Signal processing by echolocating dolphins

Abstract

Many different types of target discrimination experiments have been performed with echolocating dolphins in order to understand and model their echolocation capabilities. However, not many experiments have been performed that measured differential performance as a function of the magnitude of a single target variable, thus making it very difficult to extract limits of various auditory discrimination capabilities. Nevertheless, sufficient information exists that could provide some insight on important echo cues utilized by dolphins and what the signal processing may be. Furthermore, other types of experiments emulating some dolphin experiments have also been conducted. Stretched versions of echoes from target used in dolphin experiments have been used in human listening experiments to determine salient cues present in the echoes. Neural network experiments have also been conducted using echoes from the same target used in the dolphin experiments. The most pertinent of these experiments involving dolphins, humans, and neural networks will be discussed in order to gain insight into important target cues and the manner in which these cues might be processed by echolocating dolphins. The discussion will be conducted in light of the results of a recent experiment in which the auditory filter shape of a dolphin for different frequencies was determined.