Bubble Acoustics: from listening to the ocean to cleaning medical devices and fighting antimicrobial and antibiotic resistance.

The 44th Maurice Lubbock Memorial Lecture.
Naturally-occurring underwater bubbles are extremely powerful sources of underwater sound. They act as sources for the sound of a waterfall or a breaking ocean wave, when those features inject atmospheric gas underwater to form bubbles, which then ring like tiny bells. By understanding how bubbles make sound, we can listen to the ocean, and track the >1 billion tonnes of atmospheric carbon that transfers between atmosphere and ocean annually when ocean waves break and trap atmospheric gas under the sea.

Bubbles can also scatter and refract the underwater sound fields produced by other acoustic sources. This effect is exploited by whales and dolphins when they use sound for hunting, and provides us with new options when hunting for explosives or covert surveillance equipment.

The lecture closes by discussing the role that acoustic bubbles have in mitigating the ‘antibiotic apocalypse’, which by 2050 is predicted to be causing more deaths than cancer, and will have cost the world economy more than the current size of the global economy.