After playing together just five years, brother and sister duo Matthew and Eleanor Friedberger’s wacky rock outfit, the Fiery Furnaces, is already one of the most accomplished bands on the indie scene.

In that time, they have released three albums: 2003’s groundbreaking “Gallowsbird’s Bark,” the quirky sophomore follow-up “Blueberry Boat” (2004), and a collection of the Furnaces’ B-sides and UK singles entitled “EP” (2005).

They’ve built a reputation of creating originally spastic music and have toured with such high-profile bands as Franz Ferdinand, Spoon, and the Shins.

Their latest release, “Rehearsing My Choir” is a collaboration with the Friedbergers’ grandmother, Olga Sarantos, the ex-choir director of a Greek Orthodox Church near the band’s home in Oak Park, Ill.

From a social history standpoint, the album’s premise is intriguing: a series of duets with grandma concerning life in Chicago throughout the twentieth century. While Matthew toils away on acoustic guitar, organ and harpsichord, Sarantos and Eleanor lavish the audience with detailed accounts of the former’s days as a youth in the Windy City.

From a band like the Fiery Furnaces – one that has made its name by fashioning extravagant music – an album that focuses on narration itself does not make sense.

Seasoned fans will anxiously wait to pick up the album, but the Furnaces’ new album is a uniformly drawn-out effort and just doesn’t deliver.

Sarantos’ voice is wholly annoying; her singing (more aptly described as speaking) is monotonous and monosyllabic. Eleanor, supposedly taking on the persona of her grandmother’s younger self, sings unemphatically and adds to the ennui of the record.

Instrumentation is likewise sparse. Many songs consist solely of a subdued piano or organ to accompany Sarantos’ droning voice. Rarely is there guitar, and when there is, it’s usually a soft acoustic.

Only a few times do the Furnaces break out of their newfound penchant for slow-core and pay homage to their spaz-rock beginnings with a distortion-heavy guitar and wacky synth.

In “The Wayward Granddaughter,” the Furnaces do so by flaunting a disco dance beat, jaw harp, and harpsichord that create a catchy and innovative sound. But just as they finally pick up the tempo, they suddenly revert back to Sarantos’ dull monologues.

In comparison with earlier albums, “Rehearsing My Choir” is infinitely tame. Old Furnaces tunes like “Tropical-Iceland” and “Chris Michaels” were full of sound, employing varied instrumentation and spastic noodling. Unfortunately, there is nothing as elaborate on this album.

The Furnaces try their best to salvage some shred of musicality in “Rehearsing My Choir” by sloppily attempting to include Matthew’s instrumental fiddlings throughout the tracks. Most of time, though, the music merely reflects the sentiment of the narrative – a melancholy organ connotes nostalgia for the past in “We Wrote Letters Everyday,” and pensive piano recreates a solemn feel in the funereal “Does It Remind You of When.”

This just proves that the social history aspect of the album is more important than the music; the music embellishes the narrative instead of the other way around.

“Rehearsing My Choir” does not live up to the Furnaces’ inventive musicality on their earlier albums. Quite simply, it fails to demonstrate the creative genius made the band successful in the first place. Instead, the Fiery Furnaces de-emphasize their music to accent the histories of their grandmother’s life.

To totally rip this album wouldn’t do it justice. It’s a creative idea, but as a record it falls short. Compared to their earlier releases, “Rehearsing My Choir” is simply boring.