Tune-Yards, Shepherd's Bush Empire, London Is it a tribal chant or a yodel? A squawk or a chirrup? Merrill Garbus - aka Tune-Yards - is back, after the triumphant critical success of last year's album whokill, and live she's as arresting as ever. There's the trademark streak of warpaint and a warm grin across her face; she stands in just her socks. In an unaccompanied intro, she uses that incredibly powerful voice as a teasing instrument, and looping pedals to layer up the different vocal effects, before starting to whack two upright drums. "Do you wanna live?" she bellows, before launching into a call and response of "yeah!"s. Life affirming? You bet. Tune-Yards' sound has certainly beefed up since Garbus' bedroom recording days, and it's a shame that nothing from her 2009 DIY début Bird Brains get a look in tonight. But the follow-up has clearly won her a legion of fans; it's rare to see this level of enraptured engagement at a gig. It's obvious why, though. The trick they pull off, ('they' being Garbus, bassist Nate Brenner, plus two saxophonists) is being technically tight and impressively complex while still playing rollicking good-time music. Most tracks are gradually built up, with Garbus banging out interlaced, complicated rhythms, recording as she goes and stacking them on top of one another, before repeating that process with her vocals, and finally there's an injection of funk with a driving bass line or a wild sax refrain. One minute you're marvelling at how she can multitask with a smile, hands tapping while feet fiddle with pedals; the next you're not really thinking about the technicalities at all, but are just swept along. There are sublime moments in most numbers: when the growling bassline on 'Gangsta' is supplemented by siren calls from Garbus' voluminous lungs. Or when she shifts from a wryly knowing rap to singing into her ukulele as a vocal echo chamber on 'Killa'. Or when the bass kicks in on 'Powa', and it shifts from a loopingly harmonised lullaby to a low-slung, pelvis-rocking groove-fest that has the audience head bouncing as if they were at a hip-hop gig. This is their largest headline show yet, and certainly feels less cosy than previous Tune-Yards gigs. But while the intimacy, and between-song chatter, may be lost, the bounding, beaming, heart-swelling boldness of it all still remains. Do you wanna live? You don't have much choice but to accept the challenge.