Giant sound: Some bands just have the knack.

A set of headphones will likely cancel out any distractions or outside stimuli, this enveloping and overwhelming colossus morphing from the amplifiers of doom-laden, post-metal trio Ufomammut being of considerable weight. The band’s first chapter in their new project, Oro, Opus Primum is a solid 51+ minutes of towering height, large structural masses of sound too significant to negotiate.

Written as more of a “movement” or “suite,” Opus Primum is thematically structured around its near-14 minute introduction, “Empireum,” the track’s guiding and spare notes anchoring its trudging build. The piece easily qualifies as overlong, but the subsequent payoff of the following track, “Aureum,” discounts any indication of pretension or self-indulgence. Spacey and heavy, fattened chords thick enough to crush a small kitten, a stunning clarity despite its Sabbath-inspired sonic tar, it’s difficult to be anything other than fully invested in Ufomammut’s opus by “Aureum”’s closing, the following track, “Infearnatural,” grinding and repetitious, choral vocals softening its bristling edges.

“Magickon” revisits “Empireum,” a selection of electronic sounds and indecipherably altered vocals flanking the basic idea. Guitar sounds emerge, cymbals crash, the drums begin and the strings are leaned upon, the riffs ground into assaultive energy. The size of the album becomes staggering and it takes on more of a meditative tone by “Mindomine,” whose drones and phrasing strike similarities next to the type of bass/drum/chants that Al Cisneros’ post-Sleep act Om employs. As if endlessly searching for its own soul, Opus Primum digs deep into enormity, the album’s limitlessness of sound both an enticing draw into Ufomammut’s vision and as an enthralling primer for their follow-up, Opus Alter.