What better way could there be to spend a sultry summer Sunday afternoon than by opening your chambers to the strains of chamber music performed live by five Washington ensembles in the studios of WAMU-FM (88.5 MHz), American University's public radio station? Four hours of chamber music through the ages -- from the Renaissance to the present -- will be punctuated with discussions of where and when chamber music can be heard this season in Washington. The answer, you'll find, is everywhere from college campuses to concert halls.

Some may find that the better way is taking advantage of a different sort of radio opportunity -- next weekend's repeat performance of "The History of rock and Roll" (WASH-FM, 97.1 MHz) -- 52 hours of music and documentary reviewing the past 25 years of rock and roll. The music of artists from Chuck Berry to Fleetwood Mac (with, of course, Elvis in between) will be accompanied by interviews with some of the most significant musicians, writers and producers of rock and roll.

But you can also do both.

"Chamber Music: Live From Studio 2." Today, 1 to 5 p.m. WAMU-FM. "The History of Rock and Roll." Sept. 1, 5 p.m. to midnight; Sept. 2 through 4, 9 a.m. to midnight. WASH-FM. For schedule information call 244-9700.