Can sound waves put out a fire?

The answer

Yes, low-frequency sound waves (around 30–60 Hz) can extinguish small flames by increasing air velocity near the fire, which separates the burning fuel from the oxygen it needs. DARPA-funded research at George Mason University demonstrated a portable acoustic extinguisher using bass sound waves. The pressure oscillations disrupt the thin boundary layer of hot gases that sustains combustion, effectively smothering the flame without water or chemicals.