Rob Paulsen and Kevin Michael Richardson spent some time with CBR TV's Kiel Phegley to discuss their work on Nickelodeon's animated "Teenage Mutant Ninja Turtles." The men who bring Donatello (Paulsen) and Shredder (Richardson) to life spoke on a wide range of topics, from the stress different roles place on their voice (who knew saying "Uhn!" and "Agh!" for fight scenes could be so taxing on your throat?), to the characters' legacy across several generations of fans, to the importance of having Shredder as the show's central antagonist.

The pair spoke specifically about the recent episode that brought the current TMNT cast face-to-face with their '80s cartoon counterparts, which, for Paulsen, meant revisiting an old friend, of sorts. The actor pulled double duty for the episode, providing not only the voice for his current character, but for '80s Raphael as well, whom he voiced for the original cartoon.

RELATED: /article/original-teenage-mutant-ninja-turtles-appear-nickelodeons-animated-series

"It was utter joy," the actor said of returning to his TMNT roots. "Being around the four original , or three original Turtles -- Barry Gordon and Townsend Coleman and Cam Clark -- is always just an absolute pleasure. They're lovely people, we keep in touch all the time... The coolest thing about the whole experience of essentially talking to myself was just this really solid reminder of what an incredibly successful franchise this is."

In "Trans-Dimensional Turtles," the modern Turtles -- Seth Green as Leonardo, Sean Astin as Raphael, Rob Paulsen as Donatello and Greg Cipes as Michelangelo -- found themselves transported to another dimension, where they meet their 1980s counterparts. The episode blended different types of animation to reflect the change in dimensions -- including a trip to one based on Kevin Eastman and Peter Laird's original TMNT comics.

"Teenage Mutant Ninja Turtles" airs Sundays at 11 a.m. ET/PT on Nickelodeon.