George Mason University electrical engineering undergrads Viet Tran and Seth Robertson have created a fire extinguisher prototype that uses low-frequency sound waves to put out a fire. Initially, both students thought big speakers and high frequencies would douse a fire. “But it’s low-frequency sounds -like the thump-thump bass in hip-hop that works,” says Tran. Their 20-pound prototype is free of toxic chemicals and eliminates collateral damage from sprinkler systems. If mounted on drones, it could improve safety for firefighters confronting large forest fires or urban blazes. Researchers at DARPA and West Georgia University are also working on similar concepts.