Effects of Source Location, Loudness, and Understanding of Speech on Interpersonal Distance in a Virtual Environment

Perception of the ambient loudness affects feelings of interpersonal intimacy, while the voice loudness modulates the interpersonal distance. We aimed to test whether the interpersonal distance could be modulated by the ambient loudness as well as the loud speech emanating from a virtual human. Participants were asked to walk toward a virtual human with either the ambient sound or the virtual human's speech. We found that the interpersonal distance to the virtual human increased only when the louder speech was emitted from the virtual human's head irrespective of the understanding speech, while the walking time increased only when the ambient sound was louder, suggesting that the interpersonal distance is modulated by the virtual human's voice but not by the ambient loudness.