There will be two opportunities to hear Charles Rosen, author of the important The Classical Style. He will lecture on Thursday and perform on Friday. A particularly good chance to hear for free the Beethoven Diabelli Variations by an outstanding pianist.

One of the best things about Boston is hearing relatively little-known works. The New England Conservatory L'Heure Espagnol is the second production of the Ravel opera in three years (the other was by the Boston Summer Opera Theater). It has a brilliant orchestration; listen for the sarrusophone part!

PAINE HALL. Charles Rosen lecturing on "Romantic Theories of Expression and Schumann." Free. Thursday, February 7, 4:15 p.m.

BROWN HALL (New England Conservatory). Ravel: L'Heure Espagnol; and Purcell: Dido and Aeneas. Tickets: $5 (call: 536-2412). Thursday through Sunday, February 7-10, 8:30 p.m.

SANDERS THEATER. Charles Rosen, pianist, playing Beethoven: Diabelli Variations and Hammerklavier Sonata. Free (no tickets). Friday, February 8, 8:30 p.m.

CABOT LIVING ROOM. Music for Woodwind Ensembles by Mozart and Beethoven. Free. Saturday, February 9, 8:30 p.m.

DUNSTER LIBRARY. Brandenburg Party. Open sight-reading of Mozart: Piano Concerto No. 21 and Symphony No. 30; and Bach: Concerto for Two Violins. Bring your music stand. Sunday, February 10, 3 p.m.