The speed of vessels operating near where killer whales live is the most influential factor—even more so than size—in determining how much noise reaches the endangered animals.

Toddlers as young as two understand that the noises they make can affect people around them—and know how to adapt the loudness of the sounds they make depending on what they’re doing and where they are.

A new app that uses a smartphone to wirelessly test for sleep apnea may be able to detect whether your snoring is just annoying or a potentially life-threatening problem.