Seals and sea lions undergo hearing tests in Australian research

Australia's scientists have trained seals and sea lions to take hearing tests at Sydney's Taronga Zoo, hoping to better understand how human-made noise affects marine mammals.

Two sea lions and two fur seals learned to press a paddle whenever they heard a tone, receiving fish as a reward for correct responses. The study, reported on 9 October, found the animals were most sensitive to sounds around 3.2 kilohertz. Researchers say the results provide a starting point for assessing noise from ships, aircraft and coastal construction.

The findings are particularly important for the endangered Australian sea lion, whose population is estimated at just 12,000. These animals rely on hearing to communicate, find food, navigate and detect danger.

Lead researcher Christine Erbe, from Curtin University, said scientists first needed to establish which sounds the animals could hear before measuring their impact. The results could help guide environmental assessments and noise controls as maritime industries expand. Researchers now plan to investigate how underwater noise affects the animals' hearing and behaviour.