Individual Variation in Vocal Tract Resonance May Assist Oilbirds in Recognizing Echoes of Their Own Sonar Clicks
Oilbirds, Steatornis caripensis, live in colonies in caves, within which they navigate by echolocation (Griffin 1953, Snow 1961). The sonar “clicks” of these nocturnal birds typically last about 40 to 80 ms and are emitted at repetition rates up to about 12/s. Most of the acoustic energy lies beween 1 and 15 kHz. Sound during some clicks is continuous but other clicks, here referred to as double clicks, are divided by a silent period lasting about 20–30 ms into two brief bursts of sound.
KeywordsFormant Frequency Vocal Tract Silent Period Fundamental Resonance Bilateral Asymmetry
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