Transmission of music

A circuit is built on a stage: from an MP3 player, a cable goes to the beginning of a human chain. Here the current flows further into an active loudspeaker and from there back via a long cable to a MP3 player. When all people hold hands, music can be heard that immediately becomes silent when two people release their hands from each other.
The experiment uses harmless voltages and currents. It works because the human resistance is low due to its water and salt content and so humans can conduct electrical currents well.