This week I have a story over at National Geographic News about curtains of air bubbles being used to attenuate the energy of sound waves created by undersea oil exploration and extraction:
“When a pressure wave hits an air bubble, it will compress the bubble, then it will expand again, so energy is lost,” Abbott explained. Although scientists disagree on the amount of energy lost in this process, Abbott said, there is no doubt that the air bubble actually changes the shape of the wave.
“Sound travels faster through water than air,” said Abbott. “It slows down as it hits the air bubble.” This creates a much smoother wave, altering it from a brief percussive bang to a longer, weaker wave.