Trying to find the title of a hauntingly beautiful song from 70s or early 80s. Only saw part of the video once quite a while ago. Made in the States I'd guess. I remember quite a bit of blue in the backdrop. Possibly blue dress. Background beat was a steady electronic "DADA da" throughout. Didn't hear any lyrics but there was a black lady alone on stage simply singing:
"Laaaaaaaa lalala lalala lalala lalalaaaa"
She'd start on a fairly high note then each following segment was slightly lower than the previous one until at the very end of the line there'd be just a sort of levelling off in tone on the last couple of "a"s. Then she'd repeat the line starting over on a slightly higher or lower note.