John DiMaggio

You can say this about voice-over actors: They love to talk. One hundred and fifty of Hollywood's busiest performers and casting agents from the often overlooked industry enthusiastically share their stories in the new documentary I Know That Voice, available on VOD platforms and at iTunes starting Tuesday.

Director Lawrence Shapiro was inspired to make the film when he saw how animated (pun intended) fans became when meeting his friend John DiMaggio, voice of the curmudgeonly-yet-beloved robot Bender on Futurama. "I'll admit it, applause is great," says DiMaggio, one of the industry's most popular and prolific stars, whose résumé also includes roles on Adventure Time, The Penguins of Madagascar and Kim Possible. But outside of fan-centric events like Comic-Con, voice actors work in relative obscurity, which motivated DiMaggio to sign on as producer. "I want my peers to get a little bit of recognition. These are some of the most talented people I know, and some of the most brilliant character actors that I know."

As great as adulation can be, it's clearly not a primary motivation for voice actors (unlike many of their live-action counterparts). "We love what we do so much that we don't need that ego stroke," DiMaggio says. "The work is that that much fun, and there's so much creativity, and crafting and real character work that we don't really need anybody telling us how great it is." Plus, he adds with a laugh, "We get paid for what we used to get in trouble for doing. I sometimes compare the voice director to being the substitute teacher."

The film emphasizes that these vocal gymnasts are, first and foremost, actors. A good Christopher Walken impersonation will only get you so far in the business, while the most successful voice actors have mastered the ability to convey every possible emotion without the benefit of facial cues. "They have to get every cryptic expression that you would do on camera, on mic," voice director Ginny McSwain says in the film. "They're storytellers, that's their gift."

Among those interviewed are Tom Kenny (the voice of SpongeBob SquarePants), Janet Waldo Lee (Judy Jetson from The Jetsons), June Foray (Rocky and Bullwinkle's Rocky) and Nancy Cartwright (Bart Simpson). There are also appearances by several live-action stars who have done crossover work in animation and video games, including Mark Hamill, Diedrich Bader, Seth Green and Happy Days icon Marion Ross, who admits that playing SpongeBob's grandmother "turns out to be one of my best credits."

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