In “DTF St. Louis,” David Harbour goes quiet.

The 51-year-old New York-born actor plays Floyd, a performance built around four months of daily American Sign Language practice. The work earned him his first Emmy acting nomination since 2017 — and his first in the limited series category, this time as an executive producer through his production company, Bravo Axolotl, the banner he founded in Dec. 2022.

“I spent about four months before the shoot just daily practice with a woman in New York and also someone in Atlanta, and I got to the point where I could definitely have conversations,” Harbour tells Variety. “It’s beautiful. I’d like to pick it up again; I just got real busy and I put it down.”

Learning the language, he says, rewired something in his brain. “In French, I’ll listen to the English and then interpret how I say it,” he says. “With sign language, you do get to the place where it becomes a different piece of your brain.”

For an actor who has made a career out of his physicality, playing a character who is contained and mostly still presented a different kind of challenge — one Harbour says came easier than expected.