Towards the Perception of Sound Source Directivity Inside Six-Degrees-of-Freedom Virtual Reality

Sound source directivity is a measure of the distribution of sound, propagating from a source object. It is an essential component of how we perceive acoustic environments, interactions and events. For six-degrees-of-freedom (6-DoF) virtual reality (VR), the combination of binaural audio and complete freedom of movement introduces new influencing elements into how we perceive source directivity. This preliminary study aims to explore if factors attributed to 6- DoF VR have an impact on the way we perceive changes of simple sound source directivity. The study is divided into two parts. Part I comprises of a control experiment in a non-VR monaural listening environment. The task is to ascertain difference limen between reference and test signals using a method of adjustment test. Based on the findings in Part I, Part II implements maximum attenuation thresholds on the same sound source directivity patterns using the same stimuli in 6-DoF VR. Results indicate that for critical steady-state signals, factors introduced by 6-DoF VR potentially mask our ability to detect loudness differences. Further analysis of the behavioral data acquired during Part II provides more insight into how subjects assess sound source directivity in 6-DoF VR.