Bottlenose dolphins don't just whistle, click, and screech. They call themselves by name and recognise each other's names, too. Or, so says a recent study.
A team of scientists synthesized a series of bottlenose dolphins' signature whistles, and then called out to other dolphins through an underwater speaker system. The synthesised 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, even as they largely ignored the whistles of unknown dolphins.
The study clearly 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.