Helen Schneyer, a fine singer of traditional American songs, will perform a benefit concert for the Washington Waldorf School in the school's auditorium on the grounds of the Washington Cathedral today at 3. Schneyer specializes in ballads, work songs and religious songs. "The only kind of songs that I sing are songs that have some sort of significance for me," she says. "I have a lot of trouble singing about kings and queens unless what befalls them is exactly the same thing that would befall me or the janitor."

So how does a nice middle-class Jewish girl from the Bronx end up with a repertoire so deeply drawn from the Baptist well? "The first music that I remember as a babe in arms was from a black Baptist church in New York," she says. "So it's no accident that I sing so much Baptist stuff. As far as I am concerned they sing better than anybody because they haven't been shriveled up with good mannners in their expressions of their love of God, or fear or hate, or whatever it is. The higher you get in the church, the more stale it gets until you get to the point where it becomes a nonparticipating sport and you have a splendid choir that does the singing."

Schneyer's immense reservoir of songs stretches from revolutionary times through the Victorian era and into the traditional music of the '30s and '40s. She performed for the Roosevelts at the White House and in a John Cage composition with five major symphony orchestras. She has also just released a new album of spiritual songs, "On the Hallelujah Line" (Folk Legacy-SSI-85).

One thing you can count on: Schneyer will be singing loudly. "This is something that almost everybody has done at one time or another, and it is no job at all to get an audience to sing gospel or spirituals with you. They'll join you on that, and that is my favorite sound.