At 20, Tash Sultana shows a mastery of atmosphere that might make artists three times her age writhe in envy. On the Australian singer/songwriter’s impressive debut EP, rhythmic guitars ring with Clapton-caliber swagger as fingersnap percussion sends ripples through shimmering, limpid synth pools. Her supple voice shifts to accommodate her songs' changing weather. Against the cloudy chords of “Synergy,” she purrs and then flashes a lightning-like hiccup; on the loping, reggae-infused jam “Jungle,” her soulful, layered vocals adopt a breezy drawl.