Pulse register phonation in Diana monkey alarm calls

Abstract

The adult male Diana monkeys ͑Cercopithecus diana͒ produce predator-specific alarm calls in response to two of their predators, the crowned eagles and the leopards. The acoustic structure of these alarm calls is remarkable for a number of theoretical and empirical reasons. First, although pulsed phonation has been described in a variety of mammalian vocalizations, very little is known about the underlying production mechanism. Second, Diana monkey alarm calls are based almost exclusively on this vocal production mechanism to an extent that has never been documented in mammalian vocal behavior. Finally, the Diana monkeys' pulsed phonation strongly resembles the pulse register in human speech, where fundamental frequency is mainly controlled by subglottal pressure. Here, we report the results of a detailed acoustic analysis to investigate the production mechanism of Diana monkey alarm calls. Within calls, we found a positive correlation between the fundamental frequency and the pulse amplitude, suggesting that both humans and monkeys control fundamental frequency by subglottal pressure. While in humans pulsed phonation is usually considered pathological or artificial, male Diana monkeys rely exclusively on pulsed phonation, suggesting a functional adaptation. Moreover, we were unable to document any nonlinear phenomena, despite the fact that they occur frequently in the vocal repertoire of humans and nonhumans, further suggesting that the very robust Diana monkey pulse production mechanism has evolved for a particular functional purpose. We discuss the implications of these findings for the structural evolution of Diana monkey alarm calls and suggest that the restricted variability in fundamental frequency and robustness of the source signal gave rise to the formant patterns observed in Diana monkey alarm calls, used to convey predator information.

Perception of Male Caller Identity in Koalas (Phascolarctos cinereus): Acoustic Analysis and Playback Experiments

“…Because the spectral prominences of male koala bellow inhalation phases are relatively stable (see Figure 1b), and therefore consistent among the calls an individual makes, they are likely to be highly individually distinctive. In addition, observations of male bellow spectrograms and power spectra show a pulse-train structure that should emphasise characteristics of the supra-laryngeal filter (see Figure 1b), increasing their salience to receivers (as discussed by [39], [40], [41]). Accordingly, the pulse-train structure of male koala bellows may even have evolved to facilitate vocal recognition by highlighting a caller's distinctive formant pattern.…”

Campbell's Monkeys Use Affixation to Alter Call Meaning

“…Humans are able to control their larynx and vocal tracts rapidly and precisely by means of various articulators, including tongue, mandible, and lips [35], [36]. The same basic mechanisms also play a role during vocal production in non-human primates, as illustrated by studies with Diana monkeys and other non-human primates [37]–[40]. Our results thus add to the growing literature that non-human primates use processes similar to the ones that are fundamental during speech production to communicate about events in their environment in a meaningful way.…”

Mechanisms of song production in the Australian magpie

“…Tension in the lateral portion of the vocal fold causes it to shorten and thicken, moving the margin of the vocal folds medially (Whitehead et al 1984; Blomgren and Chen 1998; Seikel et al 2005). Pulse phonation has also been recorded from other mammals including felids and primates (e.g., Riede and Zuberbühler 2003). …”