A study on the asymmetric cylinder wall thickness difference discrimination by dolphins

Atlantic bottlenose dolphins (Tursiops truncatus) can effectively discriminate between water-filled cylinders with different wall thicknesses. The dolphins' performance may be particularly good when the cylinders are thinner. The dolphins' performance is also asymmetric, in that the discrimination accuracy is not equal when the target thickness increases and decreases by the same amount. Inspired by this, a finite element model is proposed here to mimic a dolphin actively transmitting sound to discriminate between targets using acoustic echoes. The waveforms and frequency spectra of acoustic echoes from a standard cylinder and comparison cylinders with wall thickness differences of ±0.3 mm were compared. The employed model simulations show good agreement with previous experimental measurements by Au and Pawloski [(1992). J. Compar. Physiol. A 170(1), 41–47]. Asymmetric arrival time shifts were found for the echo peaks and troughs with the same sequence numbers when the wall thicknesses were increased and ...