Echoes from Solid and Hollow Metallic Spheres
A very successful pattern recognition experiment has been carried out with a dolphin identifying a solid sphere versus a hollow one. Results suggest that the dolphin utilized a time difference cue to distinguish between the two spheres. A theoretical evaluation of the physics of the targets, involving a model of the dolphin sonar, has been carried out. The ensonifying signal follows the model of an elementary signal as proposed by Gabor, i.e. a harmonic signal with a Gaussian envelope. The numerical values of the 3 needed parameters are estimated from the sonar recordings of the live experiment. The target modelling of the sphere is done with the quantities inner-to-outer diameter, density of the metal, and longitudinal and transversal wave velocity. A good match between the computational model and the actual experiment shows up.
KeywordsHollow Sphere Dominant Frequency Solid Sphere Transversal Wave Sphere Material
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