Sound localization in chinchillas. II. Front/back and vertical localization.
The ability of chinchillas to make front/back and vertical locus discriminations was examined behaviorally using a conditioned avoidance procedure. Their minimum audible angle for localizing single broadband noise bursts was 36 degrees for front/back localization and 23 degrees for vertical localization. Sound localization tests using filtered noise demonstrated that the signal must contain high frequencies in order for chinchillas to make front/back and vertical locus judgements and that frequencies in their highest audible octave (i.e., above 16 kHz) contribute to localization. These results support the view that a major selective advantage of high-frequency hearing in mammalian evolution was its utility for monaural as well as binaural sound localization.
Heffner
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Department of Psychology, University of Toledo, OH 43606, USA. RHeffner@AOL.com
Heffner
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HE
Koay
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D000161:Acoustic Stimulation; D000818:Animals; D001309:Auditory Threshold / Q000502:physiology; D001362:Avoidance Learning / Q000502:physiology*; D002682:Chinchilla; D006316:Hearing Loss, High-Frequency / Q000503:physiopathology*; D008297:Male; D011601:Psychophysics; D013017:Sound Localization