An Exploration of Virtual Auditory Shape Perception

Abstract

Virtual reality may help us to understand and eventually extend the domain of auditory perception. Although sound sources are rarely point sources, in our natural environments acoustic and perceptual factors tend to de-emphasize the extended spatial properties of sound. In virtual environments it is possible to re-emphasize these properties. This paper explores precedents for auditory shape perception and tests some ideas about implementation with virtual environment technology.

A preliminary investigation was performed wherein subjects drew pictures of their impressions of two types of auditory shape displays. Later, a series of experiments were performed to examine auditory shape perception in more detail. In a screening experiment, subjects were selected for compatibility with a virtual auditory spatialization system based on the Crystal River Convolvotron(TM) and one specific head-related transfer function. Later experiments in the series examined the ability of subjects to recognize geometric shapes and alphanumeric characters presented by sequential excitation of elements in a "virtual speaker array." Subjects were able to identify the patterns with significantly better than chance accuracy. However, performance worsened with increasing numbers of pixels in the sequence which is a strong indication that the task was cognitively limited. The remaining experiment was performed using a time-independent display technique, but failed to produce recognition performance that was consistently better than chance.

These experiments have validated the use of virtual sound technology in auditory shape perception experiments, and have shown that virtual environments are viable alternative for the complex physical apparati that future work in auditory shape perception might otherwise require.