Millions of hedgehogs die as they cross the roads, but a discovery is paving the way for a warning that might stop them crossing at dangerous times.

Researchers describe an acoustic meta-surface that uses pingpong balls, with small holes punctured in each, as Helmholtz resonators to create inexpensive but effective low-frequency sound insulation.

Jake M Robinson is affiliated with the United Nations Framework Convention on Climate Change think tank Resilience Frontiers. He receives funding from the National Environmental Science Program for ...