This afternoon Convivium will sing a cappella music at St. George's Episcopal Church and Prince George's Opera will present its final performance of Rossini's "The Barber of Seville" at the Queen Anne auditorium of Prince George's Community College.

Pianist Daria Telizyn will play music by Barber, Tchaikovsky and Liszt this evening at the National Gallery.

Tuesday evening, the National Symphony Orchestra Youth Ensemble will feature cellist Rachel Young at the Kennedy Center Concert Hall. Also on Tuesday, the Library of Congress Summer Chamber Festival continues at Coolidge auditorium with works by Schumann, Hoiby, Shostakovich, Faure and Brahms and then on Friday with music of Mozart, Beethoven, Rochberg and Rossini.

Saturday evening, the National Orchestral Institute Philharmonic, conducted by Maximiano Valdes, will perform at the University of Maryland's Tawes Recital Hall. DANCE

Philadelphia's Terry Beck Troupe performs Beck's "Waiting Room" at Dance Place this evening. The Joffrey Ballet -- one of the nation's leading companies -- returns to Wolf Trap after a decade's hiatus with three programs Tuesday through Thursday evenings. Rima Faber, widely known in Washington as the founder-director of the elementary school dance troupe, the Primary Movers, has produced an evening of choreography for adults -- "The Longest Race" -- consisting of three works to be premiered by Faber and six dancers (including three children), with music by Teddy Klaus, at St. James Episcopal Church Saturday and Sunday. "Light From a New Torch -- Dancing to Vancouver" is an unusual touring project that began June 1 in Boston, is traveling to seven cities (including Washington, the second stop) and generating a dance work from a "seed" planted in Boston, with artists in each city adding to the final work. The last stop is Vancouver in conjunction with "Celebration '90: Gay Games III and Cultural Festival." The Washington installment takes place at Dance Place Saturday and Sunday evenings. POP MUSIC Tracy Chapman brings her acoustic intensity to the Post Pavilion Sunday, with the

lively South African pop of Johnny Clegg and Savuka opening.

Hotblooded flamenco-rock world-beat passion-music: It's the Gipsy Kings today at Constitution Hall.

Tuesday, the 9:30 hosts the Inspiral Carpets, who spurred a major war between record labels, and several of the top deejays from the legendary Hacienda! club.

Veteran boogie-bluesman John Lee Hooker won his first Grammy this year: He's at Wolf Trap Friday with John Mayall and his new-edition Blues Breakers.

John McCutcheon, Hazel Dickens and Sparky Ricker unite their spirits Friday night at First Congregational Church..