Many animals use sounds to convey information. Humans use vocal labels for objects and for people. We call these words, and names. A few creatures, such as dolphins and parrots, can learn specific vocal labels. And wild dolphins are known to have particular, individual signature whistles. Scientists at Scotland’s St. Andrews University wanted to know: can these whistles be used as labels? The researchers analysis sounds from dolphins off Scotland’s east coast, and extracted these signature whistles. Then they altered the sounds so the calls wouldn't sound exactly like the originating dolphin. They played those sounds back to the dolphins, along with whistles from dolphins familiar to the animals and whistles from strangers. When the dolphins heard their own signature whistle they retainly responded with that same sound. That reaction only happened twice when they heard sounds from their pals and not at all when they heard the alien dolphin.