I want to create a browser-based crowd simulation demo: the scene is a busy street, with a high-angle camera that slowly cruises along the street, gliding past the crowd. The visuals should have a collage-style look with low-fidelity character silhouettes; realism is not the goal, but it should render hundreds to thousands of pedestrians while remaining smooth. Please implement it with Babylon.js and use optimization strategies suitable for large numbers of objects (e.g., the Solid Particle System (SPS) or mesh instancing) to draw the pedestrians; keep an orbit/cruise camera perspective. Also integrate Web Audio and, based on the distance between the camera and the crowd, implement 3D spatialized ambient noise so the crowd noise varies naturally with distance and position. Provide a directly runnable example and key parameters to help me verify performance and visual results.