It isn’t just the way Foxx’s voice alters in pitch and speed (he’s already discussed the common mistake of going the high-pitched Mickey Mouse route, whereas Tyson’s voice “is lower in tone when he’s actually speaking”). It’s also his mannerisms, the way he squints his eyes, hunches his shoulders, and pushes back his neck as if he’s on a swivel—ready for a punch or facing down a bank of cameras at a press conference.

He does it again when he shows you a Bill Cosby so unnervingly perfect you half expect him to start hawking Jell-o Pudding Pops or issuing warnings about the effects of Ebonics and rap music on the youth. In fact, the longer you sit with Foxx in the soundproof music room of his Tarzana, California, pad (amid a professional-quality recording studio setup) and listen to him talk about Quincy Jones, Michael Mann, Al Pacino, and Oliver Stone, the more you realize that Jamie Foxx’s ears, and not his exuberant charm, are his greatest asset as an actor.

The 36-year-old alumnus of In Living Color has already earned acclaim for his dramatic work in Any Given Sunday and Collateral, and for playing such real-life figures as Muhammad Ali’s cornerman Drew “Bundini” Brown (in Ali) and convicted killer Stan “Tookie” Williams (in the TV movie Redemption). But this fall he tackles an icon, the late Ray Charles, in a performance that has been generating Oscar buzz for months.

“My thing was not to do the ‘impersonation’ of Ray Charles,” says Foxx, whose neatly pressed black T-shirt bears an image of the rhythm and blues legend. “My thing was to do Ray Charles how he orders his food. Do Ray Charles how he talks to his kids. Do Ray Charles when he’s scared. When he’s angry—not yellin’ at you, just pissed off. Do Ray Charles how things roll off his back.”

What’s even more remarkable is that the transformation of Foxx’s career almost didn’t roll forward.