Body weight, length, and vocal tract length were measured for 23 rhesus macaques (Macaca mulatta) of various sizes using radiographs and computer graphic techniques. linear predictive coding analysis of tape-recorded threat vocalizations were used to determine vocal tract resonance frequencies ("formants") for the same animals. A new acoustic variable is proposed, "formant dispersion," which sh...

Vocal individuality is widespread in social animals. Individual variation in vocalizations is a prerequisite for discriminating among conspecifics and may have facilitated the evolution of large complex societies. Ring-tailed lemurs Lemur catta live in relatively large social groups, have conspicuous vocal repertoires, and their species-specific utterances can be interpreted in light of source-...

We report a case of an otherwise healthy 23-month-old boy who presented with nystagmus, head shaking, andabnormal posture suggestive spasmus nutans. Neuro-ophthalmologic exam revealed bilateral, low-amplitude, high-frequency, horizontal, disconjugate nystagmus that was more prominent in one eye along shaking and tilt or face turn. The rest the systemic physical examination were normal. Magnetic...