Refraction

Acoustic refraction is the bending of sound waves as they pass through regions of varying propagation speed. In air, temperature gradients and wind cause refraction: sound bends toward cooler air (downward at night, upward during the day) and downwind. Refraction is primarily significant in outdoor acoustics and large enclosed spaces like atria or sports arenas where temperature stratification exists. Snell’s law governs the relationship between angles and propagation speeds across the boundary. In indoor room acoustics, refraction is generally negligible because air temperature is relatively uniform. However, in computational acoustic models for very large spaces, temperature gradients along ceiling heights may need to be accounted for, particularly when predicting long-distance sound propagation in industrial halls or transportation terminals.