The band recorded each of the eight album tracks in a different US city and frontman Dave Grohl reveals he approached songwriting differently this time - interviewing musicians from each place and using their quotes in the the tracks.

He explains: "The process is we come to a city and spend a week and record an instrumental because I interview all of these different musicians. I talk about the regional relevance of the music from that city, the cultural influence that made for the sound of the music.

"There's no way that you can tell the history of a city's music in one hour, so we have to do it in a way that relates to the band and goes from point A to point B and becomes a song."