Pop maven Sia chooses not to show her face very much, but she proudly wears her musical lineage on her sleeve. When she lets it all out vocally, there’s an echo of Björk’s uninhibited howl and fearless experimentation. And when she jumps genres, we hear Madonna’s willingness to shapeshift while never missing a beat on the dance floor, while Stevie Wonder’s elastic funk and Malcolm McLaren’s playful hip-hop fuel her quest for perfect pop.