I had these very questions this morning while listening to Lorez Alexandria The Great on Impulse! Her pitch is flawless. A fair amount of Sarah, a dash of Carmen, a pinch of Dinah, and likely others in the mix that I can't hear. I wonder who got her on Impulse.
Just found this quote online regarding Alexandria's second and third recordings for King:
โIn 1959, she recorded two more albums for King, but the label, instead of hiring an arranger and musicians for the sessions, used pre-recorded instrumental backgrounds for Lorez to overdub her voice. She did a wonderful job interacting with them, in some of the finest work by this much forgotten jazz legend. It is no wonder that throughout her career, some eminent jazz critics compared her with Dinah Washington, Sarah Vaughan or Carmen McRae.โ