Kaos Choir for Deaf and Hearing Children shot to fame when they performed at the opening ceremony of the Paralympic Games in 2012. The London-based choir bring together deaf children and hearing children, and all songs performed are both sung and signed by everyone to whatever ability they can.
Find out how it works as they prepare for one of their many Christmas performances.
See video
http://www.bbc.co.uk/news/magazine-35113096