A startup company in the USA, Sonic Fire Tech, is using infrasound to extinguish fires. An acoustic duct mounted in the eves of a house emits 20 Hz and below audio that oscillates the air, hindering the combustion process, which subdues fire. One advantage using sound to extinguish fire is that there is no water or chemical damage to the object. The company also makes a back-pack portable acoustic generator that can be used to extinguish flames.
See the youtube video of their system: