much more convincing to hear the tunes and harmonies that Beethoven left behind played by a first-class orchestra like the London Symphony than seeing a few sketches on a page,'' Wyn said.

``The harmonies are all `Beethovenien' and altogether well worth listening to and worth conducting. And it pleased my bank manager to no end!'' said the Welsh conductor, who also stands to profit from the recording.

Paulette Kernis of MonitoRadio's London bureau contributed to this story.