Sound waves propagate at meters per second through air at C ( F). For comparison, light propagation is about 874,000 times faster. We have planes and cars that can surpass the speed of sound, but are nowhere near traveling at the speed of light. This is perhaps the most important difference between sound and light for making VR systems. The result is that human senses and engineered sensors easily measure differences in arrival times of sound waves, leading to stronger emphasis on temporal information.