Choirmaster Gareth Malone joins forces with the BBC Singers to explore the styles and techniques that create a choir. He finds out why there are four sections, what polyphony is, what links Bach and the Beach Boys, what difference the venue makes and which choral combination is guaranteed to touch an emotional chord. With repertoire ranging from Mahler to Queen and contributions from leading experts, the programme lifts the lid on the secrets of choral music.