At high wing angles, why can an owl's front-edge combs make airflow quieter?

Answer: Control steep airflow

Sharpen the wing edge — A sharper edge sounds plausible because knives cut cleanly, but wings are not knives. At steep angles, the danger is that air changes suddenly around the upper surface and forms noisy, draggy structures. Owl-like serrations act more like flow-control teeth than blades. They disturb the flow early so the later breakup is less severe.

Control steep airflow ✓ — Right. The comb-like leading edge is best understood as passive flow control at high angles of attack. It is counterintuitive because a rough edge can be quieter than a sleek edge when it manages the transition from smooth to turbulent flow. Engineers study this for blades because the best shape depends on angle and speed, not on looking clean.

Trap air under feathers — Trapping air under feathers points to the wrong part of the wing. The front comb sits where incoming air first meets the wing, so studies frame its role as controlling that incoming flow around the leading edge. A storage-pocket idea does not explain why the effect changes with angle of attack. The useful lesson is timing: nudge the flow early before the loud breakup develops.