The Simulated Open Field Environment for Auditory Localization Research

Most research on auditory localization has been done in either a non-reverberant environment or using virtual acoustic space presented under headphones. The Simulated Open Field Environment (SOFE) uses computer controlled loudspeakers in an anechoic chamber to create realistic auditory scenes with simulated sources and echoes. Each approach has didsadvantages; for example the anechoic environment represents an unnatural listening condition, while head movements can have an impact on studies with virtual acoustics, and neither offers the subjective experience of immersion in a coherent auditory/visual spatial environment. A major upgrade of the SOFE now features 48 channels of parallel audio in addition to a projected high-resolution visual scene of 80. Together these provide 360of acoustic stimuli with a concomitant visual display. Use of such a large number of loudspeakers allows for higher resolution in simulating more complex environments, including multiple sources and reflections as well as auditory motion, and current work is directed toward still greater resolution through amplitude panning between speakers. Distancedependent damping as well as temporal delay is simulated for all auditory signals. Subjects mark perceived sound azimuths with a visual marker on the screen moved with a trackball. In another task they mark both the direction and distance of a sound by moving virtual visual sources in a 3-dimensional display of visual perspective.