What Makes Virtual Crowds Feel Real? Sound, Sociality, and Movement in Virtual Reality

Realistic pedestrian dynamics are essential for enhancing presence and user engagement in immersive virtual environments (IVEs), yet most VR-based crowd research focuses primarily on basic locomotion or isolated pedestrian behaviors. To determine which scene-level and behavioral enrichments truly improve the VR experience, we built a modular pedestrian framework for a virtual shopping street, allowing the integration of ambient-sound layers, context-sensitive walking speeds, group dynamics, user-awareness cues, and environmental actions such as sitting, window-shopping, and shop entry. In a within-subjects study, thirtyone participants experienced five progressive conditions - starting with a baseline, then four incremental enrichments, the final one yielding the full system. Our findings reveal that incorporating diverse walking behaviors, contextual sounds, and social interactions significantly improved users' immersion; 90% of participants reported enhanced realism, particularly noting the positive effects of soundscapes and interactive behaviors on their overall experience. This research highlights the critical role of behaviorally rich crowd simulations for advancing VR applications and fostering deeper user engagement.