Acquisition of Instruments to Measure Visual Bias of Occluded Auditory Signals in Three-Dimensional Space

Wake Forest University, Winston Salem NC

Investigators

Abstract

With support from a National Science Foundation Major Research Instrumentation Award, Wake Forest University's Department of Psychology will acquire stereovision equipment from Cambridge Research Systems and audio equipment allowing for head related transfer functions (HFTFs) and binaural-related impulse-responses (BRIRs) from Tucker-Davis Technologies. This equipment will be located in an audiometric sound chamber and designed to produce a three-dimensional audio-visual environment to measure the multisensory localization of visually occluded auditory signals. It is a custom design and the only one of its kind in the United States. Multisensory integration is typically studied with two-dimensional stimuli. Designing experiments in a three-dimensional environment is a novel approach and has the broader impact of allowing occluding objects to be added to the scene. This ecologically valid condition is the one most encountered in nature, allowing it to tap accurately the design underlying the human multisensory system. Recent advances in environmental acoustics and stereoscopic viewing technology offer an exciting opportunity to explore how an object's surface properties affect 3-dimensional auditory localization. How an object's opacity or transparency influences the extent to which flashes of light can bias the perception of where a sound burst originates has significant theoretical, physiological, and practical implications for the field of multisensory integration. The hypothesis that the opacity of an object constrains the extent to which a light can bias the perceived location of a sound will be tested for the first time. The results can potentially change how psychophysicists model auditory occlusion in 3-dimensional space. Current 2-dimensional models prevent exploring how the significant ecological constraint of occlusion affects auditory localization. Likewise, the results can change what neuroscientists consider to be the type of contextual factors that can influence the receptive field properties of multisensory neurons. In nature, receptive fields are seldom free of obstacles. The ways in which the qualities of such objects influence receptive fields will lead to a better understanding of receptive fields' organization. The results can also change how engineers design environments, such as cockpits, to account for how objects affect the accurate localization of sound sources. Thus, the ecological validity in studying the cross-modal processes of stereoscopic visual input and acoustical head-related transfer functions (HRTFs) to determine how surface properties affect sound localization will expand current theories of multisensory integration. The equipment will be used by multiple researchers, mostly psychophysicists and neurobiologists, at the professional, graduate and undergraduate level across two campuses (e.g., Wake Forest College of Art and Sciences, and Wake Forest University of Medicine's Department of Neurobiology and Anatomy).