Is noise pollution killing whales and dolphins?

Humans create a lot of noise in the ocean - from sonar and seismic exploration, to pile driving when building wind farms. But how might this affect sealife?

Dr Maria Morell, from University of Veterinary Medicine Hannover, studies the ears of beached dolphins and whales to try and work out if hearing damage led to their death. She’s developed a new way of finding out if a cetacean's hearing was affected just hours before they beached, to support the theory that the two might be connected - and help pinpoint human activities that may be having an impact.