The distorting sound of Greenwich foot tunnel
When the sound artist Peter Cusack asked people about their favourite sounds of London, the Greenwich tunnel was a popular answer because of the way it distorts voices.
Sound waves bounce back and forth across the width of the 1,215ft (370m) long tunnel, distorting voices using the same physics which make some people think they can sing well in a shower stall.
The clip is of the sound of a skateboarder passing by the microphone.
19 Dec 2012