The first thing people notice about any record is its title. "Summer Sun," the latest offering by Yo La Tengo, might appear to be a collection of bright pop singles. Indeed, the band has covered the Beach Boys in the past and always includes original pop songs on their records amid the ambient experimentation and feedback-fueled freakouts. But the second thing people notice about a record is its cover art, and here we see the band's three members dressed for winter under an overcast sky.

Leader Ira Kaplan has never been one to encourage, much less live up to, stylistic expectations, and the album's opener, "Beach Party Tonight," inflates the cognitive dissonance between the implications of the title and the reality of the music: smoky layers of keyboards and incomprehensible vocals gently floating into the distance. Die-hard fans may be disappointed with the almost total absence of full-on rock, but they shouldn't be surprised. Most of the songs on "Summer Sun" incorporate the jazz that made guest appearances on YLT's most recent efforts, namely an instrumental soundtrack for silent French science films and an EP containing four versions of Sun Ra's "Nuclear War."

By increasing the participation of vibes and flutes and reducing the fuzzbox guitar, YLT doesn't so much calm down its music as give it more clarity and bite. In the blissfully discordant "Don't Have to Be So Sad," with its eerie keyboard fills and Kaplan's nasal vocals, the band reinvents itself as a brainy lounge act that doesn't require irony to be taken seriously, though seriousness isn't necessarily their intention. As an irresistible left-hand piano pattern and sci-fi effects buoy the weirdly funky "Moonrock Mambo," Kaplan runs through a thicket of obscure pop-culture references (" . . . like Timothy Carey in 'The Kill' . . . "); and the album's one true mambo, "Winter A-Go-Go," uses treated vocals to deliver a melody that might well have escaped from the last Chris Rea album. It's too warm for a song with "winter" in its title, but by this point you'll have realized that you shouldn't expect anything except that each new song will sweep you away.