POP MUSIC : **** SONIC YOUTH, “Dirty”. <i> DGC</i>

Sometimes it seems as if Sonic Youth is working in a medium that only peripherally resembles rock ‘n’ roll, some kind of rarefied meta-medium that floats above, around and through stuff like Led Zeppelin and Madonna. Sonic Youth rocks, sure--listening to “Dirty,” you can’t help wanting to dive headfirst off a stage--but its music works on so many more levels that a few spins can make your brain start to hurt.

Some weird ‘60s stuff is going on here, fuzzed-out and syrupy-melodic, some of it derived from obvious sources like Blue Cheer and Donovan, most of it grabbed in soft fistfuls from the infarcted heart of high-calorie psychedelia . . . but even if Sonic Youth covered “Sunshine Superman” note-for-note, which it assuredly doesn’t, it would come out sounding 100% Sonic Youth.

This time, the New York noise band eschews the meta-metal of 1990’s “Goo” for something like the more pop-based approach of its 1987 album “Sister,” only more refined: tough, politically cool songs, blanketed with swaths of oddly tuned guitar, overtones and squeals and dissonances ringing into the ether. Producer Butch Vig seems to have roped in the most obvious Sonic excesses, but as with any Sonic Youth album, some of the best parts are the ones only dogs can hear.

Albums are rated on a scale of one star (poor) to four (excellent).