MIDWAY THROUGH "Close Chorus," a track on A Sunny Day in Glasgow's 2009 album Ashes Grammar, there's a break on which a brass sample rises from the reverb-flooded song. Listen closely and behind it you'll hear lightning crashing against the tin roof above the recording space, a semi-abandoned dance studio in New Jersey. It's an illuminating window into both the physical environment and larger sound that have been visited by the Philadelphia outfit since their 2007 full-length debut, Scribble Mural Comic Journal.

Back then, Glasgow was bedroom pop riddled with noise, tamed by the coo of co-vocalists Lauren and Robin Daniels, the twin sisters of brother and band co-founder Ben Daniels (Ever Nalens, who named the band, left before their debut). Many pundits called it shoegaze, a label Ben steers clear of. "I don't care for any descriptors really," he says. "They usually do more harm than good."

When Journal appeared, critics fell all over themselves finding ways to cite Glasgow's cobbled lineage. Drowned in Sound raved that it "deconstructs the best parts of tried-and-tested genres and pastes them into one sonically astounding collage." Pitchfork laboriously quoted a review of The Velvet Underground and Nico from an obscure rock rag. This kind of talk is the indie rock press' mealy-mouthed equivalent of a knighting.

In 2008, Lauren and Robin left for non-musical pursuits and Ben began using the dance studio on weekends. "We had a huge room, so it made sense to put mics all over and see how things sounded," he explains. Much of this experimentation was influenced by composer Alvin Lucier, whose signature work, I am sitting in a room (1969), gradually layers natural reverb in such a way that it completely washes out the original source. Applied to Ben's melodic reveries, the result is Ashes Grammar, an album boasting an acoustic depth practically unheard of in the Pro Tools era.

Now with two new vocalists (Annie Fredrickson and Jen Goma) replacing the Daniels twins, the project is on its sturdiest footing to date. A Sunny Day in Glasgow may not be a shoegaze band, but, at long last, they are a band.