“When it comes to interviews , it’s whatever people ask, and I try my best not to answer it,” said Ira Kaplan, Yo La Tengo‘s jocular guitarist and singer, at the end of our phone chat yesterday, dodging the most customary of questions: “Do you have anything else to add?”

It wasn’t his first demurral. I floated a few theories about the deceptively simple title of the Hoboken, N.J., trio‘s excellent new album, Popular Songs—how the band has long been indie rock’s best synthesizer of cool aesthetic and good (read: rock-nerd) taste, and how now, more than ever, the group seems to be playing with ideas of nostalgia and shifting media. “Well I think that … ,” Kaplan said, trailing off. Strike one. “I’m not really going to tell you. We had the title for a while, and when we approached [cover artist] Dario Robleto about using his work, the way he used physical materials in his work seemed to really resonate with the title.”

Our conversation turned to the group’s current tour (Kaplan and his bandmates, drummer and singer Georgia Hubley and bassist James McNew, perform tomorrow night at the 9:30 Club) and then back to the new album—specifically, its dramatic string arrangements by the Chicago bass player Richard Evans. I told Kaplan that the ominous, swooping arrangement on “Here To Fall”—the album’s opener—reminded me of a Serge Gainsbourg song. Strike two. “I suspect Richard wasn’t thinking of Serge Gainsbourg. Richard made some incredible records in the ’50s and ’60s, so maybe it’s that Serge Gainsbourg heard what [Evans] was doing. Or maybe great minds just think alike.”

Things picked up as we discussed “If It’s True,” a concise love song whose effervescent bass line and amorous orchestrations wouldn’t feel out of place on a vintage Impressions record: “That was a song that structurally didn’t change that much. When we were rehearsing it I was primarily playing piano”—not Kaplan’s strongest instrument, he conceded—”so James carried some of the more melodic weight. He started playing this much more complicated bass line and the song was getting much more into the Motown bag, and it had kind of started there to begin with. At an earlier point in the band’s life, if we had a song that was really Motown, we’d come up with an element that would make it less so, but lately, we try to come up with an element that will make it more so.”

He said that sometimes a song will emerge fully formed, Athena-style, from the band’s head—like “Avalon Or Someone Very Similar,” the bounciest slice of AM pop on Popular Songs. Most of the time, though, “our writing tends to be pretty loose,” Kaplan said. “Almost every song has some sort of genesis as one of these long sprawling things.”

Given that methodology—in which songs are molded more than written—Yo La Tengo’s prolificness can be surprising: In 2009 alone, the group has released a proper album, a film score (Adventureland), and a disc of covers under a pseudonym (Condo Fucks’ Fuckbook). “In some ways it becomes a decision to not do [nonalbum projects],” Kaplan said, “because somebody asks you do something and it seems like such a cool opportunity. And at a certain point we realized we hadn’t done a record in a long time. ‘Maybe we should say no.’

“Basically we went to Matador [Records, the band’s longtime label] and said, ‘If we were to put out a record, what day would be good for you? What day would you shoot for?’ And they looked at their record schedule and said Sept. 8. And we used that as a finish line.”

Kaplan said Yo La Tengo will tour through the rest of 2009—a year that, not coincidentally, marks the band’s 25th anniversary. And so I posed the obvious question. “Is it weird? It is a little weird,” Kaplan said. “It’s like being on a long line, and you feel the line’s not moving, and then you look behind you and see how many people have got on the line, and you say, ‘I guess I am moving.'”

Yo La Tengo plays with Endless Boogie tomorrow night at the 9:30 Club. Tickets are $20, and doors open at 7 p.m. Photo courtesy of Yo La Tengo’s MySpace page.