Whether it is used to help find prey or to avoid predators, sound is key to survival for many vertebrates. On land, the direction from which a sound originates can readily be determined by gauging the time delay and intensity variation between each ear. Underwater, that is much harder. In this week’s issue, Benjamin Judkewitz and colleagues affirm how fish achieve this feat. Working with the small, transparent fish Danionella cerebrum (a stained specimen of which is pictured on the cover), the researchers carefully controlled pressure and particle motion in the water, and imaged sound-induced vibration inside the fish. The team found that, in line with one of several considered hypotheses, the fish compare pressure and particle motion signals to detect the direction of sound sources.