The ocean depths have become a noisy place. The causes are human: the sonar blasts of military exercises, the booms from air guns used in oil and gas exploration, and the whine from fleets of commercial ships that relentlessly crisscross the global seas. Marine experts say the rising clamor is particularly dangerous to whales, which depend on their acute hearing to locate food and one another. To fight the din, ... the National Oceanic and Atmospheric Administration seeks to document human-made noises in the ocean and transform the results into the world's first large sound maps. "It's a first step," Leila T. Hatch, a marine biologist and one of the project's two directors, said of the sound maps. "No one's ever done it on this scale." Michael Jasny, a senior policy analyst with the Natural Resources Defense Council, [which] has sued the Navy to reduce sounds that can harm marine mammals, praised the maps as "magnificent" and their depictions of sound pollution as "incredibly disturbing." Legal experts say the new findings are likely to accelerate efforts both domestically and internationally to deal with the complicated problem through laws, regulations, treaties and voluntary noise reductions. The Navy estimates that blasts from its sonars - used in training and to hunt enemy submarines - result in permanent hearing losses for hundreds of sea mammals every year and temporary losses for thousands. All told, annually the injured animals number more than a quarter million.