Jill Munger first heard about fish that make sounds while she was an undergraduate student. A veteran researcher told her about marine acoustics. "She described it in this really cool way: I get to spy on critters in the ocean, without disturbing them," said Munger, currently a marine ecology researcher at Oregon State University. "When you're a diver you disturb the wildlife as you swim through, so you don't get to witness what they are doing when you're not there." But passive acoustic monitoring offers an unadulterated soundscape.