Creation of a Biomimetic Model of Dolphin Hearing Through the Use of Evolutionary Computation

Niche exploitation by an organism cumulatively results from its existing adaptations and phylogenetic history. The biological sonar of dolphins is an adaptation for object (e.g. prey or obstacle) detection and classification in visually limited environments. Current biomimetic modeling of echo discrimination by dolphins emphasizes the mechanical and neurological filtering of the peripheral auditory system prior to central nervous system processing of echoes. Anatomical data from, and psychoacoustic and neurophysiological experiments performed on bottlenose dolphins (Tursiops truncatus) have determined the structure of auditory tuning curves for a few tested frequencies. However, an optimal filter set has yet to be developed that demonstrates comparable frequency-dependent sensitivity across the range of dolphin hearing. Evolutionary computation techniques are employed to optimize the sensitivity of filters to that observed in the bottlenose dolphin by seeding the population with bounded filter parameters and evolving the number, shape, and frequency distribution of individual filters. Comparisons of evolved and known biological tuning curves are discussed.