The Harvard-Radcliffe Orchestra opens its '75-76 season this Friday night. Judging from rumors emanating from HRO members and affilliates, it might be well worth interrupting your masked Halloween ball for a couple of hours of uplifting spirits in Sanders Theater. The orchestra is bigger and possibly better than last year, and the tasteful programming should appeal to a wider variety of listeners than it has in the past.

To the tune of the bicentennial, the orchestra will open with a performance of Appalachian Spring, a suite from the Pulitzer prize-winning ballet by prominent American composer Aaron Copland. The ballet is a charming work which captures all of the joyful and apprehensive emotions of a young pioneer farmer and his bride-to-be in the Pennsylvania hills during the early part of the last century. The flavor of the mountain folk tradition is so pungent that one is nearly drawn to begin foot-stomping and hand-clapping.

Rounding out the program will be a work composed in 1960 by Penderecki called Threnody For The Victims Of Hiroshima and Brahms's Symphony No. 2

FRIDAY

Harvard-Radcliffe Orchestra performs works of Brahms, Copland, and Penderecki. Tickets $2.00 ($1.50 for students) at Holyoke Center Ticket Office or at the door. Sanders, 8:30.

Stephen Drury '77, piano, and Diane Schutz, violin, performing Brahms's Sonata in G Major for violin and piano and Schumann's Symphonic Etudes. Dunster Library, 5:30.

Apple Hill Chamber Players play works of Bach, Mozart, Schumann, and Stephen Foster. Tickets ($2.50 for students) available at door. Longy School, 8:00.

SATURDAY

Jay Golan '77, trumpet, John Hulling trombone, Adrian Graham, French horn and Christopher Wilkins '78, piano, play Hindemith, Poulenc, Josquin and Beethoven. Dunster Library, 8:00.

SUNDAY

Choral sight reading of Bach's b minor Mass. F. John Adams, conductor. Leverett Junior Common Room, 4 p.m.

Pamela Barr, cello, and Randall Hodgkinson, piano, play Bach, Beethoven, Boccherini, Haydn. Ellot Library, 8 p.m.

Rondo String Quartet performs in Homes Hall Living Room, North Houses, 8:00 p.m.

TUESDAY

Lou Arnold, guitar, and Wendy Gardner, flute. Senior Common Room, Currier House, 8:30 p.m.

WEDNESDAY

Zagreb Proarte String Quartet performs in Sanders Theatre, 8:30.