Acoustic features of objects matched by an echolocating bottlenose dolphin.
The focus of this study was to investigate how dolphins use acoustic features in returning echolocation signals to discriminate among objects. An echolocating dolphin performed a match-to-sample task with objects that varied in size, shape, material, and texture. After the task was completed, the features of the object echoes were measured (e.g., target strength, peak frequency). The dolphin's error patterns were examined in conjunction with the between-object variation in acoustic features to identify the acoustic features that the dolphin used to discriminate among the objects. The present study explored two hypotheses regarding the way dolphins use acoustic information in echoes: (1) use of a single feature, or (2) use of a linear combination of multiple features. The results suggested that dolphins do not use a single feature across all object sets or a linear combination of six echo features. Five features appeared to be important to the dolphin on four or more sets: the echo spectrum shape, the pattern of changes in target strength and number of highlights as a function of object orientation, and peak and center frequency. These data suggest that dolphins use multiple features and integrate information across echoes from a range of object orientations.
Hawaii Institute of Marine Biology, P O. Box 1106, Kailua, Hawaii 96734, USA. Caroline_Delong@Brown.edu
Caroline M
CM
Delong
Whitlow W L
WW
Au
David W
DW
Lemonds
Heidi E
HE
Harley
Herbert L
HL
Roitblat
D000162:Acoustics; D000818:Animals; D050681:Bottle-Nosed Dolphin / Q000502:physiology*; D002755:Choice Behavior / Q000502:physiology; D016002:Discriminant Analysis; D004192:Discrimination, Psychological / Q000502:physiology; D004455:Echolocation / Q000502:physiology*; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D013018:Sound Spectrography