Standing in a virtual-reality lab at the University of Maryland here, Ramani Duraiswami passed around a standard pair of headphones.
Music played over them — but to the wearer, the source of the sound seemed to move around the room. As the music quieted down, it sounded as if it came from farther away. As it got louder on one side of the headset, it sounded as if it came from that side. “We’re able to perceive the world in all dimensions using our ears,” said Mr. Duraiswami, a computer-science professor and co-founder of the start-up company VisiSonics.