Because I’m Happpppy – But why do our favourite tunes make us smile?

‘I will wait’ by Mumford and Sons. Metallica’s ‘Seek and Destroy’, or perhaps ‘Can’t stand me now’ by the Libertines. Songs the crowd will be jumping to this weekend, but why do we turn the volume up for some songs and tune out to others? And what gives a performer the ‘rush’ they experience when taking to the stage in front of 50,000 people?