The idea that Will Smith speaks with an African accent in his new movie Concussion is a problem in and of itself.
There’s no such thing as an African accent. Ghanaians speak different pidgin English than Nigerians do, and Liberians’ intonations and cadences don’t sound anything like how the Congolese or the Senegalese speak English. All of this leads back to that pesky fact (which some Westerners have trouble grasping) that Africa is a continent, not a country. Every group puts its own spin on the King’s English.
Now, by the looks of the trailer, Will Smith did his thing in Concussion (wouldn’t it be cool if both he and Spike Lee got Academy Awards on the same night?). In Concussion, Smith plays real-life Nigerian-born physician Dr. Bennet Omalu, who discovered that two NFL players had severe brain disease as a result of the head bashings they endured while playing professional football.
Omalu was not only born in Nigeria but also went to college and medical school there before coming to the U.S. for additional schooling and to practice medicine (he also works as a college professor teaching medicine). So Smith needed to pick up the accent that Nigerians have when they speak English.
Source: The Root | DIANA OZEMEBHOYA EROMOSELE