Vocal Patterns Research Articles

Classification of Dysphonic Voices in Parkinson's Disease with Semi-Supervised Competitive Learning Algorithm.

This article proposes a novel semi-supervised competitive learning (SSCL) algorithm for vocal pattern classifications in Parkinson’s disease (PD). The acoustic parameters of voice records were grouped into the families of jitter, shimmer, harmonic-to-noise, frequency, and nonlinear measures, respectively. The linear correlations were computed within each acoustic parameter family. According to the correlation matrix results, the jitter, shimmer, and harmonic-to-noise parameters presented as highly correlated in terms of Pearson’s correlation coefficients. Then, the principal component analysis (PCA) technique was implemented to eliminate the redundant dimensions of the acoustic parameters for each family. The Mann–Whitney–Wilcoxon hypothesis test was used to evaluate the significant difference of the PCA-projected features between the healthy subjects and PD patients. Eight dominant PCA-projected features were selected based on the eigenvalue threshold criterion and the statistical significance level (p < 0.05) of the hypothesis test. The SSCL algorithm proposed in this paper included the procedures of the competitive prototype seed selection, K-means optimization, and the nearest neighbor classifications. The pattern classification experimental results showed that the proposed SSCL method can provide the excellent diagnostic performances in terms of accuracy (0.838), recall (0.825), specificity (0.85), precision (0.846), F-score (0.835), Matthews correlation coefficient (0.675), area under the receiver operating characteristic curve (0.939), and Kappa coefficient (0.675), which were consistently better than those results of conventional KNN or SVM classifiers.

Breeding status shapes territoriality and vocalization patterns in spotted owls

Vocal territory defense can vary within a species due to many factors such as sex and breeding status, influencing territory size and thus population density across a landscape. Therefore, understanding what influences variation in territorial vocalizations can help to illuminate trade‐offs between territoriality and other life history demands, which benefits our general understanding of animal ecology as well as helps to inform emerging passive acoustic monitoring approaches. Here, we investigated how sex and breeding status affected territoriality and vocal behavior in the California spotted owl Strix occidentalis occidentalis in the Sierra Nevada, California, USA, using high‐resolution acoustic/GPS tags. We discovered that territorial vocal behavior was related to breeding status and to a lesser extent sex. Breeding owls with fledged young had a less diverse vocal repertoire, produced fewer and quieter territorial calls, and typically called only when close to their nest. Males were also more likely to engage in territorial calling than females. Breeding spotted owls also maintained significantly smaller territories – but utilized larger home ranges – than non‐breeding individuals. Our results suggest that breeding spotted owls may reduce their investment in territorial behaviors to mitigate the demands and risks associated with rearing young. Further, our results have important implications for the passive acoustic monitoring of spotted owls and, more broadly, highlight the utility of using multiple call types to detect species of interest.

Vocal Behavior in Spotted Seals (Phoca largha) and Implications for Passive Acoustic Monitoring

Passive acoustic methods enable remote monitoring of marine species and habitats. These methods can be applied to investigate distribution and abundance of populations, to evaluate behavioral and physiological states of individuals, and to inform management efforts for animals that live in hard-to-reach places. Spotted seals (Phoca largha) inhabit high-latitude, light-limited sub-Arctic and Arctic waters and move seasonally with unstable sea ice. They are high trophic level predators vulnerable to changing conditions associated with environmental warming. At present, an incomplete characterization of the spotted seal vocal repertoire limits our ability to monitor this species acoustically. Captive studies can inform passive acoustic efforts by describing fundamental features of species-typical vocalizations emitted by known individuals. These features include acoustic parameters as well as developmental, seasonal, and sex-specific patterns in vocal behavior. Here, we studied several male spotted seals in captivity from age 6 months through adulthood (10 years). Vocal behavior was scored daily and opportunistically recorded. The production of underwater calls emerged during sexual maturation, at age 4. To evaluate vocal repertoire and fine-scale temporal patterns of sound production in adult seals, an underwater acoustic recorder was continuously deployed with two seals at age 7 years. The spotted seals produced at least eight distinctive underwater call types with dominant energy below 1 kHz. The amplitude of the most common vocalization was ∼140 dB re 1 μPa (sound pressure level at 1 m). There was a marked peak in vocal activity in springtime, prior to onset of the annual molt. This period coincided with increased aggressive behavior, presence of a notable musky odor, and urogenital swelling indicative of heightened reproductive status. These results from developing male spotted seals reared in human care confirm the production of recognizable, stereotypic underwater calls associated with the breeding season. Description of vocal behavior improves knowledge of this species’ biology, and informs the potential use of autonomous acoustic recorders to track the presence and movements of free-ranging spotted seals in remote habitats.

Early Detection of Male-Predominant Phenotypes in the Pattern of Ultrasonic Vocalizations Emitted by Autism Spectrum Disorder Model (Crmp4-Knockout) Mice.

Male predominance is a known feature of autism spectrum disorder (ASD). Although ASD mouse models can be useful for elucidating mechanisms underlying abnormal behaviors relevant to human ASD, suitable models to analyze sex differences in ASD pathogenesis remain insufficient. Herein, we used collapsin response mediator protein 4 (Crmp4)-knockout (KO) mice exhibiting ASD-like phenotypes in a male-predominant manner and analyzed ultrasonic vocalizations (USVs) to detect potential differences between genotypes and sexes during the early postnatal period. We recorded isolation-induced USVs emitted from wild-type (WT) and Crmp4-KO littermates and compared the total number of USVs between genotypes and sexes. We classified USVs into 10 types based on internal pitch changes, lengths, and shapes and compared the number of USVs in each type by genotypes and sex. Male Crmp4-KO mice exhibited a reduction in the total number of USVs. Crmp4-KO decreased the number of USVs in 7 out of 10 USV types, and male KO mice exhibited a greater reduction than females in 3 of the 7 types. This study offers a suitable ASD animal model and tool for assessing sex-based communication deficits during the early postnatal period, both of which would be valuable for elucidating the underlying mechanism.

Microgeographical variation in birdsong: Savannah sparrows exhibit microdialects in an island population

Social communication often involves vocal learning, whereby young animals learn their vocalizations early in life by imitating the sounds of adults. In animals that learn their vocalizations, it is common to find patterns of geographical variation known as ‘vocal dialects’, acoustic features shared within a cluster of animals that differ from the vocalizations of animals in nearby clusters. Dialects may form when animals learn their vocalizations early in life and then disperse short distances, or when they modify their vocalizations to match local vocal patterns after dispersal. Dialects are typically studied at a regional or continental scale, but they may also persist at smaller scales in so-called ‘microgeographical song dialects’ or ‘microdialects’. Microdialects have received little research attention. In this study, we investigate microdialects and dispersal distance in song-learning Savannah sparrows, Passerculus sandwichensis, through a 4-year study of birds living on three islands in the Bay of Fundy, Canada. Our analyses yield evidence of microgeographical variation: birds showed higher acoustic similarity to their neighbours than to faraway individuals in the same population. When we classified songs on the basis of their highly variable middle sections, we found that particular song types formed spatial clusters of similar-sounding individuals. Therefore, acoustic variation in Savannah sparrow song appears to show dialects across small geographical distances. In an analysis of dispersal from natal sites to breeding sites, we found a median distance of 189 m, consistent with previous findings. Our results suggest that limited dispersal distances, combined with the social processes of vocal learning (overproduction and selective attrition), likely contribute to the presence of microdialects.

Ultrasonic vocalizations – Novel seizure-related manifestation in rats

ObjectiveSeizures of frontal or temporal lobe origin can associate with vocalizations in humans. Our objective was to assess whether rats emit specific seizure-related patterns of ultrasonic vocalizations (USVs) during seizures and epileptiform activity. MethodsAdult male Sprague-Dawley rats were treated with a single administration of pentylenetetrazol (PTZ, 50 mg/kg, i.p.) and monitored with simultaneous USV and video-electroencephalogram recordings for up to 15 min. USVs were detected using a deep learning algorithm (DeepSqueak-Screener) and manually annotated into the 15 previously described subcategories. The number, frequency, duration, sonographic structure, and temporal relationship of the USVs to seizures and epileptiform activity were assessed. ResultsA total of 2147 USVs were recorded in 12 rats that expressed a total of 22 PTZ-induced seizures. Of the USVs, 77% were in the 50-kHz range (i.e., appetitive state) and 23% in the 22-kHz ( i.e., aversive state) range. More than a third (37%) of the USVs could be classified into 1 of the 15 call subcategories; the remaining 63% belonged to a novel “multiform” USV category with a complex sonographic structure. Of the 2147 USVs, 23% occurred during the PTZ-induced seizures and 77% during other types of PTZ-induced epileptiform activity. Almost all (19/22) of seizures were associated with USVs. In each rat, the first seizure was always associated with a USV. The shorter the latency to the first USV, the shorter the latency to the onset of the first electrographic seizure (r = 0.995, p < 0.001). The greater the number of USVs, the greater the number of seizures (r = 0.916, p < 0.001) and the longer the total seizure duration in a given rat (r = 0.750, p < 0.05). SignificanceLike in humans, vocalizations are a seizure-related behavioral feature in rats and recording USVs provides a novel noninvasive tool for detecting experimental seizures. Further studies are needed to explore USV occurrence during spontaneous seizures and their potential for screening novel anti-seizure drugs.

Mapping the vocal circuitry of Alston's singing mouse with pseudorabies virus.

Vocalizations are often elaborate, rhythmically structured behaviors. Vocal motor patterns require close coordination of neural circuits governing the muscles of the larynx, jaw, and respiratory system. In the elaborate vocalization of Alston's singing mouse (Scotinomys teguina) each note of its rapid, frequency-modulated trill is accompanied by equally rapid modulation of breath and gape. To elucidate the neural circuitry underlying this behavior, we introduced the polysynaptic retrograde neuronal tracer pseudorabies virus (PRV) into the cricothyroid and digastricus muscles, which control frequency modulation and jaw opening, respectively.Each virus singly labels ipsilateral motoneurons (nucleus ambiguus for cricothyroid, and motor trigeminal nucleus for digastricus). We find that the two isogenic viruses heavily and bilaterally colabel neurons in the gigantocellular reticular formation, a putative central pattern generator. The viruses also show strong colabeling in compartments of the midbrain including the ventrolateral periaqueductal gray and the parabrachial nucleus, two structures strongly implicated in vocalizations. In the forebrain, regions important to social cognition and energy balance both exhibit extensive colabeling. This includes the paraventricular and arcuate nuclei of the hypothalamus, the lateral hypothalamus, preoptic area, extended amygdala, central amygdala, and the bed nucleus of the stria terminalis. Finally, we find doubly labeled neurons in M1 motor cortex previously described as laryngeal, as well as in the prelimbic cortex, which indicate these cortical regions play a role in vocal production. The progress of both viruses is broadly consistent with vertebrate-general patterns of vocal circuitry, as well as with circuit models derived from primate literature.

Effects of Age and Parkinson's Disease on the Relationship between Vocal Fold Abductory Kinematics and Relative Fundamental Frequency

This study reports on two experiments to examine vocal fold abduction and its relationship with relative fundamental frequency (RFF), considering two attributes that have been shown to elicit group differences in RFF: age (Experiment 1) and Parkinson's disease (PD; Experiment 2). For both experiments, simultaneous acoustic and nasendoscopic recordings were collected as participants produced the utterance, /ifi/. RFF values were computed from the acoustic signal, whereas abduction duration and glottic angle at voicing offset were identified from the laryngoscopic images. In Experiment 1, 50 speakers with typical voices (18-83 years) were analyzed to examine (1A) the effects of speaker age on individual outcome measures (RFF, abduction duration, glottic angle) via Pearson's correlation coefficients, and (1B) the effects of abductory measures and age on RFF via an analysis of covariance. In Experiment 2, 20 speakers with PD and 20 matched controls were analyzed to examine (2A) the effects of group (with/without PD) on outcome measures via an analysis of variance, and (2B) the relationship of RFF with abduction duration, glottic angle, and age when considering group via an analysis of covariance. Age demonstrated a significant, negative relationship with glottic angle (1A) but was not a significant factor when examining the relationship of vocal fold abduction and RFF (1B). Speaker group (with/without PD) demonstrated a significant effect on measures of RFF and abduction duration (2A) but was not a significant factor when examining the relationship of vocal fold abduction and RFF (2B). RFF is sensitive to changes in vocal fold abductory patterns during devoicing, irrespective of speaker age or PD status.

Comparison of one-dimensional and three-dimensional glottal flow models in left-right asymmetric vocal fold conditions

While the glottal flow is often simplified as one-dimensional (1D) in computational models of phonation to reduce computational costs, the 1D flow model has not been validated in left-right asymmetric vocal fold conditions, as often occur in both normal and pathological voice production. It is unclear to what extent the 1D model approximates the effect of three-dimensional (3D) flow phenomena and fluid-structure interaction. In this study, we performed 1D and 3D flow simulations coupled with the two-mass vocal fold model and compared vocal fold vibration patterns at different degrees of left-right stiffness asymmetry. The flow and acoustic fields in 3D were predicted by solving the compressible Navier-Stokes equations using the volume penalization method and considering the moving vocal fold wall as an immersed boundary. The results showed that vocal fold vibration amplitudes and left-right phase differences in the 3D flow were predicted by the 1D flow model under conditions of small left-right asymmetry, while vocal fold vibration amplitudes were underestimated at conditions of large left-right asymmetry. This indicates that 1D flow models may be sufficient in modeling phonation under left-right asymmetric conditions, although the performance can be further improved by more accurately predicting air pressure on vocal fold surface.

Vocal Fry Patterns While Reading

The use of vocal fry is common in running speech and has potential psychosocial and vocal health consequences. Determining the different patterns of vocal fry is relevant to differentiating phonatory function, understanding cultural and linguistic use of vocal fry, and clinical diagnostics and intervention. The purpose of this project was to study and categorize patterns of vocal fry in running speech. Analyses were performed on recordings of the Rainbow Passage read out loud by five healthy females 18-21 years old. Praat was used to create audio files with text grids. The audio recordings were examined visually (the audio signal and its spectrogram) and perceptually in order to determine different patterns of vocal fry seen in the audio signal. Criteria for detecting vocal fry were (1) the presence of an acoustic transient (a relatively large and fast dip in acoustic pressure, presumably near glottal closure) with a relatively long cycle period compared to normal phonation periods, or (2) a frequency at or lower than approximately an octave below the nearby normal speaking fundamental frequency. There were 174 total vocal fry samples obtained from the recordings. Six vocal fry patterns were observed. The patterns were: single pulse fry (FRY1), double pulse fry (FRY2), multiple pulse fry (FRY3), period doubling fry (FRY4), inaudible fry (FRY5), and indeterminate vocal fry (FRY6). Single pulse fry was divided into a single (one) pulse fry cycle (FRY1a), a series of even single pulse fry cycles (FRY1b), and a series of uneven single pulse fry cycles (FRY1c). Double pulse fry was divided into a primary then another primary pulse fry cycle (FRY2a), a secondary then a primary pulse fry cycle (FRY2b), and a primary then a secondary pulse fry cycle (FRY2c). Multiple pulse fry, where a higher frequency was modulated by a lower frequency, was divided into the higher frequency being near the speaking fundamental frequency (FRY3a) and the higher frequency being inconsistent or well below the expected speaking fundamental frequency (FRY3b). The category single pulse fry had the most samples, with 76% of the total occurrences, followed by period doubling 13%, and the rest 11%. Relative to where the fry patterns occurred within syllables, 36% occurred at the onset of the syllable, 26% early in the syllable, 25% later in the syllable, and 13% at the end of the syllable. These tallies did not include the sixth category, indeterminate vocal fry (FRY6), which was not included in the study proper but recognized as indicating complicated patterns that did not fall within the first five categories. Vocal fry is a complex, multifaceted phenomenon. The results of this study suggest that there are identifiable patterns of vocal fry. These patterns need to be differentiated especially regarding the glottal adductory nature and phonatory function of each pattern, glottal closure appearing to be the primary physiological causative factor of the salient negative pressure dips (the adduction behavior will be reported in a study in progress). Further research is necessary to determine other potential categories of vocal fry, determine if there are individual idiosyncratic patterns of vocal fry, determine possible differences in vocal fry produced by individuals of different ages and gender expression and other factors, and research the physiologic, acoustic, aerodynamic, and perceptual reality of each pattern.

Behavioural context shapes vocal sequences in two anuran species with different repertoire sizes

Acoustic signals in animals serve to convey context-dependent information to receivers. Birds and mammals combine diverse sounds into complex sequences to communicate, but the role of temporal sequencing of signals remains understudied in other taxa. Anuran vocalizations are a prominent feature of their life history, and function in defence of territories and to attract mates. However, there are few data on whether anurans pattern their calls into sequences, and whether temporal sequences convey information about context. Here, we investigated the context-dependent vocal repertoire and the use of vocal sequences by two anuran species belonging to different lineages, comparing frogs vocalizing alone and in the presence of a territorial rival. Using a robust analytical framework, we present evidence that both species modify their vocal sequence structure according to context. Specifically, one species (with a smaller repertoire, from a more basal lineage) appends notes to generate more complex sequences, whereas the other (more recently diverged and with a larger repertoire) shifts to different note types, resulting in different sequences for different contexts. Thus, despite differences in repertoire size, both frog species are capable of adjusting the temporal sequence of vocalizations to communicate in different contexts. Vocal sequences and context-dependent ‘syntax’ may be more common in anurans than previously thought, and our methodology presents a paradigm to study the evolution and function of these complex vocal patterns.

Monitoring vocal activity and temporal patterns in attendance of White-chinned Petrels using bioacoustics

ABSTRACT Monitoring of population sizes and trends using conventional surveys is challenging for nocturnal, burrow-nesting seabirds. The White-chinned Petrel is the most commonly killed species in Southern Ocean fisheries and its breeding success at many sites is reduced because of predation by invasive cats and rodents. As adaptive management of such threats requires cost-effective and reproducible protocols for monitoring populations, we examined the potential of automated bioacoustic techniques for measuring colony attendance patterns (relative number of birds visiting at a given time) using data from acoustic recorders deployed over a breeding season at Bird Island, South Georgia. Generic recognition software was of limited utility, but a suite of acoustic indices in a random forest model reliably predicted the occurrence of vocalisations. Vocal activity showed clear temporal patterns, despite high day-to-day variability, and was lowest during the pre-laying period, in the early evening, and on moonlit nights. To facilitate estimation of population density using acoustic recorders, we determined the mean vocalisation rate of individuals (2.3 min−1), mean call length (~15.3 sec), and detection distance (~15 m based on signal to noise ratios of playbacks). Our results indicate that acoustic indices are a useful measure of colony attendance. If these indices can be linked to density, acoustic monitoring would provide a powerful and cost-effective census method for White-chinned Petrels and other nocturnal species.

ANALYSIS ON DIFFERENT METHODS FOR SIGN LANGUAGE IDENTIFICATION

Sign Language (SL) is the most organized and structured type of hand/arm gesture in the communicative hand/arm gesture taxonomies. The ability of machines to comprehend human actions and meanings has numerous uses. SL identification is one area of focus. SL is employed by the deaf and hard-of-hearing communities to communicate. Hearing-impaired persons communicate via visual indicators instead of vocal communication and sound patterns. SL also uses facial expressions and body postures as a medium of communication. Pattern matching, computer vision, natural language processing are the key factors in SL identification. This study reviews state-of-the-art methodologies employed in current SL identification research, comparing the various algorithms at each stage. Discuss the challenges and limitations of gesture identification research in general, as well as SL identification in particular. Overall, this paper gives a thorough introduction to the topic of automated SL identification, paving the way for future research.

Functional patterns of neural activation during vocal emotion recognition in youth with and without refractory epilepsy

Epilepsy has been associated with deficits in the social cognitive ability to decode others’ nonverbal cues to infer their emotional intent (emotion recognition). Studies have begun to identify potential neural correlates of these deficits, but have focused primarily on one type of nonverbal cue (facial expressions) to the detriment of other crucial social signals that inform the tenor of social interactions (e.g., tone of voice). Less is known about how individuals with epilepsy process these forms of social stimuli, with a particular gap in knowledge about representation of vocal cues in the developing brain. The current study compared vocal emotion recognition skills and functional patterns of neural activation to emotional voices in youth with and without refractory focal epilepsy. We made novel use of inter-subject pattern analysis to determine brain areas in which activation to emotional voices was predictive of epilepsy status. Results indicated that youth with epilepsy were comparatively less able to infer emotional intent in vocal expressions than their typically developing peers. Activation to vocal emotional expressions in regions of the mentalizing and/or default mode network (e.g., right temporo-parietal junction, right hippocampus, right medial prefrontal cortex, among others) differentiated youth with and without epilepsy. These results are consistent with emerging evidence that pediatric epilepsy is associated with altered function in neural networks subserving social cognitive abilities. Our results contribute to ongoing efforts to understand the neural markers of social cognitive deficits in pediatric epilepsy, in order to better tailor and funnel interventions to this group of youth at risk for poor social outcomes.

How versatility performance influences perception of charismatic speech

Abstract The concept of vocal charisma has changed in the past decades from something that people have to something that people do, thereby stimulating research on how vocal charisma can be created and improved. Broadening the perspective on vocal charisma beyond the speaker’s performance itself to the context of the speech, we conducted acoustic-prosodic analyses of public speeches of two prominent Israelian politicians – Benjamin Netanyahu and Benny Gantz. The speech material consisted of 311–516 prosodic phrases per politician from the election campaigns 2019–2020 and, crucially, was balanced so as to include an equal number of pre- and post-election speeches. Results show a superiority of Netanyahu over Gantz in almost all facets of vocal charisma, although Gantz caught up over time. Moreover, unlike Gantz, Netanyahu showed a strong adaptation of his vocal charisma patterns to before- and after-election contexts. Scrutinizing this versatility difference, an additional perception experiment with 42 listeners and excerpts from the two politicians’ speeches was carried out. Results show that Netanyahu’s speech excerpts were, unlike those of Gantz, mainly rated as more charismatic in those contexts in which they were performed. Gantz’ post-election speech excerpts, by contrast, were primarily rated as not fitting into that context, i.e., as unfolding their charisma better in a pre-election context. Moreover, listeners also rated Netanyahu as overall more charismatic than Gantz. The combined production and perception evidence suggests the relevance of context in the evaluation and interpretation of vocal charisma signals.

How Are You Feeling Today?

This piece of creative writing explores the possible impact of emotional artificial intelligence (EAI), a variety of technologies which have the common aim of inferring human emotion from outward expressions such as facial expressions, vocal patterns, text, and physiological data. It is difficult to determine exactly how EAI might affect people when thinking in the abstract. We therefore took a collaborative approach, combining the imagination and writing skills of a Sci-Fi writer, with the knowledge base of an academic studying EAI, in order to create a story which makes the potential consequences of EAI real in a tangible way. Some readers may have prior knowledge of EAI, and for you we hope this piece can offer new insights or different perspectives to consider. However, we suspect many readers will not have heard of EAI and be considering it here for the first time. For you, we hope to provide a story which you can truly immerse yourself in, which can act as a prompt for you to begin to consider your views on this technology. EAI may be at a relatively early stage of development, but we do not anticipate it being long before it is a widespread technology. Our prompt as writers was to create an imagined surveillance future. Our invitation to you as readers is to not only imagine it, but ponder it, live in it, question it, and, ultimately, shape it.

Feel the beat: cape fur seal males encode their arousal state in their bark rate.

The cape fur seal is one of the most colonial mammal species in the world. Breeding colonies are composed of harems held by mature males (older than 10years) with up to 30 females and their pups, while roaming subadult males (younger and socially immature) are kept away from bulls' territories. As in other pinnipeds, cape fur seals are highly vocal and use acoustic signals in all their social interactions. Males produce barks-short vocalizations always produced in sequences-for territorial defense, mating behaviors, and agonistic interactions. These calls convey information about the sex, age class, and individual identity. This study investigated whether motivational cues such as the arousal state can be encoded in territorial males' barks and whether these cues are decoded by listening sub-adult males. The rate (number of calls per unit of time) and fundamental frequency of barks were found to significantly increase during high arousal state interactions (i.e., male-male confrontation) compared to spontaneous barks. Playback experiments revealed that subadult males responded with a higher level of vigilance when territorial males' barks had a faster bark rate. This mechanism of decoding the bulls' arousal state from barks will likely constitute an advantage for both bulls and the subadult males, by avoiding or reducing physical conflicts, and thereby reducing energy expenditure and the risk of injury. This study is the first experimental evidence of cape fur seals' using vocal rhythmic patterns to modulate their social interactions.

Social pressure drives "conversational rules" in great apes.

In the last decade, two hypotheses, one on the evolution of animal vocal communication in general and the other on the origins of human language, have gained ground. The first hypothesis argues that the complexity of communication co-evolved with the complexity of sociality. Species forming larger groups with complex social networks have more elaborate vocal repertoires. The second hypothesis posits that the core of communication is represented not only by what can be expressed by an isolated caller, but also by the way that vocal interactions are structured, language being above all a social act. Primitive forms of conversational rules based on a vocal turn-taking principle are thought to exist in primates. To support and bring together these hypotheses, more comparative studies of socially diverse species at different levels of the primate phylogeny are needed. However, the majority of available studies focus on monkeys, primates that are distant from the human lineage. Great apes represent excellent candidates for such comparative studies because of their phylogenetic proximity to humans and their varied social lives. We propose that studying vocal turn-taking in apes could address several major gaps regarding the social relevance of vocal turn-taking and the evolutionary trajectory of this behaviour among anthropoids. Indeed, how the social structure of a species may influence the vocal interaction patterns observed among group members remains an open question. We gathered data from the literature as well as original unpublished data (where absent in the literature) on four great ape species: chimpanzees Pan troglodytes, bonobos Pan paniscus, western lowland gorillas Gorilla gorilla gorilla and Bornean orang-utans Pongo pygmaeus. We found no clear-cut relationship between classical social complexity metrics (e.g. number of group members, interaction rates) and vocal complexity parameters (e.g. repertoire size, call rates). Nevertheless, the nature of the society (i.e. group composition, diversity and valence of social bonds) and the type of vocal interaction patterns (isolated calling, call overlap, turn-taking-based vocal exchanges) do appear to be related. Isolated calling is the main vocal pattern found in the species with the smallest social networks (orang-utan), while the other species show vocal interactions that are structured according to temporal rules. A high proportion of overlapping vocalisations is found in the most competitive species (chimpanzee), while vocal turn-taking predominates in more tolerant bonobos and gorillas. Also, preferentially interacting individuals and call types used to interact are not randomly distributed. Vocal overlap ('chorusing') and vocal exchange ('conversing') appear as possible social strategies used to advertise/strengthen social bonds. Our analyses highlight that: (i) vocal turn-taking is also observed in non-human great apes, revealing universal rules for conversing that may be deeply rooted in the primate lineage; (ii) vocal interaction patterns match the species' social lifestyle; (iii) although limited to four species here, adopting a targeted comparative approach could help to identify the multiple and subtle factors underlying social and vocal complexity. We believe that vocal interaction patterns form the basis of a promising field of investigation that may ultimately improve our understanding of the socially driven evolution of communication.

Amphibian behavioral diversity offers insights into evolutionary neurobiology.

Recent studies have served to emphasize the unique placement of amphibians, composed of more than 8000 species, in the evolution of the brain. We provide an overview of the three amphibian orders and their respective ecologies, behaviors, and brain anatomy. Studies have probed the origins of independently evolved parental care strategies in frogs and the biophysical principles driving species-specific differences in courtship vocalization patterns. Amphibians are also important models for studying the central control of movement, especially in the context of the vertebrate origin of limb-based locomotion. By highlighting the versatility of amphibians, we hope to see a further adoption of anurans, urodeles, and gymnophionans as model systems for the evolution and neural basis of behavior across vertebrates.

The transition from the female-like great calls to male calls during ontogeny in southern yellow-cheeked gibbon males (Nomascus gabriellae)

It is well known that gibbons emit a pattern of vocalizations, which is specific for species and sex. A previous study showed, however, that immature southern yellow-cheeked gibbon (Nomascus gabriellae) males produce only female-like great calls from 2.3 to 5.3 years of age in co-singing interactions with their mothers. To date, nothing is known about how the vocal repertoire of a male changes from the female-like call (great call) to the male call (staccato notes and multi-modulation phrase) during vocal ontogeny. The goal of this study was to describe the transition from the female-like great call to the male call and the ontogeny of the male call. We predicted that the transition from the female-like great call to the male-specific call and the development of the male call is a normal part of the aging proces. If this is the case, the following phenomena will occur: (a) female vocalization should no longer be produced with the mature form of the multi-modulation phrase and (b) all stages of the male vocalization should occur gradually as the young male ages. Young males regularly emit both female-like great calls and male-specific calls between the ages of 5.6 to 7.1 years. Once the young males reached 7.1 years of age, they emitted male calls exclusively, and they continued to do so until the end of the observation period (at 8.11 years of age). It was confirmed that the young males emitted only female-like great calls during periods when they produced non-mature forms of a multi-modulation phrase (Fm0,1—none or one frequency modulation in second notes). Furhermore, the decrease in the number of female-like great calls was attributed to the development of the mature form of the multi-modulation phrase (Fm2—two or more frequency modulation in second notes), which developed with age. We also confirmed that the multi-modulation phrase developed gradually, while the development of the staccato notes occurred in leaps. A multi-modulation phrase developed as the initial part of the male-specific call. It was evolved from a simpler to a more complex form as the maximum frequency and age of the young males increased. Staccato notes subsequently developed in certain young males. Possible explanations for such vocal ontogeny in young males are discussed in this work.