Improvisation is a trademark of rock and jazz shows, but at symphony orchestra concerts, it's as rare as a Mozart autograph. That's too bad, argues pianist Robert Levin, because improvisation played a significant part in Mozart's performance practice -- not to mention classical music before and after the composer's time -- into the 19th century. It was a regular characteristic of classical music for longer than it wasn't.
When Mr. Levin performs Mozart's Piano Concerto No. 20 with the Pittsburgh Symphony Orchestra this weekend, he'll make up much of the music on the spot, including embellishments and two cadenzas. The Mozart scholar also wouldn't mind if audience members clapped while he played.
"It's fine with me. Maestro [Manfred] Honeck is going to have to decide if he encourages that or not," said Mr. Levin. Applause was something that Mozart himself expected and even relished during the public premiere of his "Paris" Symphony -- not after the piece, not between its movements, but during it.
The piano concerto is one of the pieces featured in the PSO's Mozart Festival, which explores the composer's vast oeuvre in two programs led by Mr. Honeck and one chamber music concert.
The first weekend features instrumental and symphonic repertoire: "Eine kleine Nachtmusik" ("A Little Night Music"); the piano concerto with Mr. Levin; Horn Concerto No. 1 with PSO principal horn Bill Caballero; and Symphony No. 41 ("Jupiter"). Following his performance, Mr. Levin will play additional improvisations in the style of Mozart.
"The idea is to prompt the audience to write two bars, just a little snippet of music, that is in the classical idiom, so that it works for the process I have in mind," said Mr. Levin, who is retiring this year from the faculty of Harvard University.
In his opinion, improvisation is "a very risky enterprise," but it adds drama and spontaneity to performances that, in modern times, have become safe and formulaic.
"Listening to jazz greats improvise on a standard tune is not so different from Mozart's improvising variations on a well-known melody of his time. The style may be different, but the principle is not terribly different."
Mr. Levin also has written a new edition of the First Horn Concerto, performed by Mr. Caballero, based on Mozart's two versions. The composer died before completing the work.
The first version demands a range of more than two octaves; Mozart worked on the later version when he realized the aging horn player for whom he wrote it, Joseph Leutgeb, was losing his teeth and his lung power. This easier version has a smaller range (a ninth), a more pronounced orchestral part and longer rests for the soloist.
Mr. Caballero chose the one "with teeth," he joked.
"If I did the other version, I'd be getting overpaid by the note," he said.
Mr. Levin's completion of the harder version includes changes to the end of the first movement and a small development section in the rondo. Mr. Caballero will also select from three short cadenzas, although he said he'd wait to meet with Mr. Levin before choosing.
The horn player also is looking forward to working with Mr. Honeck, a native of Mozart's Austria, to shape the interpretation. With Mozart, the PSO's music director said he aims for "pureness" above all, whether in intonation, rhythm or sense of phrasing. Vibrato must be deployed "with taste" -- it should be less pronounced than in typical Romantic performance but still meet the emotional expectations of a modern audience.
"In Mozart's music, you are not allowed as an artist ... to put some unclean, [impure] elements in it," Mr. Honeck said. The demand for transparency is one reason why the PSO asks for a Mozart concerto during most auditions.
If, after this weekend, you're still craving more Mozart, Mr. Levin will join PSO musicians Tuesday in a chamber music concert co-presented by Chamber Music Pittsburgh. The performance includes fragments completed by Mr. Levin. It also features violinist Noah Bendix-Balgley, clarinetist Michael Rusinek, violist Meng Wang, cellist Anne Martindale Williams and violinist Christopher Wu.
Next weekend, the orchestra, soprano Sunhae Im, baritone Lucas Meachem and the Mendelssohn Choir of Pittsburgh will perform selections from several Mozart operas and sacred works. Host Don Marinelli, a former professor of drama at Carnegie Mellon University, will take on multiple characters -- from Leopold Mozart to Holy Roman Emperor Joseph II -- to connect various pieces of the program.
Together, these elements will "bring closer the composer and human Mozart to the audience," Mr. Honeck said. "That's the goal of having a festival."