The question is actually super easy to answer. Brittany Howard is the lifeblood of the song. Born in 1988, the singer and guitarist founded the Alabama Shakes together with her schoolmate Zac Cockrell in 2009. The song is about ongoing struggles in a relationship. The initial guitar riffs, which are cleanly and spatially divided by our soundbar, are interrupted by an incredible scream that heralds the actual start of the song.
Brittany Howard's performance in the video below is truly magnificent. With her stature and demeanor, she really is what you call a front woman. Simply cool.
In the meantime, Brittany Howard is focusing primarily on her solo career, in which she is also successful. If you want to find out a little more about her, you can listen to the following interview.