Comparison of directional selectivity of hearing in a beluga whale and a bottlenose dolphin

Hearing thresholds as a function of sound-source azimuth were measured in a beluga whale Delphinapterus leucas and a bottlenose dolphin Tursiops truncatus in identical conditions using the auditory evoked-potential method. In both the beluga whale and bottlenose dolphin, the receiving beam width narrowed with frequency increase. At all frequencies, the receiving beam was markedly wider in the beluga whale than in the bottlenose dolphin. In...