In person, the Yeah Yeah Yeahs’ ferocious sound doesn’t differ enough from that of their three fine full-lengths and innumerable EPs to make a live album a necessity. But if they decided to cash in with one, I’d buy it just for frontwoman Karen O’s stage banter, which, through sparse, has the advantage of sounding like it’s being translated from Japanese.

At a sold-way-out 9:30 Club Friday night, she introduced the New York art-punk trio’s (reinforced by a part-time fourth member) biggest hit, the ballad “Maps,” thusly: “Time for the Yeah Yeah Yeahs love song, all right!” And right there you’ve got about half the 15 or so words she spat during the 15-song, 70-minute mission, aptly summed up by the title of their current release, It’s Blitz! The album is awash in icier, synth-ier textures than its comparatively raw predecessors, but onstage the group — nurtured in its early 21st-century infancy by boosters like The White Stripes and P.J. Harvey — remains as feral as it is theatrical.