Later on in this unseasonably mild August night, on Lolla's towering Grant Park stage, Chance the Rapper will pause during his anti-record-label anthem "No Problem" and let the audience finish his signature line: "Countin' Benjis while we meetin', make 'em shake my other hand." At that precise moment, though, Maxey's hands will be signing the phrases "counting money" and "meeting," then miming a left-handed handshake followed by an emphatic middle finger. Maxey's ASL interpretation is an explosive, code-switching mishmash of textbook American Sign Language, pantomime, and makeshift signs he's cobbled together for slang words native to hip-hop ("molly," for example, combines gestures for "pill" and "sex"); the way he signs is as worldly and wry and improvisational as he is.

Clayton Hauck for GQ Clayton Hauck

And there's a reason for that: Although he's had profound hearing loss his whole life ("Whatever hearing is still left right before you're completely deaf, that's severely profound hearing loss," he explains) and is now one of the most visible people in his profession, Maxey didn't learn sign language until he was 18.

Matt Maxey was outfitted with hearing aids at the age of two, after his occupational-therapist grandmother noticed his hearing seemed off. Maxey learned to speak with the help of speech therapists, and at school, his teachers simply spoke into a microphone that transmitted directly into his two hearing aids. ("What they didn't know is that I was turning mine off," he says with a laugh.) So Maxey didn't begin learning to sign until he enrolled at Washington, D.C.'s, Gallaudet University, the world's only university for the deaf and hard-of-hearing.

Which wasn't a positive experience at first. "I never really knew about deaf culture," Maxey says. "All I knew was talking. I never signed. And they would always get mad at me; I could talk and they couldn't. It became kind of a hostile environment." Growing up in Atlanta, Maxey was exposed from an early age to hip-hop. So at night in his dorm room, Maxey practiced his sign language along with the lyrics of his favorite musicians—like J. Cole and Kendrick Lamar—and in 2010, at the urging of a friend, he uploaded to YouTube a video of himself signing along to Lil Jon & the East Side Boyz's "One Night Stand."

("One-night stand," for what it's worth, comes out to something more like "one-night fuck" in sign language. "Signing 'stand' doesn't make sense. You're not standing up," Maxey explains, then chuckles. "Well, you may be standing up.")

Maxey later dropped out of Gallaudet. Over the next few years, he worked as a pizza-delivery driver, a mobile-car detailer, and a UPS unloader in Jacksonville, Florida, and attended a few classes at a community college. But his sink-or-swim immersion in deaf culture continued out of necessity: Around 2013, his hearing aids stopped working, and he remembers with a laugh that at the time he was too broke to fix them. He kept making videos, though, learning new song lyrics by turning the volume all the way up in his earbuds—and last summer, his ASL video for DMX's "How's It Goin' Down" went viral after it surfaced on Reddit.

Around the same time, Maxey reached out to Kelly Kurdi—a Houston-based hearing sign-language interpreter who'd also released some music-translation videos on YouTube—to ask if she'd like to do a music video together. Several videos and one new friendship later, Kurdi and Maxey founded DEAFinitely Dope, a performance group dedicated to helping deaf and hard-of-hearing fans enjoy live shows. The Starkey Hearing Foundation contacted Maxey shortly afterward and outfitted him with Bluetooth-enabled hearing aids that connect to his iPhone and iPad and can play music right into his ear like an earbud.