Researchers have known for years that individual bottlenose dolphins (and members of many other dolphin species, too) emit unique signature whistles using the nasal passages beneath their blowholes (here one). But until recently, no one knew whether the whistles actually convey identifying information, like the sounds that make up our names do.
To find out, a team of scientists synthesized a series of bottlenose dolphins' signature whistles, then called out to other dolphins through an underwater speaker system. The synthesized whistles lacked any features of an individual dolphin's voice--the same way a computer-generated version of your name would lack any features of your voice. Yet the dolphins often turned to listen when they heard the synthesized versions of their kin's whistles, and largely ignored the whistles of unknown dolphins.
No one's claiming that such signature whistles are equivalent to "Chuck" and "Edna." But the research suggests that dolphins do more than just recognize the tone of a familiar voice. They identify and respond to signature sound patterns even when a stranger whistles them. What's more, we now know that mother dolphins whistle their signature sound patterns--their "names"--to their babies following birth. In fact, they whistle them ten times more often than normal during a calf's early days, when it's most likely to get lost.
