It is one of Earth's most haunting sounds - the "singing" of baleen whales like the humpback, heard over vast distances in the watery realm. Baleen whales - a group that includes the blue whale, the largest animal in Earth's history - use a larynx, or voice box, anatomically modified to enable underwater vocalization, researchers said on Wednesday. That means baleen whales make their sounds with their larynx, as do humans, while toothed whales - including dolphins, porpoises, killer whales and sperm whales - evolved a different mechanism employing a special organ in their nasal passages.