Grohl tells Rolling Stone: "I'm a music nerd but I'm not a musicologist - I love talking about music and hearing stories, but I also love not knowing everything. The interviews turned into conversations that turned into lessons.

"The intention was to inform people, not just tell them something they already knew. I'm sitting in front of Allen Toussaint, Cyril Neville or Dr John and they're telling me things I never knew; I think I have to do that to keep the tone genuine."