CAPTION: Picture, Ysaye Barnwell, Evelyn Harris, Yasmeen Williams, Bernice Reagon. The call-and-response tradition of black music is alive and well in the voices of Washington's own "Sweet Honey in the Rock." Despite the avalanche of electronic music and formula disco, Sweet Honey is celebrating its seventh anniversary this year. The quartet of four black women sing a cappella music assisted only by gourd shakers, foot tapping and hand clapping. Founded by Bernice Reagon at a workshop at the D.C. Black Repertory Theater Company, the group has had 15 other members in addition to Reagon. The quartet now consists of Reagon, Yasmeen Bheti Williams, Ysaye Barnwell and Evelyn Harris. As fast as music groups come and go, that the group has survived is a major accomplishment in itself. According to Reagon,". . . this is a group of women that can withstand individually whatever we have to go through for the group. D.C. is a community that takes their music very seriously." Reagon says Washington is the first city where she's been in which she could be a singer, scholar, researcher and teacher all at the same time. Williams is the group's only native Washingtonian. Harris and Barnwell originally came to D.C. to attend Howard University. When they tell people whom they sing to across the country that Washington is their city, they stress that the people who are elected to Congress run D.C.'s city business, as well as the federal government. Reagon says voters "ought to be sure not to send people here who don't like black folk, 'cause then they just give us hell for the whole time that they're here." Because of family and job commitments, the group travels on weekends only. Being in the group helps them structure their personal lives. Harris says, "It either gets it totally together or it helps it to totally fall apart. It's a sacrifice to be in this group, but it would be a greater sacrifice not to be in Sweet Honey in the Rock." Members of Sweet Honey in the Rock feel that it is a transitional group heralding a new age of humanism and that if the world continues, it must deal with the needs of human beings balanced with human society and nature. For them the final reaction is from the audience. The lights are kept on during the concerts so they can see people's eyes. Sometimes they cry; sometimes they smile; sometimes they sing and shake their heads. There's a call and response between the group and its audience. After seven years of existence, Sweet Honey is celebrating its anniversary this Friday and Saturday with a harvest songfest. The group will record its third album, which will be its first live album. The concerts will be held at All Souls Church, 16th and Harvard streets NW, at 8 p.m. Tickets are $7. Signing for the hearing impaired will be available Saturday and child care will be available both nights. For information, call Roadwork and Friends at 234-9308.