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Speech Sounds and Features (MIT, Cambridge). The Acoustic Theory of Speech Production (Mouton, The Hague). “ Post-conflict reunions and reconciliation in long-tailed macaques,” Animal Beh. The Vowel: Its Nature and Structure (Tokyo-Kaiseikan, Tokyo). “ Social relationships and social cognition in nonhuman primates,” Science 234, 1361– 1366. “ The role of grunts in reconciling opponents and facilitating interactions among adult female baboons,” Animal Beh. How Monkeys See the World (University of Chicago, Chicago).
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“ Assessment of meaning and the detection of unreliable signals by vervet monkeys,” Animal Beh. “Recognition of individuals within and between groups of free-ranging vervet monkeys,” Am. “ Vocal recognition in free-ranging vervet monkeys,” Animal Beh.
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“Contributions of fundamental frequency, formant spacing, and glottal waveform to talker identification,” Unpublished doctoral dissertation, Indiana University. Canary: The Cornell Bioacoustics Workstation, Version 1.1 (Cornell Laboratory of Ornithology, Ithaca, NY). “ Modes of vocal variation in Syke’s monkey ( Cercopithecus albogularis) squeals,” J. “Coo’ vocalizations in stumptailed macaques: A controlled functional analysis,” Behavior 119, 143–160. “Frequency code: Orofacial correlates of fundamental frequency,” Phonetics 44, 173–191. “Acoustic cues to gender and talker identity are present in a short vowel segment produced in running speech,” Psych. Elements of General Phonetics (University of Chicago, Chicago). Implications of these findings for vocal production mechanisms in nonhuman primates and previous studies of rhesus monkey vocalizations are discussed. This result was strikingly different from the corresponding outcome of a previous test with coo calls, but consistent with the acoustic analysis. Playback experiments conducted with the screams showed no response differences when listening animals heard vocalizations produced by kin or nonkin individuals. Noisy screams (continuous, broadband noise bursts that could include a high-frequency, periodic component) could not be reliably sorted by caller. Grunts (pulsed, noisy calls) were classified at lower, but above-chance rates and spectral patterning cues were again critical in this sorting. Results showed that coos (rich, harmonically structured sounds) were markedly more distinctive by caller than were either grunts or noisy screams, and that spectral-patterning measures related to vocal tract filtering effects were the most reliable markers of individual identity. Vocalizations were then classified by caller identity, based on discriminant function analyses. First, acoustic analyses were used to characterize spectral patterning, the fundamental frequency, and temporal characteristics of these three distinct call types. In order to systematically test whether acoustic cues to identity are reliably present across the vocal repertoire of rhesus monkeys ( Macaca mulatta), we examined coos, grunts, and noisy screams produced by adult females of two free-ranging groups.
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The importance of individual identity and kinship has been demonstrated in the social behavior of many nonhuman primates, with some evidence suggesting that individually distinctive acoustic features are present in their vocalizations as well.
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