Many animals use sounds to convey information. Humans use vocal labels forobjects and for people. We call these words are names. Afew creatures such as dolphins and parrots can learn specific vocal labels and wilddolphins are known to have particular individual signature whistles.

　　Scientists at Scotland's St.Andrews University want to know these whistles be used as labels. The researchers analyze sounds from dolphins of Scotland's east coast and extract these signature whistles. Then they alter the sounds so the course wouldn't sound exactly like the original dolphin. They play those sounds back to the dolphins along with whistles form dolphins familiar to the animals and whistles from strangers. When the dolphins heard their own signature whistle, they routinely responded with that same sound. Their reaction only happen twice when they heard sounds from their pals, and not at all when they heard the alien dolphin.

　　The reserchers are proceeding with the National Academy of Sciences. The researchers think dolphins' signature whistle serve as self-identification and maybe even as a label for addressing each other, just like a name.