''You belong to a simpler time/I'm a victim to the impact of these words/And this rhyme,'' sings Shins frontman/songwriter James Mercer on Wincing the Night Away, sounding distinctly burdened and world-weary. It's one of the least attractive postures in pop woe is me, the fans are hanging on my every word but if anyone is entitled to it, it's Mercer and his bandmates. Over the past five years, the Shins have found themselves transformed from a little cult band to million-selling indie-rock icons. The inclusion of their gorgeous folk-pop ballad ''New Slang'' on the 2004 soundtrack to Garden State the song that Natalie Portman's Sam declared would ''change your life'' further elevated the band to the role of bards of Generation-Y angst. It's hard to imagine less likely spokesmen than the Shins, whose smart, pretty music is so determinedly low-key and introverted. Even their most buoyant songs sound like diary entries music for private contemplation, not group uplift. Mercer and company have responded to the heightened expectations surrounding their third album in a predictable way: by enlarging and eclecticizing their sound. Thus the album-opening ''Sleeping Lessons,'' which begins with Mercer singing over a spiraling synth figure and builds into the loudest, grandest guitar rock the band has recorded to date. Elsewhere, the Shins dabble with hip-hop beats, swirling string arrangements, and fuzztones reminiscent of early Jesus and Mary Chain. Some of these departures fall flat. (''Sea Legs'' is a meandering exercise in psychedelia with a surprisingly shapeless melody.) Like a lot of bands fiddling with synthesizers for the first time, the Shins are occasionally too enamored of texture at the expense of tunes.
The best moments are the more traditionally Shinsian. When he's on, Mercer is a great songwriter, crafting classic pop-rock melodies that leap across octaves and twist in unexpected directions. Case in point is the terrific single ''Phantom Limb,'' propelled by a monster buzzing bass line and Mercer's Morrissey-esque crooning, which strikes the ideal balance between old-fashioned guitar pop and the Shins' new sonic experimentation.
Mercer's words, meanwhile, are odd and engrossing: He's one of indie rock's finest lyricists, even especially when he's not making much sense. ''Every post you can hitch your faith on/Is a pie in the sky/Chock full of lies/A tool we devise/To make sinking stones fly,'' he sings in ''A Comet Appears.'' Not just any person can take a massively mixed metaphor like that and make it sound like a clue to the riddle of existence. It takes someone special you might say it takes a rock star. B+