The most gut-wrenching challenge of Maile Flanagan’s long acting career was playing a boisterous teen ninja coming face to face with his long-lost mother, just a week after the actress had lost her mom in real life.

“It was the hardest thing to do and one of the best things I’ve ever done,” said Flanagan, a former Minneapolis-based comic whose credits include “Grey’s Anatomy” and “The Station Agent.”

The performance wasn’t captured on a movie set or stage. It happened in a sound booth while Flanagan, 53, was overdubbing English dialogue for Naruto Uzumaki, the Japanese animé character who’s starred in six films, 700 TV episodes and 42 video games.

Voice-over artists such as Flanagan are being heard like never before, leading to more work and more respect. Anyone who thinks voice acting is child’s play deserves a swift kick in the head from Flanagan’s most famous character.

“For ‘Naruto,’ I may have to kill somebody, grieve over it and then be funny in the next scene. That’s never going to happen in a half-hour sitcom,” she said. “I’m a middle-aged actress. I’m never going to be Nicole Kidman. But in a cartoon, I can play sexy. It’d be a sexy woman with a raspy voice, but I could do it.”

In the past, Flanagan split her time evenly between animation and live-action roles. This year, she expects to spend 75 percent of her schedule doing voice-over work. Demand has risen sharply, thanks largely to the rapidly expanding population of Toontown, as new animated shows pop up on streaming services.

Netflix, which offers the critically acclaimed series “BoJack Horseman” and “Trollhunters,” hopes to debut 30 Japanese animé series this year. “Harvey Street Kids,” based on the gung-ho girls of Harvey Comics, debuts June 29.

Hulu’s most streamed program of 2017 was Comedy Central’s long-running “South Park,” which helps explain why the company just inked a deal with DreamWorks Animation, with new series debuting in 2020.

“There’s more animation work now than ever,” Chris Prynoski, president and owner of L.A.-based animation company Titmouse, told Variety magazine last year. Half of the company’s assignments are for streaming shows, including Amazon’s Emmy-winning “Niko and the Sword of Light” and Netflix’s “Big Mouth.”

Whistle while you work

Actors who think they can take advantage of this deluge of work by rolling into the studio in their pajamas and getting home in time for “Judge Judy” are in for a rude awakening.

“You start to get these jobs and you feel cocky, like, ‘I am great at this,’ ” said “Saturday Night Live” veteran Bobby Moynihan, who broke into the animation business by contributing to Pixar’s 2013 film “Monsters University” and now has a leading role in “DuckTales,” Disney XD’s reboot of the 1980s cartoon.

“Then you look at someone like John DiMaggio [Bender on ‘Futurama’] or Mark Hamill [‘Batman: The Animated Series’] — I could talk about his Joker for hours — and you realize, ‘I’m nowhere as good as these people.’

“On camera, I can make a tiny little eye movement and convey what I’m feeling. You can’t do that in animation. It has to come through solely with your voice. It’s an amazing skill.”

Alyson Stoner, better known as Isabella in Disney Channel’s “Phineas and Ferb,” sometimes does more research for her voice-over duties than for live-action roles.

When she was reinterpreting a part from a Japanese video game, she poured hours into studying the subtle differences between that language and English, trying to maintain the integrity of Japanese culture while striving to please representatives from both countries who were judging her throughout a 12-hour session.

“On camera, the crew is far away from you. But in voice-over, the executive is staring right at you from the other side of the glass, giving you feedback at a rapid-fire pace. And if you don’t do it correctly the first time, you’re replaced,” said Stoner, who also starred in the “Step Up” and “Camp Rock” movies. “I honestly don’t think everyone can do it.”

Hank Azaria has made it look easy for 30 years as the voice of Moe the Bartender and other characters on “The Simpsons.” But the actor, who appears in the flesh as IFC’s “Brockmire,” said that’s far from the truth.

“It might surprise you how much energy it actually takes to do a vocal performance,” he said. “You have to sort of act with your whole body or else it doesn’t come out good. ‘You do the Hokey Pokey and you turn yourself about.’ That’s really what it’s all about.”

You also have to be willing to make a fool of yourself.

“You can’t be afraid to look silly and try things,” said “Better Things” star Pamela Adlon, who started doing voice-over work at age 9 and played Bobby on “King of the Hill” for 13 seasons. “You have to be willing to be crazy and fail. That’s a huge discipline.”

Signing A-listers

Finding just the right “crazy” can be as challenging as casting a live-action series. Seth MacFarlane, who conjured up “Family Guy” and “The Orville,” said he often prefers sketch comedians such as Alex Bornstein to veteran voice-over artists, because they’re more likely to offer fully developed characters.

“I’m always looking for something a little more than a funny voice. I’m looking for a person,” he said. “ ‘The Simpsons’ really redefined the approach. Homer is a whole personality.”

In the early days of animation, actors who specialized in three-dimensional characters used to take a back seat to studio pros such as Mel Blanc, the voice of Bugs Bunny, Porky Pig and Barney Rubble. That all changed when Robin Williams signed on as the Genie in 1992’s “Aladdin,” a tour-de-force performance that generated Oscar buzz. Big names including Tom Hanks, Cameron Diaz and Steve Carell have followed him into the sound booth.

“Almost all the people who are great actors are great at voice-over work,” said “Simpsons” executive producer Al Jean, who recorded Daniel Radcliffe, Glenn Close and Martin Short this past season. “You’ve got to do a little more work when they’re not actors. Elon Musk [a recent guest on the show] may be the smartest person in the world, but he’s not a great voice-over actor. But he was very nice.”

It doesn’t hurt that the payday can be enormous. Reese Witherspoon scored a reported $10 million for 2009’s “Monsters vs. Aliens.” Each principal cast member of “The Simpsons” pockets $300,000 an episode. Billy West, best known for “Futurama” and “The Ren & Stimpy Show,” has an estimated net worth of $35 million.

But the average voice-over artist can’t rely solely on studio work to pay the bills. According to Global Voice Acting Academy, an online school, session fees average around $1,000 for up to four hours. That’s a nice chunk of change — but only if you’re in steady demand.

Opportunities are scarce in the Twin Cities. Part of Amazon’s Emmy-winning animated series “Danger & Eggs” was recorded in downtown Minneapolis, but the cartoon’s biggest name, “SNL’s” Aidy Bryant, contributed her parts from New York.

Sparkhouse, a Minneapolis-based company that promotes religious beliefs through animated shorts, usually pays $60 an hour. “We know that’s peanuts,” said Aaron Christopher, head of the video department at the nonprofit, whose regulars include Brave New Workshop cast member Taj Ruler. “But so many actors who grew up on cartoons thank me for the chance. They’re getting to live out a dream.”

That’s exactly how Nancy Cartwright feels. As the voice of Bart Simpson, she’s most likely saved enough money to tell the business to “get bent.” Don’t expect that to happen anytime soon.

George O’Hanlon was doing George Jetson until he was 76. Mel Blanc was working into his 80s,” said Cartwright, who shared the first Emmy ever given for voice-over performance with her castmates in 1992. “That’s how I see myself. I just want to keep doing it.”