Piette, T. | Search bioRxiv

bioRxiv2024

Animal acoustic communication maintains a universal optimum rhythm

Most animals interact with conspecifics through acoustic signals that are modulated in frequency and rhythm. While small animals vocalize at higher pitch than large ones due to the smaller size of their vocal apparatus, the rules governing vocalization rhythms throughout the animal kingdom remain unknown. Vocal rhythms serve as a natural information parser, and one possibility is that they are constrained by the neural rhythms of transmitter and receiver, known to be relatively conserved across species and independent of their size. In this study, we quantified acoustic rhythms across taxa and investigated their evolutionary history with regard to phylogeny and selective pressure. In 98 species from six classes, we tested the main factors likely to influence their communication rhythms: morphology, physiology, social complexity, mastication and detectability. Phylogenetic modeling did not confirm the influence of these species-specific factors, but rather point to a scenario where acoustic communication rhythms have been maintained around an optimum at around 3Hz in the biological (neuronal) delta range (1-4Hz) well before the mammals split. These results suggest that the rhythm of acoustic communication signals, unlike their pitch, has a universal neural determinant that has been conserved throughout evolution, allowing for intra- and cross-species signaling.

animal behavior and cognition↗

bioRxiv2023

Dogs' sensory-motor tuning shapes dog-human vocal interactions

Within species, vocal and auditory systems co-evolve to converge on a critical temporal acoustic structure that can be best produced and perceived. While dogs cannot produce articulated sounds, they respond to speech, raising the question as to whether this heterospecific receptive ability is shaped by exposure to speech or bounded by their own sensorimotor capacity. Acoustic analyses of vocalisations show that dogs main production rhythm is slower than the dominant (syllabic) speech rate, and that human dog-directed speech falls halfway in between. Comparative exploration of neural (electroencephalography) and behavioural responses to speech reveals that comprehension in dogs relies on a slower speech rhythm tracking (delta) than humans (theta), even though dogs are equally sensitive to human speech content and prosody. Thus, the dog audio-motor tuning differs from humans, who vocally adjust their speech rate to this shared temporal channel.

neuroscience↗