Sound is energy in the form of a wave. In the dark depths of the sea, whales and other marine mammals use gentle sound pulses to communicate about feeding, mating, and to keep their groups together.

But as humans increasingly plumb the ocean for their own forms of energy, the loud sounds of exploration, development, and construction send powerful waves that can confuse and harm even the mightiest denizens of the deep.

Offshore oil and wind power companies are studying an unusual but promising means of lessening the impact of sound on marine mammals: bubble curtains. Adapting a technique that proved successful in underwater bridge building, energy firms are testing the benefits of surrounding their operations with walls of bubbles that actually