The first two tracks of Centaur Noir's Rock the Hall are a study in contrasts. Lead track "Market Street" is a dusty piece of lonesome folk -- guitar, percussion, and a little harmonica under restrained twin vocals, one falsetto and one a hoarse croak.

It's followed by "Only English Spoken," with blunt beats and dominating electronics overwhelming the vocals.

So Centaur Noir, a solo project of Meth & Goats frontman (and Moline resident) Jon Burns, embraces a dual nature. Sometimes the two sides meet -- as on album standout "Ten More Years," in which the lead acoustic guitar is balanced by soft, droning synthesized melodies. But even when they do converge, each song's heartbeat is clearly either folksy or electronic.

The band Fang Island -- playing the former ComedySportz location in Rock Island on Monday -- is named after a place from a story in The Onion, but it would be a mistake to infer that the band is in any way a joke. There's certainly a silliness there -- guitarist Jason Bartell admitted that many songs start with "cheesy" riffs -- but it's also nakedly sincere.

Think the unapologetically adolescent approach of Weezer, or the id arena rock of Andrew W.K. as starting points. But Fang Island benefits from having few lyrics -- and because they're generally shouted by a group, they barely register. Fusing big, bright, loud guitars, strong melodies, and some prog-rock unpredictability and complexity, the band makes a joyful noise unfettered by angst. As Pitchfork noted: "What helps Fang Island steamroll past cynicism is how 'fun' isn't just an ornament for them; it's embedded in the band's musical DNA."

"I think the best way to make music is that middle line [between] ... not taking it seriously enough and taking it way too seriously ... ," Bartell said in a phone interview this week. "It comes down to honesty in some ways." The band needs to pursue its aims "in a very pure way," he added.

Chevelle's Sci-Fi Crimes raises one major question: Does the band believe in the paranormal subject matter it tackles with such earnestness on its 2009 record?

"Pete and Dean and I have this ongoing discussion about whether it can happen, whether aliens can even reach us," said drummer Sam Loeffler in a phone interview last week. "It's all in fun."

Which is to say that the members of Chevelle -- brothers Sam and Pete (guitars and vocals) Loeffler and brother-in-law Dean Bernardini (bass) -- aren't believers. Yet.

So when Chevelle headlines Saturday's Rock the District event in Rock Island, feel free to share your beliefs, theories, and evidence with the band. Sam, at least, claims to have an open mind.

Dan Snaith sounds tired of answering questions about math.

He comes from a family of mathematicians; he earned a Ph.D. in the field in 2005. And because he records and performs (under the name Caribou) electronic music, journalists (this one included) ask him a lot of questions about the relationship between his primary academic and musical pursuits. They both involve computers, don't they?

Snaith -- who will be playing with his band at a Daytrotter show at RIBCO on Saturday, June 5 -- said there are some similarities. But not many. "Being able to do what you want ... is kind of an intuitive process," he said in a phone interview last week. "In both mathematics and in music, you kind of have to use some gut-level intuition to piece things together. [But] I think they're very different in many ways."

What's evident listening to the music of Caribou is that Snaith's electronic instruments are largely tools, not ends. There are certainly electronic sounds, but the songs sound organic and feel handmade, and his singing voice is ethereal, warm, and emotive -- a perfect offset to any digital coolness. Put differently, there's nothing mathematical about Caribou's songs.