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Phonological memory, or the ability to remember a novel word string well enough to repeat it, has long been characterized as a time-limited store. An alternative embodiment model sees it as the product of the dynamic sensorimotor (perceptual and production) processes that inform responses to speech. Keren-Portnoy et al. (2010) demonstrated that this capacity, often tested through nonword repetition and found to predict lexical advance, is itself predicted by the first advances in babbling. Pursuing the idea that phonological memory develops through vocal production, we trace its development-drawing on illustrative data from children learning six languages-from the earliest adult-like vocalizations through to the first words and the consolidation of early words into an initial lexical network and more stable representational capacity. We suggest that it is the interaction of perceptual and production experience that mediates the mapping of new forms onto lexical representations. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

n accordance with the current Vasiljević method, model songs and songs for special occasions are the starting point in the process of developing students’ music literacy. At the same time, these songs are used for developing students’ voice. In order to investigate the methodological functionality of the model songs and songs for special occasions, we analyzed the textbooks of eight publishing houses (Zavod za udžbenike, Klet, Vulkan, Eduka, Bigz, Novi logos, Freska, Kreativni centar). The results indicate that the textbooks mostly contain the models recommended in the curriculum, but that the models are often composed by the textbook authors themselves with a didactic purpose. It was also observed that the authors in the textbook literature, especially in the first-grade textbooks, do not follow the methodological guidelines of the Vasiljević method in terms of working on the development of the voice volume. In order to point to the ethnomusicological material as a good source for the selection of songs, we first explained the procedures for adapting the songs from the ethnomusicological material, and then provided several models and songs for special occasions. The aim of the research is to improve the lessons of music literacy in primary schools in Serbia using the Vasiljević method and to point out the importance of folk songs as basic and initial music material, both for the music literacy of children and for vocal development. The researchers used the method of theoretical content analysis. The implications of the research refer to raising the professional competence of primary school teachers in the selection of music material for teaching music literacy, the design of operational curricula, familiarization of the wider academic public with the importance of adapting musical material from ethnomusicological collections, the improvement of work in schools and teacher training colleges in terms of an adequate application of the Vasiljević method.

Wild cheetahs Acinonyx jubatus of all age classes, from newborns to adults, use their long‐distance chirps for communication with conspecifics. We investigated the ontogenetic changes of eight acoustic parameters of the chirps produced by wild‐living cheetahs across 14 age classes in Kenya. Chirp maximum fundamental frequency (f0max) was found to be best acoustic correlate of cheetah age. The f0max was the highest in neonates (up to 10 kHz), then decreased steadily across age classes and reached a plateau of about 1 kHz in mature adults older than 4 years. Based on a close relationship of f0max with age, we fitted polynomial models for estimating cheetah age by their chirps. We discuss that gradual changes of chirp f0max suggest the gradual development of cheetah vocal apparatus. Model for age estimation by chirps in the cheetah proposed in this study may provide conservationists a non‐invasive bioacoustic tool for estimating cheetah age, particularly at ages younger than 4 years. However, introducing more data from cheetahs of precisely known age would be necessary for obtaining more accurate results of age determination by voice for the older individuals. [ABSTRACT FROM AUTHOR]

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Introduction: The fundamental frequency contour (melody) of cry and non-cry utterances becomes more complex with age. However, there is a lack of longitudinal analyses of melody development during the first year of life. Objective: The aim of the study was to longitudinally analyze melody development in typical vocalization types across the first 12 months of life. The aim was twofold: (1) to answer the question whether melody becomes more complex in all vocalization types with age and (2) to characterize complex patterns in more detail. Methods: Repeatedly recorded vocalizations (n = 10,988) of 10 healthy infants (6 female) over their first year of life were analyzed using frequency spectrograms and fundamental frequency (f0) analyses (PRAAT). Melody complexity analysis was performed using specific in-lab software (CDAP, pw-project) in a final subset of 9,237 utterances that contained noise-free, undisturbed contours. Generalized mixed linear models were used to analyze age and vocalization type effects on melody complexity. Results: The vocalization repertoire showed a higher proportion of complex melodies from the second month onward. The age effect was significant, but no difference was found in melody complexity between cry and non-cry vocalizations across the first 6 months. From month 7–12, there was a further significant increase in complex structures only in canonical babbling not in marginal babbling. Melody segmentations by laryngeal constrictions prevailed among complex shapes. Conclusion: The study demonstrated the regularity of melody development in different vocalization types throughout the first year of life. In terms of prosodic features of infant sounds, melody contour is of primary importance, and further studies are required that also include infants at risk for language development. [ABSTRACT FROM AUTHOR]

Acoustic parameters of spotted seals (Phoca largha), including the duration, peak frequency, and peak-to-peak source level, are reported to vary between different ages and sexes; however, to our knowledge, the vocal ontogeny of the spotted seal from newborn to 1 year old is yet to be studied. In the present study, we recorded and analyzed vocalizations of human-cared spotted seals from the Liaodong Bay colony from newborn to 1 year old, aiming to document the first-year development of seal vocalizations. We divided the spotted seal pups into four age groups (i.e., 1–3-month, 4–6-month, 7–9-month, and 10–12-month groups) for both sexes. The results show significant differences in sex patterns in sound parameters in terms of duration, peak frequency, and peak-to-peak source level. The vocalizations of female seal pups were longer in duration but lower in peak frequency and peak-to-peak source level than those of male pups. All three sound parameters were significantly different across different age groups. Specifically, the 1–3-month group had significantly lower values in duration, peak frequency, and peak-to-peak source level than the three other age groups. The 10–12-month group had significantly higher values in duration and peak-to-peak source level than the three other age groups. Our results also indicate a sex-specific development pattern of seal vocalizations from 1 year old until sexual maturity. Our findings will benefit the evaluation of anthropogenic noise impacts on spotted seal pups and further conservation of the seal population.

Through micro-genetic analysis of early singing, I describe and explain the complexity of song as an elementary cultural expression. For educators, it is important to understand the key role of song with and by young children as a means to convey feelings and musico-linguistic rules. Song consists of melody and lyrics, both of which are connected by metrical rules to form a Gestalt. A song sung by 18-month-old Lynn exemplifies that she produces the melody with ease, but shows difficulty forming the words. By following rules, she forms and expresses feelings of belonging to those who shared their singing with her previously. [ABSTRACT FROM AUTHOR]

Objective: This study investigated vocalization and language environment longitudinally in infants with cleft palate (CP) based on day-long audio recordings collected in their natural environments. Design: Language Environment Analysis (LENA) data from all-day recordings at home were collected at 3-month intervals for infants from 4-6 to 16-18 months of age. The recordings were analyzed using experimentally blinded human coding as well as LENA automated analysis. Participants: Ten infants with CP (± cleft lip) and 10 age-matched infants without CP. Main Outcome Measures: Several measurements were obtained from the LENA automated analysis software. In addition, human coded measurements of vocalization and language environment, including the true canonical babbling ratio and the infant-directed speech ratio, were analyzed for each time point of data collection for each infant. Statistical analyses were performed to conduct group and age comparisons for each measure of vocalization and language environment. Results: No group differences emerged in number of syllables produced. Infants with CP exhibited late onset and fewer productions of canonical syllables compared to infants without CP. Infants with CP did not show significant differences from infants without CP in measures related to language environment across ages. Conclusion: This study provides detailed information through naturalistic all-day home recordings about vocal development and early language environments in infants with CP before and after palatal repair. Clinical implications for early intervention are discussed. [ABSTRACT FROM AUTHOR]

Abstract Background Rodents are thought to be produced their human-audible calls (AUDs, below 20 kHz) with phonation mechanism based on vibration of the vocal folds, whereas their ultrasonic vocalizations (USVs, over 20 kHz) are produced with aerodynamic whistle mechanism. Despite of different production mechanisms, the acoustic parameters (duration and fundamental frequency) of AUDs and USVs change in the same direction along ontogeny in collared lemming Dicrostonyx groenlandicus and fat-tailed gerbil Pachyuromys duprasi. We hypothesize that this unidirectional trend of AUDs and USVs is a common rule in rodents and test whether the AUDs of yellow steppe lemmings Eolagurus luteus would display the same ontogenetic trajectory (towards shorter and low-frequency calls) as their USVs, studied previously in the same laboratory colony. Results We examined for acoustic variables 1200 audible squeaks emitted during 480-s isolation-and-handling procedure by 120 individual yellow steppe lemmings (at 12 age classes from neonates to breeding adults, 10 individuals per age class, up to 10 calls per individual, each individual tested once). We found that the ontogenetic pathway of the audible squeaks, towards shorter and lower frequency calls, was the same as the pathway of USVs revealed during 120-s isolation procedure in a previous study in the same laboratory population. Developmental milestone for the appearance of mature patterns of the squeaks (coinciding with eyes opening at 9–12 days of age), was the same as previously documented for USVs. Similar with ontogeny of USVs, the chevron-like squeaks were prevalent in neonates whereas the squeaks with upward contour were prevalent after the eyes opening. Conclusion This study confirms a hypothesis of common ontogenetic trajectory of call duration and fundamental frequency for AUDs and USVs within species in rodents. This ontogenetic trajectory is not uniform across species.

Birds often vocalize when threatened or captured by a predator. We present detailed qualitative analyses of calls from 24 red-capped plover (Charadrius ruficapillus) and 117 masked lapwing (Vanellus miles) chicks (Charadriidae) that we recorded during handling. Calls were structurally complex and differed between species. Calls showed moderate structure at higher levels of organization (e.g., similarity between successive calls; sequential grading). Some call characteristics resembled those in other bird species in similar circumstances (e.g., in nonlinear phenomena). Most calls consisted of several different parts, which combined in different ways across calls. Past studies have overlooked most features of distress calls and calling in charadriids due to small sample sizes and limited spectrographic analyses. Understanding interspecific patterns in call structure, and determination of call functions, will require: detailed knowledge of natural history; detailed behavioural descriptions, acoustic analysis, and analyses of development and growth; and experimental investigations of call functions. [ABSTRACT FROM AUTHOR]

Acoustic communication is critical during early life phases in precocial birds; for example, adult alarm calls can elicit antipredator behaviour in young, and chick vocalizations can communicate information to parents about chick identity, condition, location, sex or age. We opportunistically recorded Red‐capped Plover Charadrius ruficapillus and Southern Masked Lapwing Vanellus miles novaehollandiae distress calls of chicks while they were in the hand and analysed the calls to determine whether call structure is related to sex or body mass (a proxy for age). Our study provides the first evidence for charadriid chicks of (1) a sexual difference in call structure and rate and (2) gradual growth‐related changes in call structure and rate, across chicks. We provide a foundation for further studies of shorebird vocalizations during growth, which may elucidate the development and functional significance of such vocalizations. [ABSTRACT FROM AUTHOR]

Adult behaviors, such as vocal production, often exhibit temporal regularity. In contrast, their immature forms are more irregular. We ask whether the coupling of motor behaviors with arousal changes gives rise to temporal regularity: Do they drive the transition from variable to regular motor output over the course of development? We used marmoset monkey vocal production to explore this putative influence of arousal on the nonlinear changes in their developing vocal output patterns. Based on a detailed analysis of vocal and arousal dynamics in marmosets, we put forth a general model incorporating arousal and auditory feedback loops for spontaneous vocal production. Using this model, we show that a stable oscillation can emerge as the baseline arousal increases, predicting the transition from stochastic to periodic oscillations observed during marmoset vocal development. We further provide a solution for how this model can explain vocal development as the joint consequence of energetic growth and social feedback. Together, we put forth a plausible mechanism for the development of arousal-mediated adaptive behavior. NEW & NOTEWORTHY The development of motor behaviors, and the influence of energetic and social factors on it, has long been of interest, yet we lack an integrated picture of how these different systems may interact. Through the lens of vocal devel- opment in infant marmosets, this study offers a solution for social behavior development by linking motor production with arousal states. Increases in arousal can drive the system out of stochastic states toward oscillatory dynamics ready for communication. [ABSTRACT FROM AUTHOR]

While the vocalizations of non-human primates were thought to be innate, recent studies have revealed highly flexible vocalizations in immatures. This behavior suggests that social influences have an important role in developing vocalizations. Yet not much is known about how non-human primate vocalization develop and how the vocalizations of immature animals differ between sexes. Here, we analyzed 95 cases of co-singing between mothers and offspring out of 240 female songs from three groups of wild Javan gibbon (Hylobates moloch) in Gunung Halimun-Salak National Park, Indonesia, between 2009 and 2021. Hylobates moloch is one of only two gibbon species with pairs that do not duet. Instead, they produce sex-specific solo songs. We found that both offspring female and male H. moloch follow their mothers’ female-specific songs, similar to other duetting gibbon species. Immatures started co-singing with their mothers from 7 months old, but with an average starting age of about 24 months. As female offspring grew older, they co-sung with mothers more often while male offspring did not. After 7 years of age, both sexes stopped co-singing with their mothers and started singing alone, following their own sex-specific vocalizations. We did not find any relation between male offspring co-singing and territorial functions (e.g., co-singing more during intergroup encounters or closer to home range borders). Our results suggest that mothers’ songs may trigger male offspring and females to practice singing, but not specifically for males to defend territories. We highlight that despite the absence of duets, H. moloch develop their vocalizations from early infancy and throughout their maturation while co-singing with mothers. However, the level of co-singing varies depending on the sexes. Our study is the first to elucidate the sex-specific trajectories of vocal development in H. moloch across years, indicating that offspring in non-duetting gibbons co-sing with mothers like in duetting species.

Human and non-human primates produce rhythmical sounds as soon as they are born. These early vocalizations are important for soliciting the attention of caregivers. How they develop remains a mystery. The orofacial movements necessary for producing these vocalizations have distinct spatiotemporal signatures. Therefore, their development could potentially be tracked over the course of prenatal life. We densely and longitudinally sampled fetal head and orofacial movements in marmoset monkeys using ultrasound imaging. We show that orofacial movements necessary for producing rhythmical vocalizations differentiate from a larger movement pattern that includes the entire head. We also show that signature features of marmoset infant contact calls emerge prenatally as a distinct pattern of orofacial movements. Our results establish that aspects of the sensorimotor development necessary for vocalizing occur prenatally, even before the production of sound.

In many songbird species, young birds learn their song from adult conspecifics. Like much animal communication, birdsong is multimodal: singing is accompanied by beak and body movements. We hypothesized that these visual cues could enhance vocal learning thus partly explaining the reduced learning from unimodal audio playbacks compared to multimodal live social tutoring observed in many birdsong studies. To test this, juvenile zebra finches, Taeniopygia guttata , were tutored in a yoked design where replicate tutoring groups of three male–female dyads were exposed to the same live tutor simultaneously in three different ways. (1) Tutees were housed with the tutor in a central compartment; hence they could hear, see and interact with their tutor ('live'). (2) Tutees placed in one of two adjacent compartments could hear but not see the same tutor from behind a black loudspeaker cloth ('audio-only'). (3) Tutees could likewise hear the tutor through loudspeaker cloth but could also see the tutor through a one-way mirror ('audiovisual'). Comparisons of subadult and adult song showed more changes in the audio-only than in the audiovisual or live tutored tutees, suggesting the audio-only group's song development was delayed. According to (blinded) human observer similarity scoring, the audio-only tutees' singing was least similar and the live tutees' singing most similar to their tutor's singing, while the audiovisual tutees showed an intermediate level of similarity, but the between-treatment differences in similarity were not significant. Conversely, the audio-only group showed the highest similarity values with their father's song, which they only heard before the experimental tutoring. Given that the quantity and quality of the tutor song input were the same across treatments within tutoring groups, the results support the hypothesis that visual in addition to auditory exposure to a tutor can affect the timing and possibly also the amount of vocal learning. • We tested why young birds often learn better from live tutors than audio playback. • Young zebra finches were either housed with, could see and hear or only hear a tutor. • Birds only hearing but not seeing a tutor kept changing aspects of song for longer. • Similarity to tutor song in adulthood varied more across individuals than groups. • Visual cues affected developmental trajectories more than they did copying song units. [ABSTRACT FROM AUTHOR]

Bird song and human speech are learned early in life and for both cases engagement with live social tutors generally leads to better learning outcomes than passive audio-only exposure. Real-world tutor–tutee relations are normally not uni- but multimodal and observations suggest that visual cues related to sound production might enhance vocal learning. We tested this hypothesis by pairing appropriate, colour-realistic, high frame-rate videos of a singing adult male zebra finch tutor with song playbacks and presenting these stimuli to juvenile zebra finches (Taeniopygia guttata). Juveniles exposed to song playbacks combined with video presentation of a singing bird approached the stimulus more often and spent more time close to it than juveniles exposed to audio playback only or audio playback combined with pixelated and time-reversed videos. However, higher engagement with the realistic audio–visual stimuli was not predictive of better song learning. Thus, although multimodality increased stimulus engagement and biologically relevant video content was more salient than colour and movement equivalent videos, the higher engagement with the realistic audio–visual stimuli did not lead to enhanced vocal learning. Whether the lack of three-dimensionality of a video tutor and/or the lack of meaningful social interaction make them less suitable for facilitating song learning than audio–visual exposure to a live tutor remains to be tested. [ABSTRACT FROM AUTHOR]

This study attempted to search the nature of language development and the relationship between vocal development and motor development in infancy, and it relied on the descriptive and qualitative approach and the method of content analysis to review and compare three researches related to the relationship of language development and physical development during language learning in the infancy. The results of the three studies, despite some difference between them, indicates the relationship between sound, movement, and body signals before, during and after language learning in infancy. [ABSTRACT FROM AUTHOR]

Background: Our goal was to assess for the first time early vocalizations as precursors to speech in audio-video recordings of infants with tuberous sclerosis complex (TSC).Methods: We randomly selected 40 infants with TSC from the TSC Autism Center of Excellence Research Network dataset. Using human observers, we analyzed 74 audio-video recordings within a flexible software-based coding environment. During the recordings, infants were engaged in developmental testing. We determined syllables per minute (volubility), the number of consonant-vowel combinations, such as 'ba' (canonical babbling), and the canonical babbling ratio (canonical syllables/total syllables) and compared the data with two groups of typically developing (TD) infants. One comparison group's data had come from a laboratory setting, while the other's had come from all-day Language Environment Analysis recordings at home.Results: Compared with TD infants in laboratory and all-day Language Environment Analysis recordings, entry into the canonical babbling stage was delayed in the majority of infants with TSC, and the canonical babbling ratio was low (TD mean = 0.346, SE = 0.19; TSC mean = 0.117, SE = 0.023). Volubility level in infants with TSC was less than half that of TD infants (TD mean = 9.82, SE = 5.78; TSC mean = 3.99, SE = 2.16).Conclusions: Entry into the canonical stage and other precursors of speech development were delayed in infants with TSC and may signal poor language and developmental outcomes. Future studies are planned to assess prediction of language and developmental outcomes using these measures in a larger sample and in more precisely comparable recording circumstances. [ABSTRACT FROM AUTHOR]

For over a century, the evolution of animal play has sparked scientific curiosity. The prevalence of social play in juvenile mammals suggests that play is a beneficial behavior, potentially contributing to individual fitness. Yet evidence from wild animals supporting the long-hypothesized link between juvenile social play, adult behavior, and fitness remains limited. In Western Australia, adult male bottlenose dolphins ( Tursiops aduncus ) form multilevel alliances that are crucial for their reproductive success. A key adult mating behavior involves allied males using joint action to herd individual females. Juveniles of both sexes invest significant time in play that resembles adult herding-taking turns in mature male (actor) and female (receiver) roles. Using a 32-y dataset of individual-level association patterns, paternity success, and behavioral observations, we show that juvenile males with stronger social bonds are significantly more likely to engage in joint action when play-herding in actor roles. Juvenile males also monopolized the actor role and produced an adult male herding vocalization ("pops") when playing with females. Notably, males who spent more time playing in the actor role as juveniles achieved more paternities as adults. These findings not only reveal that play behavior provides male dolphins with mating skill practice years before they sexually mature but also demonstrate in a wild animal population that juvenile social play predicts adult reproductive success., Competing Interests: Competing interests statement:The authors declare no competing interest.

Human infant vocalization is viewed as a critical foundation for vocal learning and language. All apes share distress sounds (shrieks and cries) and laughter. Another vocal type, speech-like sounds, common in human infants, is rare but not absent in other apes. These three vocal types form a basis for especially informative cross-species comparisons. To make such comparisons possible we need empirical research documenting the frequency of occurrence of all three. The present work provides a comprehensive portrayal of these three vocal types in the human infant from longitudinal research in various circumstances of recording. Recently, the predominant vocalizations of the human infant have been shown to be speech-like sounds, or 'protophones', including both canonical and non-canonical babbling. The research shows that protophones outnumber cries by a factor of at least five based on data from random-sampling of all-day recordings across the first year. The present work expands on the prior reports, showing the protophones vastly outnumber both cry and laughter in both all-day and laboratory recordings in various circumstances. The data provide new evidence of the predominance of protophones in the infant vocal landscape and illuminate their role in human vocal learning and the origin of language. This article is part of the theme issue 'Vocal learning in animals and humans'. [ABSTRACT FROM AUTHOR]

Human vocal development and speech learning require acoustic feedback, and humans who are born deaf do not acquire a normal adult speech capacity. Most other mammals display a largely innate vocal repertoire. Like humans, bats are thought to be one of the few taxa capable of vocal learning as they can acquire new vocalizations by modifying vocalizations according to auditory experiences. We investigated the effect of acoustic deafening on the vocal development of the pale spear-nosed bat. Three juvenile pale spear-nosed bats were deafened, and their vocal development was studied in comparison with an age-matched, hearing control group. The results show that during development the deafened bats increased their vocal activity, and their vocalizations were substantially altered, being much shorter, higher in pitch, and more aperiodic than the vocalizations of the control animals. The pale spear-nosed bat relies on auditory feedback for vocal development and, in the absence of auditory input, species-atypical vocalizations are acquired. This work serves as a basis for further research using the pale spear-nosed bat as a mammalian model for vocal learning, and contributes to comparative studies on hearing impairment across species. This article is part of the theme issue 'Vocal learning in animals and humans'. [ABSTRACT FROM AUTHOR]

Background: Rodents are thought to be produced their human-audible calls (AUDs, below 20 kHz) with phonation mechanism based on vibration of the vocal folds, whereas their ultrasonic vocalizations (USVs, over 20 kHz) are produced with aerodynamic whistle mechanism. Despite of different production mechanisms, the acoustic parameters (duration and fundamental frequency) of AUDs and USVs change in the same direction along ontogeny in collared lemming Dicrostonyx groenlandicus and fat-tailed gerbil Pachyuromys duprasi. We hypothesize that this unidirectional trend of AUDs and USVs is a common rule in rodents and test whether the AUDs of yellow steppe lemmings Eolagurus luteus would display the same ontogenetic trajectory (towards shorter and low-frequency calls) as their USVs, studied previously in the same laboratory colony. Results: We examined for acoustic variables 1200 audible squeaks emitted during 480-s isolation-and-handling procedure by 120 individual yellow steppe lemmings (at 12 age classes from neonates to breeding adults, 10 individuals per age class, up to 10 calls per individual, each individual tested once). We found that the ontogenetic pathway of the audible squeaks, towards shorter and lower frequency calls, was the same as the pathway of USVs revealed during 120-s isolation procedure in a previous study in the same laboratory population. Developmental milestone for the appearance of mature patterns of the squeaks (coinciding with eyes opening at 9–12 days of age), was the same as previously documented for USVs. Similar with ontogeny of USVs, the chevron-like squeaks were prevalent in neonates whereas the squeaks with upward contour were prevalent after the eyes opening. Conclusion: This study confirms a hypothesis of common ontogenetic trajectory of call duration and fundamental frequency for AUDs and USVs within species in rodents. This ontogenetic trajectory is not uniform across species. [ABSTRACT FROM AUTHOR]

Despite the important role that vocal communication plays in the social lives of nearly all mammals, few studies have documented the emergence and development of acoustic behavior within individuals throughout their lifetimes. It is even less common to examine learned vs innate aspects of vocal development in long-lived mammals. In this study, we routinely monitored spontaneous vocalizations produced by a male Pacific harbor seal (Phoca vitulina) and a female northern elephant seal (Mirounga angustirostris) raised in human care without conspecific individuals for more than 18 years. We used these unique longitudinal datasets to assess whether the call characteristics of captive individuals resembled those of wild conspecific seals. Additionally, we marked the developmental onset and seasonal timing of vocal activity to determine whether initial vocal expression coincided with reproductive maturity and to evaluate whether temporal patterns in vocal activity were similar across years. We found that resemblance of vocal behavior to that of wild individuals varied between subjects. Both seals showed appropriate maturational timing of vocal behavior associated with reproductive status. The male harbor seal showed a species-typical template for vocal production, whereas the female northern elephant seal produced calls with structure that differed considerably from those of wild individuals. These two case studies provide information relevant to ongoing studies on the ontogeny of sound production and the role that learning plays in vocal behavior. [ABSTRACT FROM AUTHOR]

This study evaluates whether early vocalizations develop in similar ways in children across diverse cultural contexts. We analyze data from daylong audio recordings of 49 children (1–36 months) from five different language/cultural backgrounds. Citizen scientists annotated these recordings to determine if child vocalizations contained canonical transitions or not (e.g., "ba" vs. "ee"). Results revealed that the proportion of clips reported to contain canonical transitions increased with age. Furthermore, this proportion exceeded 0.15 by around 7 months, replicating and extending previous findings on canonical vocalization development but using data from the natural environments of a culturally and linguistically diverse sample. This work explores how crowdsourcing can be used to annotate corpora, helping establish developmental milestones relevant to multiple languages and cultures. Lower inter‐annotator reliability on the crowdsourcing platform, relative to more traditional in‐lab expert annotators, means that a larger number of unique annotators and/or annotations are required, and that crowdsourcing may not be a suitable method for more fine‐grained annotation decisions. Audio clips used for this project are compiled into a large‐scale infant vocalization corpus that is available for other researchers to use in future work. [ABSTRACT FROM AUTHOR]

Introduction: Perception and memorizing of melody and rhythm start about the third trimester of gestation. Infants have astonishing musical predispositions, and melody contour is most salient for them. Objective: To longitudinally analyse melody contour of spontaneous crying of healthy infants and to identify melodic intervals. The aim was 3-fold: (1) to answer the question whether spontaneous crying of healthy infants regularly exhibits melodic intervals across the observation period, (2) to investigate whether interval events become more complex with age and (3) to analyse interval size distribution. Methods: Weekly cry recordings of 12 healthy infants (6 females) over the first 4 months of life were analysed (6,130 cry utterances) using frequency spectrograms and pitch analyses (PRAAT). A preselection of utterances containing a well-identifiable, noise-free and undisturbed melodic contour was applied to identify and measure melodic intervals in the final subset of 3,114 utterances. Age-dependent frequency of occurrence of melodic intervals was statistically analysed using generalized estimating equations. Results: 85.3% of all preselected melody contours (n = 3,114) either contained single rising or falling melodic intervals or complex events as combinations of both. In total 6,814 melodic intervals were measured. A significant increase in interval occurrence was found characterized by a non-linear age effect (3 developmental phases). Complex events were found to significantly increase linearly with age. In both calculations, no sex effect was found. Interval size distribution showed a maximum of the minor second as the prevailing musical interval in infants' crying over the first 4 months of life. Conclusion: Melodic intervals seem to be a regular phenomenon of spontaneous crying of healthy infants. They are suggested to be a further candidate for developing an early risk marker of vocal control in infants. Subsequent studies are needed to compare healthy infants and infants at risk for respiratory-laryngeal dysfunction to investigate the diagnostic value of the occurrence of melodic intervals and their age-depending complexification. [ABSTRACT FROM AUTHOR]

Birds are our best models to understand vocal learning – a vocal production ability guided by auditory feedback, which includes human language. Among all vocal learners, songbirds have the most diverse life histories, and some aspects of their vocal learning ability are well-known, such as the neural substrates and vocal control centers, through vocal development studies. Currently, species are classified as either vocal learners or non-learners, and a key difference between the two is the development period, extended in learners, but short in non-learners. But this clear dichotomy has been challenged by the vocal learning continuum hypothesis. One way to address this challenge is to examine both learners and canonical non-learners and determine whether their vocal development is dichotomous or falls along a continuum. However, when we examined the existing empirical data we found that surprisingly few species have their vocal development periods documented. Furthermore, we identified multiple biases within previous vocal development studies in birds, including an extremely narrow focus on (1) a few model species, (2) oscines, (3) males, and (4) songs. Consequently, these biases may have led to an incomplete and possibly erroneous conclusions regarding the nature of the relationships between vocal development patterns and vocal learning ability. Diversifying vocal development studies to include a broader range of taxa is urgently needed to advance the field of vocal learning and examine how vocal development patterns might inform our understanding of vocal learning.

The zebra finch (Taeniopygia guttata) is a socially monogamous and colonial opportunistic breeder with pronounced sexual differences in singing and plumage coloration. Its natural history has led to it becoming a model species for research into sex differences in vocal communication, as well as behavioral, neural and genomic studies of imitative auditory learning. As scientists tap into the genetic and behavioral diversity of both wild and captive lineages, the zebra finch will continue to inform research into culture, learning, and social bonding, as well as adaptability to a changing climate.

This study explores vocal development as an early marker of autism, focusing on canonical babbling rate and onset, typically established by 7 months. Previous reports suggested delayed or reduced canonical babbling in infants later diagnosed with autism, but the story may be complicated. We present a prospective study on 44 infants later diagnosed with autism spectrum disorder compared with 127 infants later identified as typically developing who were followed longitudinally with day-long recordings from 0 to 13 months. Eight 5-min segments from each of their recordings were coded for canonical and noncanonical syllables. The results confirmed many reports that canonical babbling is a robust feature of human vocal development in the first year of life, with small overall mean differences in canonical babbling rates between the autism spectrum disorder and typically developing groups beginning around 9 months, primarily in males. Our findings highlight the importance of considering sex differences in vocal communication as part of the early detection and diagnosis of autism when determining the need for communication supports to maximize outcomes.Our study examined how babies develop their ability to talk to help identify early signs of autism. We looked at babies’ production of babbling with mature syllables across the first year of life. Babies usually start producing mature babbling at 7 months of age before they say their first words. Some studies have suggested that babies who are later diagnosed with autism produce this kind of babbling less frequently in their first year of life, but other studies have shown complicated outcomes. In this new study, we followed 44 autistic babies and compared them to 127 typically developing babies. We recorded the babies once every month, all day long, from the time that they were born until they were around 13 months old. Then, we studied their mature babbling from segments of these recordings. We found that the rate at which babies used mature babbling was lower in boys with autism, and higher in girls with autism, compared to babies without autism. This research helps us understand how babies with autism learn to talk. It also raises important questions about differences between boys and girls with autism. Our study can help us improve how scientists and clinicians can identify autism earlier, which could lead to better communication supports for autistic children and their families. [ABSTRACT FROM AUTHOR]

This study investigates vocal development of nestling kea parrots (Nestor notabilis). First, we examine how many structurally distinct call types were present during the nestling period, and the age in which call types occurred. Based on studies with other avian species, we predicted that kea nestlings would have multiple call types, with some present at hatching and others emerging later in the nestling period. Results showed that nestlings have four distinct call types, two present at hatching, and two emerging when the nestlings undergo large physical changes in the second week of life. While two of the call types developed gradually towards more adult-like structures, the other two did not and were apparently only used for communication in the nest. Second, we tested whether nestlings could be discriminated individually based on their calls. All four call types were individually discriminable from hatching until the end of the study, thus providing evidence for vocal signatures. While the function of vocal signatures cannot be ascertained from this study, kea breeding biology rules out explanations based on preventing misdirected parental care. We suggest that vocal signatures may be relevant to the division of parental resources in the nest. [ABSTRACT FROM AUTHOR]

Background/aims: From a dynamic systems perspective of infant development, several systems (eg sensorimotor, perceptual, and reasoning, among others, may self-organise and change behavioural responses over time following experience. These changes in infant behaviour are often measured through the achievement of age-adjusted developmental milestones. However, the majority of research guiding the understanding of typical infant developmental trajectories rarely depicts collaborations across more than one or two disciplines. The purpose of this case report was to describe an interprofessional research collaboration among researchers and clinicians in clinical and experimental psychology, occupational therapy, speech-language pathology, and physical therapy to establish methods and procedures that describe different developmental domains in infancy for a single participant. Methods: One infant who was typically developing was video and audio recorded during 60 minutes of free play at ages 8, 12, and 16 months. Four research labs scored the middle 20 minutes of recorded time for infant and caregiver utterances, touch and motor behaviours, play participation and performance, co-occupation, and caregiver sensitivity to infant affect. The combined data from the four labs captured and revealed a rich description of the infant's development from 8 to 16 months of age. Results: The data for this single infant indicated that important developmental changes occurred leading to greater independence in communication, mobility and co-occupation, while reducing some of the requirements for attention from the caregiver. Conclusions: The procedures used within research labs by principal investigators from four disciplines to describe development in a single infant between 8 and 16 months of age yielded a rich example of development, consistent with published milestones. Future studies with larger sample sizes using the interdisciplinary research methods applied in this case study may improve the understanding of, influences on, and relationships between, infant developmental trajectories. [ABSTRACT FROM AUTHOR]

The Early Communication Indicator (ECI) was designed to measure expressive communication progress in young children. We evaluated using the 6-min ECI procedure for a new purpose-a sampling context for stable measures of vocal development of young children with autism spectrum disorder (ASD). We evaluated how many ECI sessions were required to adequately stabilize estimates of volubility, communicative use, and phonological complexity of vocalizations at two periods (average of 10 months apart). Participants included 83 young children with ASD (M age = 23.33 months). At study initiation, two phonological complexity variables required two sessions; other variables required three. At study endpoint, all variables required fewer sessions. Findings support the feasibility and stability of using the ECI for the new purpose. [ABSTRACT FROM AUTHOR]

At the earliest break of ancient hominins from their primate relatives in vocal communication, we propose a selection pressure on vocal fitness signaling by hominin infants. Exploratory vocalizations, not tied to expression of distress or immediate need, could have helped persuade parents of the wellness and viability of the infants who produced them. We hypothesize that hominin parents invested more in infants who produced such signals of fitness plentifully, neglecting or abandoning them less often than infants who produced the sounds less frequently. Selection for such exploratory vocalization provided a critically important inclination and capability relevant to language, we reason, because the system that encouraged spontaneous vocalization also made vocalization functionally flexible to an extent that has not been observed in any other animal. Although this vocal flexibility did not by itself create language, it provided an essential foundation upon which language would evolve through a variety of additional steps. In evaluating this speculation, we consider presumable barriers to evolving language that are thought to be implications of Darwinian Theory. It has been claimed that communication always involves sender self-interest and that self-interest leads to deceit, which is countered through clever detection by receivers. The constant battle of senders and receivers has been thought to pose an insuperable challenge to honest communication, which has been viewed as a requirement of language. To make communication honest, it has been proposed that stable signaling requires costly handicaps for the sender, and since language cannot entail high cost, the reasoning has suggested an insurmountable obstacle to the evolution of language. We think this presumed honesty barrier is an illusion that can be revealed by recognition of the fact that language is not inherently honest and in light of the distinction between illocutionary force and semantics. Our paper also considers barriers to the evolution of language (not having to do with honesty) that we think may have actually played important roles in preventing species other than humans from evolving language.

At the earliest break of ancient hominins from their primate relatives in vocal communication, we propose a selection pressure on vocal fitness signaling by hominin infants. Exploratory vocalizations, not tied to expression of distress or immediate need, could have helped persuade parents of the wellness and viability of the infants who produced them. We hypothesize that hominin parents invested more in infants who produced such signals of fitness plentifully, neglecting or abandoning them less often than infants who produced the sounds less frequently. Selection for such exploratory vocalization provided a critically important inclination and capability relevant to language, we reason, because the system that encouraged spontaneous vocalization also made vocalization functionally flexible to an extent that has not been observed in any other animal. Although this vocal flexibility did not by itself create language, it provided an essential foundation upon which language would evolve through a variety of additional steps. In evaluating this speculation, we consider presumable barriers to evolving language that are thought to be implications of Darwinian Theory. It has been claimed that communication always involves sender self-interest and that self-interest leads to deceit, which is countered through clever detection by receivers. The constant battle of senders and receivers has been thought to pose an insuperable challenge to honest communication, which has been viewed as a requirement of language. To make communication honest, it has been proposed that stable signaling requires costly handicaps for the sender, and since language cannot entail high cost, the reasoning has suggested an insurmountable obstacle to the evolution of language. We think this presumed honesty barrier is an illusion that can be revealed by recognition of the fact that language is not inherently honest and in light of the distinction between illocutionary force and semantics. Our paper also considers barriers to the evolution of language (not having to do with honesty) that we think may have actually played important roles in preventing species other than humans from evolving language. [ABSTRACT FROM AUTHOR]

Vocal development of cranes (Gruidae) has attracted scientific interest due to its special stage, voice breaking. During voice breaking, chicks of different crane species produce calls with two fundamental frequencies that correspond to those in adult low-frequency and juvenile high-frequency vocalizations. However, triggers that affect voice breaking in cranes are mainly unknown. Here we studied the voice breaking in the Siberian Crane (Leucogeranus leucogeranus) and test its relation to the body mass and testosterone level. We analyzed 5846 calls, 39 body mass measurements and 60 blood samples from 11 Siberian Crane chicks in 8 ages from 2.5 to 18 months of life together with 90 body mass measurements and 61 blood samples from 24 Siberian Crane adults. The individual duration of voice breaking and dates of its onset, culmination and completion depended neither on the body mass nor on the testosterone level at various ages. But we found correlation between the testosterone level and mean deltas of percentages of the high and low frequency components in Siberian Crane calls between the closest recording sessions. We also observed some coincidence in time between the mean dates of voice breaking onset and the termination of body mass gain (at 7.5 months of age), and between the mean dates of voice breaking completion and the start of a new breeding season. Similar relations have been shown previously for some other crane species. We also showed for the first time that the mean dates of voice breaking culmination correlated with the significant increase of the testosterone level (at 10.5 months of age). So, we suggest that voice breaking in cranes may be triggered by the end of chicks' body growth, is stimulated by the increase of testosterone level and ends soon after adult cranes stop taking care of their chicks. [ABSTRACT FROM AUTHOR]

Humans and songbirds face a common challenge: acquiring the complex vocal repertoire of their social group. Although humans are thought to be unique in their ability to convey symbolic meaning through speech, speech and birdsong are comparable in their acoustic complexity and the mastery with which the vocalizations of adults are acquired by young individuals. In this review, we focus on recent advances in the study of vocal development in humans and songbirds that shed new light on the emergence of distinct structural levels of vocal behavior and point to new possible parallels between both groups. [ABSTRACT FROM AUTHOR]

Active guidance of vocal learning by conspecifics has recently been found in several species, including some cetaceans and primates. However, in the zebra finch, Taeniopygia guttata , a commonly studied songbird, vocal learning was traditionally considered the product of memorization and imitation of a song model. Only recently have specific social feedback cues been shown to enhance song learning. What mechanisms drive the superior learning associated with social interactions? We recently found that 'fluff-ups', a nonvocal female arousal cue, facilitated song learning when played over video contingently on juvenile song production throughout development. However, it is unknown whether adults naturally respond in a contingent fashion to immature song, and whether young finches incorporate naturally occurring feedback into song learning. To investigate whether social influences affect song learning, the present study addressed the nature and significance of maternal and paternal cues associated with song development. We recorded unmanipulated zebra finch families throughout juvenile development and analysed their social interactions. We found that behaviours of both parents were associated with offspring song outcomes. Juvenile song learning could be predicted by the amount of contingent 'fluff-up' behaviours they received from their mothers throughout development. Fathers often sang immediately after a juvenile had sung, and paternal singing after juvenile singing was positively correlated with more accurate song learning in their sons. Conversely, when fathers sang before the juvenile sang, juveniles learned song less accurately. Our data suggest that parental vocal and gestural feedback plays a reinforcing role for song learning in zebra finches. There are many nonavian species, including chiropterans, pachyderms and pinnipeds, that modify their vocalizations in different developmental or social contexts but whose mechanisms of vocal learning are not known. Our findings suggest that these species should be closely examined for adult sensitivity to immature vocalizations and developmental capacity to learn from social feedback. • Social interaction enhances song learning in some birds, but mechanisms are unknown. • Zebra finch parents naturally display contingent responses to juvenile plastic song. • Song learning significantly correlated with contingent maternal 'fluff-ups'. • Juvenile song accuracy positively correlated with contingent paternal song. • Parental gestural and vocal feedback may reinforce song learning. [ABSTRACT FROM AUTHOR]

There has been only one published study of beluga vocal development, despite the value of ontognetic research for our understanding of sound-centered species. Findings from this seminal study were vital to understanding the beluga vocal repertoire, but further empirical study is necessary to determine if other calves follow similar trajectories in sound acquisition and development. Herein, we compare the two-year vocal progression of an additional calf, "Kylu," to the previous research. Additionally, we report on changes in acoustic energy distribution and source level of early calf sounds for the first time as part of a larger effort to understand the impacts of underwater noise on neonate vocalizations. From his day of birth, Kylu produced broadband pulse trains with upper- frequency limits above the study's Nyquist cutoff (128 kHz)--higher than what was reported by the previous study, which was limited by lower sampling rates. Pulsed signals were his most common sound type during his first year as in the previous study. Over Kylu's first month of life, pulse repetition rate, source level, and third quartile frequencies of the calf's pulse trains increased sig- nificantly. First and third quartile, center, and peak frequencies increased significantly over the first year as did pulse repetition rate and call duration. Mixed calls and tonal sounds were infrequent and not regularly produced until later in the first year of life. Calf acquisition of adult-like mixed call production appeared similarly between studies, while tonal acquisition appeared more variable. Kylu developed a contact call that was most similar to his mother's as found in the previous study, although slight variation in contact call acquisition was evident. By comparing beluga calves and employing new technology, we reveal species-specific parallels in development and provide new information about beluga calves. [ABSTRACT FROM AUTHOR]

For vocal communicators like humans and songbirds, survival and reproduction depend on highly developed auditory processing systems that can detect and differentiate nuanced differences in vocalizations, even amid noisy environments. Early auditory experience is critical to the development of these systems. In zebra finches and other songbirds, there is a sensitive period when young birds memorize a song that will serve as a model for their own vocal production. In addition to learning a specific tutor's song, the auditory system may also undergo critical developmental processes that support auditory perception of vocalizations more generally. Here, we investigate changes in intrinsic spiking dynamics among neurons in the caudal mesopallium, a cortical-level auditory area implicated in discriminating and learning species-specific vocalizations. A subset of neurons in this area only fire transiently at the onset of current injections (i.e., phasic firing), a dynamical property that can enhance the reliability and selectivity of neural responses to complex acoustic stimuli. At the beginning of the sensitive period, just after zebra finches have fledged from the nest, there is an increase in the proportion of caudal mesopallium neurons with phasic excitability, and in the proportion of neurons expressing Kvl.l, a low-threshold channel that facilitates phasic firing. This plasticity requires exposure to a complex, noisy environment and is greater in males, the only sex that sings in this species. This shift to more phasic dynamics is therefore an experience-dependent adaptation that could facilitate auditory processing in noisy, acoustically complex conditions during a key stage of vocal development. [ABSTRACT FROM AUTHOR]

Temporal coordination of vocal exchanges between mothers and their infants emerges from a developmental process that relies on the ability of communication partners to co-coordinate and predict each other’s turns. Consequently, the partners engage in communicative niche construction that forms a foundation for language in human infancy. While robust universals in vocal turn-taking have been found, differences in the timing of maternal and infant vocalizations have also been reported across cultures. In this study, we examine the temporal structure of vocal interactions in 38 mother–infant dyads in the first two years across two cultures—American and Lebanese—by studying observed and randomized distributions of vocalizations, focusing on both gaps and overlaps in naturalistic 10-min vocal interactions. We conducted a series of simulations using Kolmogorov–Smirnov (K–S) tests to examine whether the observed responsivity patterns differed from randomly generated simulations of responsivity patterns in both Arabic and English for mothers responding to infants and for infants responding to mothers. Results revealed that both mothers and infants engaged in conversational alternation, with mothers acting similarly across cultures. By contrast, significant differences were observed in the timing of infant responses to maternal utterances, with the Lebanese infants’ tendency to cluster their responses in the first half-second after the offset of the Lebanese mothers’ utterances to a greater extent than their American counterparts. We speculate that the results may be due to potential phonotactic differences between Arabic and English and/or to differing child-rearing practices across Lebanese and American cultures. The findings may have implications for early identification of developmental disorders such as autism spectrum disorders within and across cultures.

Temporal coordination of vocal exchanges between mothers and their infants emerges from a developmental process that relies on the ability of communication partners to co-coordinate and predict each other's turns. Consequently, the partners engage in communicative niche construction that forms a foundation for language in human infancy. While robust universals in vocal turn-taking have been found, differences in the timing of maternal and infant vocalizations have also been reported across cultures. In this study, we examine the temporal structure of vocal interactions in 38 mother–infant dyads in the first two years across two cultures—American and Lebanese—by studying observed and randomized distributions of vocalizations, focusing on both gaps and overlaps in naturalistic 10-min vocal interactions. We conducted a series of simulations using Kolmogorov–Smirnov (K–S) tests to examine whether the observed responsivity patterns differed from randomly generated simulations of responsivity patterns in both Arabic and English for mothers responding to infants and for infants responding to mothers. Results revealed that both mothers and infants engaged in conversational alternation, with mothers acting similarly across cultures. By contrast, significant differences were observed in the timing of infant responses to maternal utterances, with the Lebanese infants' tendency to cluster their responses in the first half-second after the offset of the Lebanese mothers' utterances to a greater extent than their American counterparts. We speculate that the results may be due to potential phonotactic differences between Arabic and English and/or to differing child-rearing practices across Lebanese and American cultures. The findings may have implications for early identification of developmental disorders such as autism spectrum disorders within and across cultures. [ABSTRACT FROM AUTHOR]

Young birds communicate their need to parents through complex begging displays that include visual and acoustic cues. Nestlings of interspecific brood parasites must 'tune' into these communication channels to secure parental care from their hosts. Various studies show that parasitic nestlings can effectively manipulate host parental behaviour through their begging calls, but how these manipulative acoustic signals develop in growing parasites remains poorly understood. We investigated the influence of social experience on begging call development in a host‐specialist brood parasite, the Screaming Cowbird Molothrus rufoaxillaris. Screaming Cowbird nestlings look and sound similar to those of the primary host, the Greyish Baywing Agelaioides badius. This resemblance is likely to be adaptive because Baywings discriminate against fledglings unlike their own and provision nests at higher rates in response to Baywing‐like begging calls than to non‐mimetic begging calls. By means of cross‐fostering and playback experiments, we tested whether the acoustic cues that elicit recognition by Baywings develop innately in Screaming Cowbird nestlings or are acquired through social experience with host parents or nest mates. Our results suggest that begging call structure was partially modulated by experience because Baywing‐reared Screaming Cowbird and host nestlings were acoustically more similar as age increased, whereas acoustic similarity between cross‐fostered and Baywing‐reared Screaming Cowbird nestlings decreased from 4–5 to 8–10 days of age. Cross‐fostered Screaming Cowbirds developed begging calls of lower minimum frequency and broader bandwidth than those of Baywing‐reared Screaming Cowbirds by the age of 8–10 days. Despite the observed differences in begging call structure, however, adult Baywings responded similarly to begging calls of 8‐ to 10‐day‐old cross‐fostered and Baywing‐reared Screaming Cowbirds, suggesting that these were functionally equivalent from the host's perspective. These findings support the idea that, although rearing environment can influence certain begging call parameters, the acoustic cues that serve for offspring recognition by Baywings develop in young Screaming Cowbirds independently of social experience. [ABSTRACT FROM AUTHOR]

Bats are an appealing animal for investigating the biological basis and evolution of speech-related traits in wild mammal systems. We investigated vocal development in Horsfield's leaf-nosed bat pups, Hipposideros larvatus. We found that newborn bats emit many types of isolation calls, including downward frequency modulation (DFM), arched frequency modulation (AFM), upward frequency modulation (UFM), and others. The gradual decrease of Euclidean distance measurements revealed that pup isolation calls (DFM, AFM, UFM) gradually change into adult social calls. Furthermore, one of the isolation call types (UFM type) encoded an individual signature. By contrast, we report that early echolocation calls and isolation calls develop in parallel. As pups develop, early echolocation calls gradually mature and transform into adult-like echolocation calls. The interval and duration of echolocation calls decreases, while the peak frequency and bandwidth of frequency modulation increases. [ABSTRACT FROM AUTHOR]

Investigating nonhuman primate vocal communication is often with the intention of elucidating their similarities with human speech and thus reconstructing the evolutionary history of this important behaviour. However, putative parallels between primate and human vocal behaviours have, in some respects, remained elusive. Here, we review two lines of research in marmoset monkeys on volitional vocal control and vocal learning during development that could bridge our understanding of the relationship between primate vocalizations and human speech. Regarding volitional control, we review how changes in vocal output are not solely due to changes in arousal levels and their effect on the vocal apparatus; extrinsic factors like the vocalizations from other conspecifics also have an important influence. With regard to vocal learning, we describe not only how infant marmoset vocalizations undergo dramatic acoustic changes during development that are not wholly explained by physical growth, but also how, as in humans, contingent vocal responses from parents influence the rate of vocal development. We argue that the similarities in the vocal systems of marmoset monkeys and humans may be due to their shared cooperative breeding strategy and prosociality. • Volitional control and vocal learning are essential speech elements. • Marmoset monkey vocal control trades arousal with conspecific signals. • Infant marmoset monkeys exhibit production-related vocal learning. • Human and marmoset communication are linked to cooperative breeding strategies. [ABSTRACT FROM AUTHOR]

Puppyhood is a very active social and vocal period in a harbor seal's life Phoca vitulina. An important feature of vocalizations is their temporal and rhythmic structure, and understanding vocal timing and rhythms in harbor seals is critical to a cross-species hypothesis in evolutionary neuroscience that links vocal learning, rhythm perception, and synchronization. This study utilized analytical techniques that may best capture rhythmic structure in pup vocalizations with the goal of examining whether (1) harbor seal pups show rhythmic structure in their calls and (2) rhythms evolve over time. Calls of 3 wild-born seal pups were recorded daily over the course of 1–3 weeks; 3 temporal features were analyzed using 3 complementary techniques. We identified temporal and rhythmic structure in pup calls across different time windows. The calls of harbor seal pups exhibit some degree of temporal and rhythmic organization, which evolves over puppyhood and resembles that of other species' interactive communication. We suggest next steps for investigating call structure in harbor seal pups and propose comparative hypotheses to test in other pinniped species. [ABSTRACT FROM AUTHOR]