Visual–Spatial Influences on Vocal Intensity: Effects of Speaker-to-Listener Distance and Room Size in Immersive Virtual Reality

OBJECTIVES: The aim of this study was to investigate the effects of speaker-to-listener distance versus room size on individuals' voice perception and production using immersive virtual reality (IVR). METHOD: Fifteen vocally healthy participants completed three speaking tasks: sustained vowel /a/, the standardized phrase "We were away a year ago," and spontaneous connected speech in nine randomly ordered IVR conditions. Conditions varied in room size, speaker-to-listener distance, and combinations of room size × speaker-to-listener distance. Auditory feedback remained constant across all trials to isolate the effects of visual input. Voice recordings were collected for subsequent analysis of sound pressure level (SPL) measurements for each condition and speaking task. RESULTS: SPL varied significantly as a function of speaker-to-listener distance, with farther listener distances associated with greater vocal intensity. Also, room size showed a significant effect, and a significant Room Size × Speaker-to-Listener Distance interaction indicated that the magnitude of the distance effect differed across room size. Overall, the pattern of findings suggested that listener distance cues were the primary driver of SPL modulation, with room size modulating the magnitude of these distance-related adjustments. CONCLUSIONS: This study demonstrates the importance of visual input in vocal regulation, with speaker-to-listener distance emerging as the primary factor influencing vocal intensity and room size serving as a moderating variable. These results carry important implications for voice training and therapy, emphasizing the need to integrate ecologically valid visual contexts-such as IVR environments that manipulate listener distance-to foster functional voice use and promote generalization beyond the clinical setting.