A Positional Infrared Tracking System Using Non-individualised HRTFs to Simulate a Loudspeaker Setup and Its Influence on Externalisation of Music

Many artists produce and mix their virtual reality, game, or screen media audio productions only with headphones, but deploy them to stereo or multi-channel loudspeaker setups. Because of the acoustical and perceptual differences, listening on headphones might sound very different compared to loudspeakers, including the perception of sound sources inside the head (externalisation problem). Nevertheless, by using Head Related Transfer Functions (HRTFs) and accurate movement tracking, it is possible to simulate a loudspeaker setup with proper externalisation. In this paper, an infrared-based positional tracking system with non-individualised HRTFs to simulate a loudspeaker setup is conceptualised, designed and implemented. The system can track the user with six degrees of freedom (6-DOF); an improvement over current commercial systems that only use 3-DOF tracking. The system was evaluated on 20 participants to see if the additional DOF increased the degree of externalisation. While tracking increased the externalisation in general, there was no significant difference between 3-DOF and 6-DOF. Another test indicated that positional movement coupled with positional tracking may have a greater effect on externalisation compared to positional movement coupled with only head movement tracking. Comparisons between these results and previous studies are discussed and improvements for future experiments are proposed.