Investigating the after effect of head-tracked movement on externalization for varying sound sources in binaural synthesis.

Binaural audio reproduction aims to create a realistic auditory experience for the listener through headphones. However, front and rear sound sources are often internalized (perceived inside the head) rather than externalized (perceived outside the head). Previous studies have shown that large head movements can significantly improve externalization, and that this improvement can persist even after head movements have stopped. This study examined how head-tracked movements influence the perception of sound externalization depending on the nature of the sound sources. The stimuli consisted of a first ``head movement" part during which the participants had to either perform a head movement or stay still, followed by a "rating" part where they evaluated externalization without moving. The sound sources during the ``rating" part could be similar, slightly different, or very different from the source during the head movement part. Results demonstrated that head-tracked movements effectively heightened externalization perception for all types of sources immediately after the movement. The type of source (female voice, male voice, or pink noise) did not affect perceived externalization. These findings suggest that the externalization enhancement induced by head-tracked movement persists after the movement ends even when encountering a different sound source.