Category Justification

The funding proposed here will provide an apparatus for precisely displaying 3D sounds, advancing understanding of how humans use sound to locate sources and analyze their environment, and exploring how audition affects and is affected by vision. Specifically the proposed research aims to answer the complementary questions • What information is used to locate the source of a sound within a listener’s environment? • What information about a listener’s environment can be derived by listening to sounds from a known source (e.g. room-size)? • How do (possibly incongruent) visual and auditory information interact to determine perception of the environment? Proposed here is an automated apparatus capable of precisely placing a sound source at any location on a sphere of 1 meter radius around the head of a listener quickly, accurately, and automatically and the means to control sound propagation within the laboratory. Present State of Knowledge The sense of audition converts pressure waves at the ears into detailed information about the locations, timing, and material properties of events in our environment. This information then interacts with information from the other senses (e.g. vision and touch) to yield our rich perceptual world. While much is known about the process of sound transduction, higher level auditory perception (called scene analysis) of world properties like 3-D source localization, room size inference, and material property inference are poorly understood. Even less is known about its interaction with other senses. Much of the problem is due to the difficulty of the required experiments. Higher level audition experiments require controlling the sound arriving at the ear while preserving the information contained in sounds from natural environments. Natural sound sources and natural sounding displays (such as speakers) are rich in information, but difficult to control. On the other hand, easily controllable displays (headphones) suffer from poor localization, externalization, and acoustic performance. In order to conduct meaningful experiments into auditory scene analysis, a precisely controllable headphone-free auditory display is needed.