Past outings from Brooklyn duo Ratatat have been marked by bright lines, big blocks of color, and a sort of inoffensive coolness. It was electronic music delivered by cock-rocking guitarists, but with most of the gristly bits polished away: Think arena-electro for grocery-store aisles. But LP4 is refreshingly strange, the kind of album that’s fine to zonk out to, but even finer to pick through with a big set of earphones. Take the opener, “Bilar”: After a few seconds of rising noise, the beat kicks in, and it’s the heavy, clattering sort of arrangement you’re likely to hear plenty more often now that Flying Lotus has arrived. Somewhere in the mix, a cash machine spits out quarters. Elsewhere, the addictively busy swampland boogie of “Neckbrace” recalls Yello’s cheese classic “Oh Yeah” and contains a brainteaser: Is that earworm being created by a bass guitar, a keyboard, or someone’s voice? Of course, adding new ingredients isn’t itself a recipe, so Ratatat’s base-level charms are the same as ever: sunset-pretty breakdowns, birdsong guitars, stiff beats, joy gilding melancholy. Many of the tracks merely fade out rather than hitting a discernable climax, but it’s to Ratatat’s credit that it’s so entertaining to hear them dig around in the studio sandbox.