Aaliyah left an indelible mark on contemporary R&B and pop before her still-promising career was tragically cut short at age 22 by a fatal plane crash. Assured from the start with her smooth, elastic soprano and casual demeanor, the singer introduced herself with a Top Ten hit, "Back & Forth," which helped drive its parent album, Age Ain't Nothing But a Number (1994), to multi-platinum status. Through her similarly successful follow-up, One in a Million (1996), she played a major role in popularizing the stuttering, futuristic production style that consumed commercial music in...