What is echolocation and what role does sound play in an underwater environment? Objective *How do marine mammals use sound? *What are the most common human-made sounds heard in the ocean? *How might vessel noise affect the behavior (feeding, diving, respiration, resting) of marine mammals? *Why is studying underwater acoustics important to the survival of marine mammals? Background Marine animals rely on sound to acoustically sense their surroundings, communicate, locate food, and protect themselves underwater. Some predators, like orcas (killer whales) and dolphins, use echolocation to find Duration: 60 Minutes.