Less than a minute into the second track, “Down Boy,” on the Yeah Yeah Yeahs’ latest EP “Is Is,” lead singer Karen O takes a deep breath. The song has opened tentatively with a cloud of ethereal, trilling guitar lines and a gentle ringing on Brian Chase’s highhat. Karen chimes in, meditating opaquely on fame and sex, as is her wont. Nick Zinner’s delicious guitar lick charges forward, and Mr. Chase chases them down with a violent, frighteningly efficient barrage. The spasm swells and cools, to resurface again less than a minute later.

For a band as culturally interpreted as the Yeah Yeah Yeahs, it’s difficult not to read every move as a meta-narrative. “Is Is,” out today, collects five tracks from the band’s live roster. They’re older songs, of a raunchier, more voluminous variety than we’ve heard from the band in what is now, astonishingly, half a decade. Might we herald this a return? A concession? It’s more of a reconciliation.

In 2001, the Yeah Yeah Yeahs were the band that was more New York than New York itself. After two rough, breathless, and earthshaking EPs, the goth, the drunk, and the misfit were anointed hipster heroes. Six years later, the press release accompanying “Is Is” plays up Karen O’s vivid idiosyncrasy by calling her a “drunk,” but that won’t do anymore — it’s too culturally acceptable. The early Yeah Yeah Yeahs was a band of contradictions, a constant conflict of pop veneer and primal rage. See, for reference, “Art Star,” from the group’s self-titled 2001 EP. This is not the nostalgic condescension of a self-appointed insider: The Yeah Yeah Yeahs were never a punk band proper, and in sacrificing volatility, they’ve also safeguarded against inconsistency. If Mr. Zinner’s guitar trills seem contrived, it’s because so many have since channeled the stringy, pompadoured finger wizard since he made it fashionable. And if the military-style precision of Mr. Chase’s drumming still sounds fresh, that’s because it’s impossible to imitate.

“Is Is” finds a band more comfortable with its fateful careerpath. The songs here are generally more aggressive than on 2003’s “Show Your Bones.” They boom, although they’re hardly rough. This is a self-conscious move. “10 x 10” dabbles coyly in the band’s gentler inclinations; Karen O touches her toe to the line with a quiet chant, before Mr. Zinner’s guitar drags her in: “Out of my mind / Stolen my wife / Stolen my night / Gonna take him into my life.”

The Yeah Yeah Yeahs have modulated their sound so as to accommodate pop music, and in so doing they’ve moved the boundaries of that genre. They make music that’s not always pop, but which has accrued large market popularity. Tegan and Sara, who today release their fifth album “The Con,” do just the opposite: They make radio-ready music that hardly makes it to radio.

Tegan and Sara were discovered in 1998 at a Calgary guitar festival, or so the story goes. The Quin sisters (they’re identical) do everything together — they sport fashion mullets and write and sing music. You might differentiate them by the tone of their voices: Sara’s is the higher. After garnering the highest score ever at that festival, they were picked up by Neil Young’s Vapor Records, and during the last decade they’ve have built a healthy, though primarily indie, fan base. “The Con” is the duo’s fifth release, and their first on Sire Records.

Tegan and Sara have been making music together since they were 8-years-old, but their pop songs are wildly inorganic, constructed as if by sheer force of will. Take, for instance, the production, which is dense and candied throughout. On tracks such as “Back in Your Head,” the thick, Avril Lavigne-intensity production works wonders; ditto for the skate-pop stylings of “Hop a Plane,” which counts more hooks than lyrics. On most of the tracks, Tegan and Sara throw so many melodies out one after another, like so much spaghetti on the wall, that many come out undercooked. But really, who is going to clean up all that pasta?

All too often quantity comes at the expense of cleverness, subtlety, and artistry. Witness the leaden lyrics in the refrain to the title track: “Nobody likes to but I really like to cry / Nobody likes me / Maybe if I cry / Nobody / Encircle me, I need to be, taken down.” Another track, “Are You Ten Years Ago,” advertises itself as a romantic thriller, its refrain delivered shrilly and urgently, its lyrics action-packed. The song is a straightforward proclamation of romantic loss and loneliness, presented in an abundance of exaggerated feelings. Lyrics like “When you get so into yourself / I lose sight of common goals / And letting go so I can be all alone” pack all the emotive punch of CliffsNotes.

Pop music has always been about giving some and holding back some. Too much and you’ve got Prog Rock, or Tipper Gore breathing down your neck. That’s why Karen O purrs once she’s growled, and why the Yeah Yeah Yeahs have made mainstream radio their glamorous bar stools. For identical twins especially — attractive identical twins, singing of love in tight jeans and tighter harmonies — a certain delicacy is in order.