Recognition and Classification of Noise Signals by Dolphins (Tursiops truncatus) Under Conditions of Noise Interference and Spatial Uncertainty of Their Simultaneous Presentation

The ability of the dolphin auditory system to recognize and classify noise signals according to certain invariant characteristics under the influence of noise interference and in conditions of spatial uncertainty of the simultaneous presentation of positive and negative signals was investigated. Bottlenose dolphins trained to differentiate such signals had to solve this problem in conditions simulating real sea conditions, when the perception of a useful noise signal occurs against a background of similar signals and against a noise interference background. First, noise signals were sequentially presented to the animal against a background of white masking noise. Subsequently, the dolphin had to identify a signal of a positive class from several simultaneously sounding sound sources. The animal’s performance was assessed at several specified noise interference levels. In this case, the actual noise interference was both white noise and simultaneously sounding negative signals. It has been shown that the efficiency and noise immunity of the dolphin’s auditory system depends on the degree of alternativeness of the spatial uncertainty of the simultaneous presentation of signals.