Lady Lark was among the most tragic members of the Squadron Supreme. As revealed in the Squadron Supreme limited series, Linda Lewis had been a successful recording artist until an accident damaged her vocal cords. Following an operation, new vocal cords gave her superhuman sonic powers. As a drawback, however, she could no longer sing (Squadron Supreme #1, #4). In some respects, Lady Lark's music career had parallels to that of Dazzler, a singer whose mutant powers over light and sound propelled her into the role of reluctant superhero.
Like other early members of the Squadron Supreme, Lady Lark had a counterpart in the Justice League of Americaspecifically, Black Canary, with her ear-piercing "canary cry." On top of that, Lady Lark's on-again, off-again relationship with teammate Golden Archer was an homage to Black Canary's romantic pairing with Green Arrow in DC Comics.
This image of Lady Lark comes from Avengers #147 (May 1976). Since her powers often appeared as music notes, singing may have been how Lady Lark activated her superhuman abilities.