Editorial: vocal communication in corvids.

Vocal communication is broadly distributed in a wide range of nonhuman animal species and is hypothesized to play an important role in mate attraction, territory defence, predator avoidance and parental care. Understanding the ecological and social drivers of vocal communication is key to enhancing our understanding of the evolution of social structures, mating systems and group dynamics. We reviewed 130 studies investigating vocal communication in the family of corvids. As oscine passerines, living in complex and flexible social systems and a wide range of ecological systems (e.g. different habitats, trophic niches), corvids present a key model group in advancing our understanding of evolutionary drivers of vocal communication. Here, we outline empirical evidence for vocal learning, ecological adaptation (e.g. calls encoding information about predator type) and social adaptation (e.g. vocalizations for group cohesion and coordination) in corvid vocalizations and behavioural responses of receivers to calls. Only 35 out of 128 (27%) of corvid species have been studied with regards to their vocal communication. While some species, like American crows, common ravens and Eurasian magpies, are well studied, and supporting evidence for vocal learning and ecological as well as social adaptations is available, most corvid species remain poorly studied. We hope our review will inspire future work on previously underinvestigated corvid species, as well as replications of previous research with standardized observational and experimental paradigms, to allow for direct comparison between different corvid species. More broadly, further research systematically investigating social and ecological factors driving variation in vocal communication systems is necessary to further advance our general understanding of animal vocal communication. • Vocal communication is broadly distributed in a range of nonhuman animal species. • We review 130 studies investigating vocal communication in the family of corvids. • Evidence for vocal learning is described in nine corvid species. • Information about the environment (predators, food) is provided in calls. • Social aspects of calls (e.g. group cohesion) are shown in 31 species.

Songbirds are capable of vocal learning and communication and are ideally suited to the study of neural mechanisms of complex sensory and motor processing. Vocal communication in a noisy bird colony and vocal learning of a specific song template both require the ability to monitor auditory feedback to distinguish self-generated vocalizations from external sounds and to identify mismatches between the developing song and a memorized template acquired from a tutor. However, neurons that respond to auditory feedback from vocal output have not been found in song-control areas despite intensive searching. Here we investigate feedback processing outside the traditional song system, in single auditory forebrain neurons of juvenile zebra finches that were in a late developmental stage of song learning. Overall, we found similarity of spike responses during singing and during playback of the bird's own song, with song responses commonly leading by a few milliseconds. However, brief time-locked acoustic perturbations of auditory feedback revealed complex sensitivity that could not be predicted from passive playback responses. Some neurons that responded to playback perturbations did not respond to song perturbations, which is reminiscent of sensory-motor mirror neurons. By contrast, some neurons were highly feedback sensitive in that they responded vigorously to song perturbations, but not to unperturbed songs or perturbed playback. These findings suggest that a computational function of forebrain auditory areas may be to detect errors between actual feedback and mirrored feedback deriving from an internal model of the bird's own song or that of its tutor. Such feedback-sensitive spikes could constitute the key signals that trigger adaptive motor responses to song disruptions or reinforce exploratory motor gestures for vocal learning.

Purpose We examined associations between vocal communication with canonical syllables and expressive language and then examined 2 potential alternative explanations for such associations. Method Specifically, we tested whether the associations remained when excluding canonical syllables in identifiable words and controlling for the number of communication acts. Participants included 68 preverbal or low verbal children with autism spectrum disorder (M age = 35.26 months). Results Vocal communication with canonical syllables and expressive language were concurrently and longitudinally associated with moderate to strong (R 2s = .13-.70) and significant (ps < .001) effect sizes. Even when excluding spoken words from the vocal predictor and controlling for the number of communication acts, vocal communication with canonical syllables predicted expressive language. Conclusions The findings provide increased support for measuring vocal communication with canonical syllables and for examining a causal relation between vocal communication with canonical syllables and expressive language in children with ASD who are preverbal or low verbal. In future studies, it may be unnecessary to eliminate identifiable words when measuring vocal communication in this population. Following replication, vocal communication with canonical syllables may be considered when making intervention- planning decisions.

Songbirds are renowned for their complex vocal communication abilities; among them, zebra finches (Taeniopygia guttata) are a key species for studying vocal learning and communication. Zebra finches use various calls with different meanings, including the distance call, which is used for long-distance contact. Whether these calls are static with fixed meanings or flexible remains an open question. In this study we aimed to answer this question by designing a novel behavioral paradigm, in which we trained food-restricted zebra finches to use distance calls for food request. Nine out of ten birds learned this association and used their distance calls to obtain food when they were hungry. We then introduced a visually-separated audience and compared the distance calls used for food requests with those used for communication between birds. Our analyses revealed significant acoustic differences in power, pitch, and other spectral characteristics between the distance calls uttered in these two contexts, with calls directed at conspecifics exhibiting higher amplitude. Our findings suggest that zebra finches can use their distance call for different goals and also acoustically modulate it based on the context. Therefore, it demonstrates a level of vocal control thought to be exclusive to songs. This study enhances our understanding of vocal flexibility and its role in vocal communication.

In searching for the roots of human language, comparative researchers investigate whether precursors to language are already present in our closest relatives, the non-human primates. As the majority of studies into primates’ communication use a unimodal approach with focus on one signal type only, researchers investigate very different aspects depending on whether they are interested in vocal, gestural, or facial communication. Here, we focus on two signal types and discuss how meaning is created in the gestural (visual, tactile/auditory) as compared to the vocal modality in non-human primates, to highlight the different research foci across these modalities. First, we briefly describe the defining features of meaning in human language and introduce some debates concerning meaning in non-human communication. Second, with focus on these features, we summarize the current evidence for meaningful communication in gestural as compared to vocal communication and demonstrate that meaning is operationalized very differently by researchers in these two fields. As a result, it is currently not possible to generalize findings across these modalities. Rather than arguing for or against the occurrence of semantic communication in non-human primates, we aim at pointing to gaps of knowledge in studying meaning in our closest relatives, and these gaps might be closed.

Animal Models of Speech and Vocal Communication Deficits Associated With Psychiatric Disorders

In some animal species, individuals develop strong and enduring social bonds, which promote cooperation and usually offer significant fitness advantages. In these highly social species, individuals need to be able to coordinate and negotiate their complex social relationships but how do they do so? Does high sociality promote the evolution of specific communicative signals to manage these relationships? These issues becomes even more problematic for species with fluid social structures, where cohesion between group members varies constantly. Chimpanzees are an ideal model species to study these questions, as they present a high degree of fission-fusion dynamics. In this species, males are more gregarious than females and form highly strong and stable bonds with unrelated individuals of the same sex. These bonds, which can manifest in various contexts, such as grooming and intragroup conflicts, play a crucial role in establishing dominance relations between males and have a significant impact on their reproductive success. However, how do males choose their social partners and how do they maintain their relationships with their preferred partners? By empirically investigating the vocal communication and social cohesion of male chimpanzees in various contexts, this thesis aimed to elucidate how males use vocalisations to manage their social relationships. I first explored specific contexts where social bonds are under strain, i.e., when the social composition of the subgroup is likely to change. Hence, I studied the vocal production of short and long distance calls (i.e., ‘pant hoots’ and ‘rough grunts’) by male chimpanzees upon their arrival at food trees, an socially challenging event, as it is particularly prone to outbreaks of aggression but also offers opportunities for cooperation. I showed that vocal communication in this context appeared to have a dual function to mediate both cooperative and competitive interactions, with males producing ‘pant hoots’ to cooperatively inform absent social partners about the presence of food whereas ‘rough grunts’ seemed to be produced as part of competitive interactions, to avoid aggression. Secondly, I investigated the vocal production of ‘rest hoos’, a context-specific vocalisation given while resting, another context during which the subgroup composition is threatened due to forthcoming travel. My findings provided evidence that ‘rest hoos’ were produced intentionally to prolong resting bouts with desired partners, and that their function would thus be to help manage social cohesion. Furthermore, I discovered that low-ranking males who did not groom often produced ‘rest hoos’ more frequently than other males, hence suggesting that vocal communication could serve as an alternative cohesion strategy to tactile-based bonding. Finally, I described the patterns of dyadic short-term associations between males (i.e., periods of time during which males stay in each other’s visual range) and showed that these associations were mostly determined by dominance relations, as high-ranking males were more effective in prolonging associations when producing a ‘hoo’ and were also more likely to terminate the associations. I also specifically investigated whether males used vocal signals (i.e., production of ‘hoo’ vocalisations) or tactile behaviour (i.e., grooming) to manage these associations and found that 'hoo' vocalisations but not grooming had a significant impact on association patterns, suggesting not only that males produced these calls strategically to ensure social cohesion but also that vocalisations may be a more reliable predictor of short-term affiliations than grooming. Overall, these findings provide evidence that vocalisations have various social functions, including mediating social cohesion and managing both cooperative and competitive interactions, and are therefore playing an essential role in chimpanzee fission-fusion societies. The results presented in this thesis will help better understand chimpanzee vocal communication and socio-cognitive abilities as well as further our comprehension of how complex social systems shaped the evolution of animal communication.

Using frequency ratios to study vocal communication

Family-living and pair-bonded primates, such as gibbons, night monkeys, titi monkeys, marmosets, and tamarins, have some different social and ecological challenges than other primates and thus display some differences in vocal communication. Shared parental care, territory defense, pair-bond maintenance, and frequent exchange of roles throughout the day are common in family-living and pair-bonded primates. These species are usually sexually monomorphic, and they show relatively few sex differences in vocal output. Vocal communication is important in forming and maintaining pair bonds and in defending the pairs or family territory. In addition, these species appear to use vocal communication to a greater degree during social learning and putative teaching behavior, and adults appear to guide vocal development in young through reinforcement of vocal behavior. Adults of these species show great flexibility and plasticity in both vocal structure and usage in response to both social and environmental variation. They also adjust vocal output according to habitat acoustics to maximize audibility and minimize risk of predation. This chapter examines each of these areas of vocal communication to illustrate how family-living and pair-bonding primates use vocal communication.

Marmoset monkeys exhibit complex vocal communication, challenging the view that nonhuman primates' vocal communication is entirely innate, and show similar features of human speech, such as vocal labeling of others and turn-taking.Studying their vocal communication offers a unique opportunity to link it with brain activity-especially given the difficulty of accessing the human brain in speech and language research.Since Marmosets communicate primarily through vocalizations, applying standard LLM approaches is not straightforward.We introduce Generative Marmoset Spoken Language Modeling (GMSLM), an optimized spoken language model pipeline for Marmoset vocal communication.We designed a novel zero-shot evaluation metrics using unsupervised in-the-wild data, alongside weakly labeled conversational data, to assess GMSLM and demonstrate its advantage over a basic human-speech-based baseline.GMSLM generated vocalizations closely matched real resynthesized samples acoustically and performed well on downstream tasks.Despite being fully unsupervised, GMSLM effectively distinguish real from artificial conversations and may support further investigations of the neural basis of vocal communication and provides a practical framework linking vocalization and brain activity.We believe GMSLM stands to benefit future work in neuroscience, bioacoustics, and evolutionary biology.Samples are provided under: this link.

To shed light on the evolution of human language, many studies have been made on the vocal communication of nonhuman primates. These studies have revealed that some rudimentary properties of human language can be seen in nonhuman primate vocal communication. In particular, much knowledge about the natural vocal communication of primates has accumulated since the method of playback experiments was established. For example, referential signaling (Zuberbuhler et al. 1999), categorical perception of vocalization (Masataka 1983), acoustic “rules” regulating vocal exchange (Sugiura 1993), and flexibility of vocal production (Sugiura 1998) have been found in some primate species in natural habitats. However, most of these studies have been conducted on the anthropoid primates. There have been relatively few studies on vocal communication in prosimians, including the lemurs of Madagascar, which are indigenous to the island and have evolved separately. Because of their uniqueness, the lemurs are important species as subjects for comparative studies of primate vocal communication.

This paper explores strategies for fostering efficient vocal communication and collaboration between human workers and collaborative robots (cobots) in assembly processes. Vocal communication enables the division of attention of the worker, as it frees their visual attention and the worker’s hands, dedicated to the task at hand. Speech generation and speech recognition are pre-requisites for effective vocal communication. This study focuses on cobot assistive tasks, where the human is in charge of the work and performs the main tasks while the cobot assists the worker in various peripheral jobs, such as bringing tools, parts, or materials, and returning them or disposing of them, or screwing or packaging the products. A nuanced understanding is necessary for optimizing human–robot interactions and enhancing overall productivity and safety. Through a comprehensive review of the relevant literature and an illustrative example with worked scenarios, this manuscript identifies key factors influencing successful vocal communication and proposes practical strategies for implementation.

To obtain further evidence that action observation can serve as a proxy for action execution and planning in posterior parietal cortex, we scanned participants while they were (1) observing two classes of action: vocal communication and oral manipulation, which share the same effector but differ in nature, and (2) rehearsing and listening to nonsense sentences to localize area Spt, thought to be involved in audio-motor transformation during speech. Using this localizer, we found that Spt is specifically activated by vocal communication, indicating that Spt is not only involved in planning speech but also in observing vocal communication actions. In addition, we observed that Spt is distinct from the parietal region most specialized for observing vocal communication, revealed by an interaction contrast and located in PFm. The latter region, unlike Spt, processes the visual and auditory signals related to other's vocal communication independently. Our findings are consistent with the view that several small regions in the temporoparietal cortex near the ventral part of the supramarginal/angular gyrus border are involved in the planning of vocal communication actions and are also concerned with observation of these actions, though involvements in those two aspects are unequal.

In many species, vocal communication is essential for coordinating social behaviors including courtship, mating, parenting, rivalry, and alarm signaling. Effective communication requires accurate production, detection, and classification of signals, as well as selection of socially appropriate responses. Understanding how signals are generated and how acoustic signals are perceived is key to understanding the neurobiology of social behaviors. Here we review our long-standing research program focused on Xenopus, a frog genus which has provided valuable insights into the mechanisms and evolution of vertebrate social behaviors. In Xenopus laevis, vocal signals differ between the sexes, through development, and across the genus, reflecting evolutionary divergence in sensory and motor circuits that can be interrogated mechanistically. Using two ex vivo preparations, the isolated brain and vocal organ, we have identified essential components of the vocal production system: the sexually differentiated larynx at the periphery, and the hindbrain vocal central pattern generator (CPG) centrally, that produce sex- and species-characteristic sound pulse frequencies and temporal patterns, respectively. Within the hindbrain, we have described how intrinsic membrane properties of neurons in the vocal CPG generate species-specific vocal patterns, how vocal nuclei are connected to generate vocal patterns, as well as the roles of neurotransmitters and neuromodulators in activating the circuit. For sensorimotor integration, we identified a key forebrain node that links auditory and vocal production circuits to match socially appropriate vocal responses to acoustic features of male and female calls. The availability of a well supported phylogeny as well as reference genomes from several species now support analysis of the genetic architecture and the evolutionary divergence of neural circuits for vocal communication. Xenopus thus provides a vertebrate model in which to study vocal communication at many levels, from physiology, to behavior, and from development to evolution. As one of the most comprehensively studied phylogenetic groups within vertebrate vocal communication systems, Xenopus provides insights that can inform social communication across phyla.

Vocal communication is an important method squirrels (Sciuridae) use to transfer information from one individual to others. While behaviors associated with vocal communication have been explored in individual species or single call‐types in specific groups of squirrels, no comprehensive review of these behaviors exists for Sciuridae. Herein, I review the current literature to describe behaviors associated with vocal communication in three groups of squirrels: ground squirrels, tree squirrels, and flying squirrels. I discuss the behavioral functions of squirrel vocalizations. A wide variety of behaviors are associated with particular call‐types produced by squirrels, including alarm, agonistic, discomfort, affiliative, mating, and neonatal calls. There are large knowledge gaps in cataloging the vocal repertoires and associated behaviors of many species of squirrels, including commonly studied species such as marmots and ground squirrels, as alarm calls are typically focused on and other call‐types are understudied or ignored. Since vocal communication is important to the development, reproduction, and survival of squirrels, further understanding the biological and ecological drivers behind vocal repertoires is critical to evaluating the ethology of this family as a whole.