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TARGET DISCRIMINATION BY AN ECHOLOCATING FINLESS PORPOISE, NEOPHOCAENA PHOCAENOIDES
Author(s) -
Nakahara Fumio,
Takemura Akira,
Koido Takashi,
Hiruda Hisoka
Publication year - 1997
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.1997.tb00088.x
Subject(s) - porpoise , biology , human echolocation , zoology , fishery , computer science , harbour , programming language , neuroscience
A bstract The ability of a finless porpoise (Neophocaena phocaenoides) to discriminate the material and size of a target by echolocation was investigated. The porpoise was required to choose a standard target of a 15‐mm diameter solid steel cylinder from two stimuli, a standard and a comparison target, presented simultaneously. The porpoise could distinguish a standard cylinder from acrylic resin and brass targets, but had difficulties distinguishing it from an aluminum cylinder. In size discrimination, the porpoise could distinguish the standard from 12‐, 18‐, and 20‐mm diameter cylinders, but had difficulties distinguishing it from a 14‐mm diameter cylinder. Echo measurements suggest that the porpoise is able to detect: (1) time difference between two echo highlights to within approximately 1 μS, (2) frequency shifts of approximately 7 kHz in a broadband echo having a peak frequency of nearly 140 kHz, (3) time‐separation pitch of approximately 30 kHz, and (4) target strength differences of approximately 1 dB.