To really pull it off you need to understand records in terms of their precise effects on an audience – you need to hear music in terms of its energy and feeling. All good DJs can distinguish fine nuances in music; they are sensitive to the complex set of emotions and associations that each song inspires, and they know exactly how each record’s style and tempo will impact on the room. This understanding is the foundation of the DJs’ improvisation, as they choose which record to play next.