A beluga was tested to label objects using vocal symbols in order to form a bidirectional relationship between the visual symbols and sounds. In the Training session, the subject was first trained to distinguish four objects by four separate calls that he made. He learned to emit different calls corresponding to the sample stimuli. Next, these three recorded calls were played back to the subject, and he was required to select the objects (comparative stimuli) corresponding to the presented

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... . He succeeded in correctly choosing the objects corresponding to the sounds played back. In the Test session, when a completely new recorded sound was presented to the subject, he could choose the correct object by matching the sample sound with the object. It is suggested that a beluga have realized bidirectional relationships or symmetrical relationship between visual symbols and sounds. This is a preliminary study that shows both production and comprehension of symbols in marine mammals. Study of artificial language is one of the approaches used to investigate animal cognition, and teaching artificial language to animals plays an important role in the burgeoning of research in comparative animal cognition. Research on teaching language has been conducted on chimpanzees