A technique for giving more depth to traditional stereo sound. Typically, 3-D sound, or 3-D audio, is produced by placing a device in a room with stereo speakers. The device dynamically analyzes the sound coming from the speakers and sends feedback to the sound system so that it can readjust the sound to give the impression that the speakers are further apart.
3-D audio devices are particularly popular for improving computer audio where the speakers tend to be small and close together. There are a number of 3-D audio devices that attach to a computer's sound card.