Data from: Distributed acoustic cues for caller identity in macaque vocalization

Individual primates can be identified by the sound of their voice.
Macaques have demonstrated an ability to discern conspecific identity from
a harmonically structured ‘coo’ call. Voice recognition presumably
requires the integrated perception of multiple acoustic features. However,
it is unclear how this is achieved, given considerable variability across
utterances. Specifically, the extent to which information about caller
identity is distributed across multiple features remains elusive. We
examined these issues by recording and analysing a large sample of calls
from eight macaques. Single acoustic features, including fundamental
frequency, duration and Weiner entropy, were informative but unreliable
for the statistical classification of caller identity. A combination of
multiple features, however, allowed for highly accurate caller
identification. A regularized classifier that learned to identify callers
from the modulation power spectrum of calls found that specific regions of
spectral–temporal modulation were informative for caller identification.
These ranges are related to acoustic features such as the call’s
fundamental frequency and FM sweep direction. We further found that the
low-frequency spectrotemporal modulation component contained an indexical
cue of the caller body size. Thus, cues for caller identity are
distributed across identifiable spectrotemporal components corresponding
to laryngeal and supralaryngeal components of vocalizations, and the
integration of those cues can enable highly reliable caller
identification. Our results demonstrate a clear acoustic basis by which
individual macaque vocalizations can be recognized.