★½ out of four stars

Rated: R.

Theater: Edina.

“Mommy” sheds harsh light on the day-to-day torment of caring for and containing a teen son with severe behavioral problems. At times, it’s hard on the eyes, but it’s really hell on the ears.

A Quebeçois widowed mother in her mid-40s, Diane “Die” Després (Anne Dorval) retrieves her extremely wayward only child, Steve (Antoine-Olivier Pilon), from a youth detention center after he gets kicked out for setting another boy on fire.

Scrabbling for work while dressed like a rocker/biker chick half her age, hard-living Die tries to set up a new future for the two of them in an apartment more down-at-heel than other homes on their suburban street. Their intense love for each other — Steve’s displays of affection venture into inappropriate territory now and then — is soon strained by near-constant, curse-laden French-Canadian screaming matches visually underscored by subtitles.

Things start looking up, but not for long, after they befriend neighbor Kyla (Suzanne Clément), a former teacher who, following some mysterious trauma, has become so introverted she can barely speak and shows more interest in her new pals than her own family.

Only 25 years old, Canadian filmmaker Xavier Dolan is on his fifth feature as a director. A Cannes darling who also designed the film’s white-trash costumes, he shows an impressively mature knack for slipping inside the minds of female characters twice his age. But he goes overboard on the abrasive screechfests between mother and son, making you wish for noise-cancelling headphones.

The sustained cacophony quickly goes from shocking to tiresome, marring the story’s more touching and humorous moments.

Dorval has appeared in three of Dolan’s previous features, Clément in two and Pilon one, and it shows. A tight rapport between director and actors translates into effortlessly intimate scenes as Die, Steve and Kyla, who begins home schooling the boy, grow closer.

But Steve’s diagnoses — including ADHD and a possible attachment disorder, which have grown worse since his father’s death three years earlier — only scratch the surface of the dangerous volatility simmering beneath.

With the exception of one dreamlike sequence near the end, Dolan shot the film in an unusual 1:1 aspect ratio — a perfect square — because it frames the characters like album covers, cutting down on peripheral distractions to draw focus to faces. It’s a bit unsettling at first, but becomes part of the movie’s singular stamp.

In the beginning, as Die is on her way to pick up Steve, another driver broadsides her car, leaving her dazed and bloody, yet he and several bystanders do nothing but stare at her fretfully. Later when a major character lies bloodied in a supermarket aisle, onlookers demonstrate a similar passivity. These scenes underscore an “us against the world” outlook for the odd trio.

“Loving people doesn’t save them,” says a youth counselor suggesting that Die consider committing her son to a mental institution. “Love isn’t enough.”

Knowing that, yet never wanting to stop trying, is the tragic futility at the center of “Mommy.”

Heartbreaking, if you can get past all the yelling.