Effect of Emulated Head-Tracking for Reducing Localization Errors in Virtual Audio Simulation

Virtual audio simulation uses head-related transfer function (HRTF) synthesis and headphone playback to create a sound field similar to real-life environments. Localization performance is influenced by parameters such as the recording method and the spatial resolution of the HRTFs, equalization of the measurement chain as well as common headphone playback errors. The most important errors are in-the-head localization and front-back reversals. Among other cues, small movements of the head are considered to be important to avoid these phenomena. This study uses the BEACHTRON sound card and its HRTFs for emulating small head-movements by randomly moving the virtual sound source to emulate head-movements. This method does not need any additional equipment, sensors, or feedback. Fifty untrained subjects participated in the listening tests using different stimuli and presentation speed. A virtual target source was rendered in front of the listener by random movements of 1c-7deg. Experiments showed that this kind of simulation can be helpful to resolve in-the-head localization, but there is no clear benefit for resolving front-back errors. Emulation of small head-movements of 2deg could actually increase externalization rates in about 21% of the subjects while presentation speed is not significant.