THE FIFTH New Music America Festival, a week-long showcase for new directions and experiments in music, is scheduled to take place in Washington Oct. 9-15. It will present the performances and works of close to 100 vanguard artists in concerts, exhibits, seminars and workshops.

While the list of participants has not been made final, among those expected are Philip Glass, Jon Hassell, the World Saxophone Quartet, the New York Hot Trumpet Rep. Co., Diamanda Galas, Leroy Jenkins' Sting, Rhys Chatham, Jamaladeen Tacuma, David Van Tieghem and Carla Bley. The program will mix established and unknown artists; local groups include the Aerophone Society, the Contemporary Music Forum, Scriptronics and the 20th Century Consort.

A budget of $200,000 has been adopted, and the mayor's office has already committed $50,000 and one night's free use of the new Convention Center for a concert. Other funding includes $25,000 from the National Endowment for the Arts' Interarts Program for sound installations, $7,700 from the NEA's New Music Division and $15,000 from the Martha Baird Rockefeller Fund for Music. Deborah Hanzlik of the Washington Performing Arts Society said only a small portion of the budget was expected to come from ticket sales; "We don't want to make this out of anybody's range."

New Music America will precede the third Ninth Street Festival and, like that event, continues the partnership between WPAS, for 16 years one of the major arts promoters and producers in America, with District Curators Inc., a five-year-old group fostering new directions in dance, music, performance and media arts.

The New Music America festival kicked off in 1979 in New York City with 50 performances.