They look a little dirty, and after spending the summer on the road, they probably smell a little dirty, too. But they definitely don't sound dirty. The Brooklyn four-man band Dirty on Purpose has a self-described "emotional space-rock" style. All four members are songwriters who seem to be trying to cram as much music as possible into a single song. Complex harmonies, gloomy vocals, and steady rhythms are standard issue for the tracks on their debut full-length album Hallelujah Sirens, which was released in June on indie rock label North Street Records. But the songs are also peppered with horns, strings and various noise washes that give it a kind of hazy, zone-out effect that you can easily settle into. It's good road trip music . . . it's good trip music, if you're not afraid to experience a Sonic Youth circa 1980-something flashback.