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 sea life?
Thousands of whales and dolphins die every year after becoming stranded on beaches.
Dr Maria Morell, from University of Veterinary Medicine Hannover, studies their ears 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 pinpoint human activities that may be having an impact.
Video by Jennifer Green, interview by Melanie Brown.