Types Of Vocalizations Research Articles

Bottlenose dolphin predation on flathead grey mullets using barrier feeding techniques: a visual and acoustic case study in the Mediterranean Sea

We report first-time evidence of barrier feeding techniques in the population of common bottlenose dolphin (Tursiops truncatus) at the estuary of the Tiber River (Rome, Italy), used to prey on the flathead grey mullet (Mugil cephalus). We describe an event that occurred in summer 2023, consisting of dolphins forcing schools of mullets against different types of barriers, i.e. sea surface, coastal breakwater blocks and other dolphins. We provide the first visual and acoustic account of this predation modality in the Mediterranean Sea, showing that bottlenose dolphins adopted techniques to fragmentate prey assemblages and then to limit prey escape routes by forcing them against barriers. In this way dolphins were able to catch the mullets both in air and in the water. Such a technique possibly depends on the ability of sensing each other in the hunting group and of exchanging information through different types of vocalizations.

Appreciation of singing and speaking voices is highly idiosyncratic.

Voice preferences are an integral part of interpersonal interactions and shape how people connect with each other. While a large number of studies have investigated the mechanisms behind (speaking) voice attractiveness, very little research was dedicated to other types of vocalizations. In this Registered Report, we proposed to investigate voice preferences with an integrative approach. To this end, we used a newly recorded and validated stimulus set of contrasting vocalizations by 22 highly trained female singers speaking and singing the same material (in Brazilian Portuguese) in contrasting styles (sung as a lullaby, as a pop song or as an opera aria; and spoken aloud as if directed to an adult audience and as if directed to an infant). We asked 62 participants to rate these vocalizations in terms of how much they liked them; and we compared the amount of shared taste (that is, how much participants agreed in their preferences) across styles. We found highly idiosyncratic preferences across all styles. Our predictions concerning shared taste were not confirmed: although shared taste was higher for lullaby than for pop singing, it was unexpectedly higher for operatic than pop singing, and higher for infant-directed than adult-directed speech. Conversely, our prediction of limited consistency in average preferences for some singers across styles was confirmed, contradicting sexual selection-based ideas of singing and speaking as 'backup' signals of individual fitness. Our findings draw attention to the role of individual differences in voice preferences and highlight the need for a broader approach to understanding the underlying mechanisms of voice preferences. Stage 1 recommendation and review history: https://rr.peercommunityin.org/articles/rec?id=357. Stage 2 recommendation and review history: https://rr.peercommunityin.org/articles/rec?id=802.

Acoustic features of vocalizations in typically developing and autistic infants in the first year

We describe acoustic patterns across the five most prominent vocal types in typically developing infants (TD) and compare them with patterns in infants who develop autism (ASD) or a developmental disability (DD) not related to autism. Infant-directed speech (IDS) is a potentially important influence on such vocal acoustic patterns. Both acoustic patterns and effects of IDS are important for understanding the earliest origins of communication disorders. To compare duration, pitch and loudness of infant vocalizations for three groups of infants (TD, ASD, DD) in circumstances with high or low amounts of IDS. Two five-minute segments from each of 1259 all-day recordings across the first year were coded and acoustically analyzed for three groups of infants (130 TD, 44 ASD, 21 DD). Duration, mean fundamental frequency, and root mean square amplitude were determined for >162,000 infant utterances. Cries were longest and loudest, and vowel-like sounds were shortest of the five vocal types in all groups. TD infants showed significant alterations in vocal acoustics during periods of high IDS. Strong similarities in acoustic patterns occurred across the three groups, but only the TD group showed significant acoustic effects of IDS.

Voices without words: the spectrum of nonverbal vocalisations

ABSTRACT Nonverbal vocalisations are a fundamental part of human life. Here, we use Tinbergen’s ethological framework to examine the functions, ontogenetic trajectories, evolutionary history, and underlying mechanisms of five types of vocalisations: cries, laughter, moans, screams, and sighs. Integrating insights from evolutionary biology and social psychology, we demonstrate how biological functions and social factors shape vocalisations. Tracing the development of vocalisations from infancy to adulthood emphasises the role of innate tendencies, as well as delineating processes of social learning. For each vocalisation type, we map their distinct nature and communicative potential: cries are crucial for survival and caregiving responses; laughter fosters social bonding and group cohesion; moans convey a wide range of internal states from pleasure to discomfort; screams serve as urgent alarms in critical situations; and sighs regulate emotions and signal shifts in emotional states. We conclude that both biological and social factors must be considered to understand nonverbal vocalisations.

Broiler chicken vocalization analysis during a medium-scale heat stress experiment

The poultry industry in Flanders, Belgium, is characterized by highly efficient production mechanisms. To improve awareness for animal health and welfare, the use of neural network-based broiler vocalization detectors has been recently proposed in scientific literature. However, these tools have not yet been tested when used continuously in large-scale deployments. This paper describes the deployment of the broiler vocalization detector to analyze the sonic environment during four experimental rounds, each containing 560 broilers, in a medium scale housing at ILVO, Belgium. Half the broilers were subjected to periods of heat stress (ambient temperature increased to 32°C for 6h/day for 10 days during the last weeks of their lives) and the effect on the diurnal broiler vocalization pattern and occurrence of warbles, pleasure notes, short beeps and distress calls is discussed. While these four different types of vocalizations are common vocalizations in young birds, new types of vocalizations are emerging at an older age. A clustering has been performed to further analyze these new types of vocalizations occurring.

Vocal usage learning and vocal comprehension learning in harbor seals

BackgroundWhich mammals show vocal learning abilities, e.g., can learn new sounds, or learn to use sounds in new contexts? Vocal usage and comprehension learning are submodules of vocal learning. Specifically, vocal usage learning is the ability to learn to use a vocalization in a new context; vocal comprehension learning is the ability to comprehend a vocalization in a new context. Among mammals, harbor seals (Phoca vitulina) are good candidates to investigate vocal learning. Here, we test whether harbor seals are capable of vocal usage and comprehension learning.ResultsWe trained two harbor seals to (i) switch contexts from a visual to an auditory cue. In particular, the seals first produced two vocalization types in response to two hand signs; they then transitioned to producing these two vocalization types upon the presentation of two distinct sets of playbacks of their own vocalizations. We then (ii) exposed the seals to a combination of trained and novel vocalization stimuli. In a final experiment, (iii) we broadcasted only novel vocalizations of the two vocalization types to test whether seals could generalize from the trained set of stimuli to only novel items of a given vocal category. Both seals learned all tasks and took ≤ 16 sessions to succeed across all experiments. In particular, the seals showed contextual learning through switching the context from former visual to novel auditory cues, vocal matching and generalization. Finally, by responding to the played-back vocalizations with distinct vocalizations, the animals showed vocal comprehension learning.ConclusionsIt has been suggested that harbor seals are vocal learners; however, to date, these observations had not been confirmed in controlled experiments. Here, through three experiments, we could show that harbor seals are capable of both vocal usage and comprehension learning.

Vocal-visual combinations in wild chimpanzees

Living organisms throughout the animal kingdom habitually communicate with multi-modal signals that use multiple sensory channels. Such composite signals vary in their communicative function, as well as the extent to which they are recombined freely. Humans typically display complex forms of multi-modal communication, yet the evolution of this capacity remains unknown. One of our two closest living relatives, chimpanzees, also produce multi-modal combinations and therefore may offer a valuable window into the evolutionary roots of human communication. However, a currently neglected step in describing multi-modal systems is to disentangle non-random combinations from those that occur simply by chance. Here we aimed to provide a systematic quantification of communicative behaviour in our closest living relatives, describing non-random combinations produced across auditory and visual modalities. Through recording the behaviour of wild chimpanzees from the Kibale forest, Uganda we generated the first repertoire of non-random combined vocal and visual components. Using collocation analysis, we identified more than 100 vocal-visual combinations which occurred more frequently than expected by chance. We also probed how multi-modal production varied in the population, finding no differences in the number of visual components produced with vocalisations as a function of age, sex or rank. As expected, chimpanzees produced more visual components alongside vocalizations during longer vocalization bouts, however, this was only the case for some vocalization types, not others. We demonstrate that chimpanzees produce a vast array of combined vocal and visual components, exhibiting a hitherto underappreciated level of multi-modal complexity.

Acoustic sensors to detect the rate of cow vocalization in a complex farm environment

Acoustic technologies provide a method to investigate cow vocalization. This study demonstrated that collar attached acoustic sensors can determine vocalization from continuous acoustic recordings of cows under grazing conditions. In this study a total of 4843 vocalizations from 10 cows were observed over 3 days. Algorithms were developed to differentiate cow vocalization from other farm noises and the F1-statistic for the vocalization classification model was 95 % for the test dataset. Models for the rate of vocalization per cow (R2 = 0.99), average vocalization duration per cow (R2 = 0.83), and the coefficient of variation (CV) of duration of vocalization per cow (R2 = 0.73) in the validation dataset demonstrate that it is feasible to determine vocalization traits that provide information on the state of the animal. There was also significant between-cow variation in the vocalization traits examined in this study, with a rate of vocalization per cow that ranged from 20 to 584 events day−1, an average duration of vocalization per cow that ranged from 1.0 to 1.4 s, a CV of duration of vocalization per cow that ranged from 0.28 to 0.42. The transition probabilities between vocalization type (closed, mixed, open mouth) were also calculated for each cow and there was a 1.3–14-fold between-cow variation in the transition probabilities. The total number of vocalizations per hour interval was highly variable and ranged from zero to 250 vocalizations, depending on cow and time of day. The cows largely vocalized at similar times of the day, although we demonstrated that the technology could identify cows that differ in their pattern of vocalization relative to the herd and relative to their vocalization patterns on previous days. These models can be used to investigate the role of management and environmental factors on cow vocalization, and to develop technologies that respond to cow vocalization behaviour.

Effect of Vocalization on Human Aerosol Dynamics: Whispering Produces More Aerosols than Speaking

ObjectivesSound pressure and exhaled flow have been identified as important factors associated with higher particle emissions. The aim of this study was to assess how different vocalizations affect the particle generation independently from other factors. DesignExperimental study MethodsThirty-three experienced singers repeated two different sentences in normal loudness and whispering. The first sentence consisted mainly of consonants like /k/ and /t/ as well as open vowels, while the second sentence also included the /s/ sound and contained primarily closed vowels. The particle emission was measured using condensation particle counter (CPC, 3775 TSI Inc.) and aerodynamic particle sizer (APS, 3321 TSI Inc.). The CPC measured particle number concentration for particles larger than 4 nm and mainly reflects the number of particles smaller than 0.5 µm since these particles dominate total number concentration. The APS measured particle size distribution and number concentration in the size range of 0.5 – 10 µm and data were divided into > 1 µm and < 1 µm particle size ranges. Generalized linear mixed effects models were constructed to assess the factors affecting particle generation. ResultsWhispering produced more particles than speaking and sentence 1 produced more particles than sentence 2 while speaking. Sound pressure level had effect on particle production independently from vocalization. The effect of exhaled airflow was not statistically significant. ConclusionsBased on our results the type of vocalization has a significant effect on particle production independently from other factors such as sound pressure level.

Gekko gecko as a model organism for understanding aspects of laryngeal vocal evolution.

The ability to communicate through vocalization plays a key role in the survival of animals across all vertebrate groups. Although avian reptiles have received much attention relating to their stunning sound repertoire, non-avian reptiles have been wrongfully assumed to have less elaborate vocalization types, and little is known about the biomechanics of sound production and their underlying neural pathways in this group. We investigated alarm calls of Gekko gecko using audio and cineradiographic recordings. Acoustic analysis revealed three distinct call types: a sinusoidal call type (type 1); a train-like call type, characterized by distinct pulse trains (type 3); and an intermediate type, which showed both sinusoidal and pulse train components (type 2). Kinematic analysis of cineradiographic recordings showed that laryngeal movements differ significantly between respiratory and vocal behavior. During respiration, animals repeatedly moved their jaws to partially open their mouths, which was accompanied by small glottal movements. During vocalization, the glottis was pulled back, contrasting with what has previously been reported. In vitro retrograde tracing of the nerve innervating the laryngeal constrictor and dilator muscles revealed round to fusiform motoneurons in the hindbrain-spinal cord transition ipsilateral to the labeled nerve. Taken together, our observations provide insight into the alarm calls generated by G. gecko, the biomechanics of this sound generation and the underlying organization of motoneurons involved in the generation of vocalizations. Our observations suggest that G. gecko may be an excellent non-avian reptile model organism for enhancing our understanding of the evolution of vertebrate vocalization.

The breath shape controls intonation of mouse vocalizations.

Intonation in speech is the control of vocal pitch to layer expressive meaning to communication, like increasing pitch to indicate a question. Also, stereotyped patterns of pitch are used to create distinct sounds with different denotations, like in tonal languages and, perhaps, the 10 sounds in the murine lexicon. A basic tone is created by exhalation through a constricted laryngeal voice box, and it is thought that more complex utterances are produced solely by dynamic changes in laryngeal tension. But perhaps, the shifting pitch also results from altering the swiftness of exhalation. Consistent with the latter model, we describe that intonation in most vocalization types follows deviations in exhalation that appear to be generated by the re-activation of the cardinal breathing muscle for inspiration. We also show that the brainstem vocalization central pattern generator, the iRO, can create this breath pattern. Consequently, ectopic activation of the iRO not only induces phonation, but also the pitch patterns that compose most of the vocalizations in the murine lexicon. These results reveal a novel brainstem mechanism for intonation.

Vocal repertoire and individuality in the plains zebra (Equus quagga).

Acoustic signals are vital in animal communication, and quantifying them is fundamental for understanding animal behaviour and ecology. Vocalizations can be classified into acoustically and functionally or contextually distinct categories, but establishing these categories can be challenging. Newly developed methods, such as machine learning, can provide solutions for classification tasks. The plains zebra is known for its loud and specific vocalizations, yet limited knowledge exists on the structure and information content of its vocalzations. In this study, we employed both feature-based and spectrogram-based algorithms, incorporating supervised and unsupervised machine learning methods to enhance robustness in categorizing zebra vocalization types. Additionally, we implemented a permuted discriminant function analysis to examine the individual identity information contained in the identified vocalization types. The findings revealed at least four distinct vocalization types-the 'snort', the 'soft snort', the 'squeal' and the 'quagga quagga'-with individual differences observed mostly in snorts, and to a lesser extent in squeals. Analyses based on acoustic features outperformed those based on spectrograms, but each excelled in characterizing different vocalization types. We thus recommend the combined use of these two approaches. This study offers valuable insights into plains zebra vocalization, with implications for future comprehensive explorations in animal communication.

Adult Verbal Responses Facilitating Child Vocalizations

Objectives: This study aimed to investigate whether adults in the vicinity of children respond differently to various child vocalization types within three-event sequences of “child vocalization-adult verbal response-child vocalization” occurring in everyday life. Additionally, this study examined the types of adult verbal responses that facilitate child vocalizations within the series of three-event sequential interactions between children and adults. Methods: Data was collected using the LENA (Language ENvironment Analysis) from 30 children aged 12 to 18 months and their families. Three-event sequences of interactions between children and adults were selected from twenty 5-minute recorded segments with the highest conversational turn counts. Child vocalizations before and after adult verbal responses were broadly classified into canonical babblings and non-canonical babblings, and then coded into subcategories for each babbling type. Adult verbal responses were classified into different pragmatic types. Results: Adults responded differently depending on children’s non-canonical and canonical babblings. Among pragmatic types of adult verbal responses, imitation, recast, and expansion were prominently observed following canonical babblings with more than two syllables. Adult verbal responses such as acknowledgment and recast facilitated children in producing more advanced vocalization forms. Conclusion: This study supports bi-directional relationships in interactions between children and adults and provides insights into which child-adult vocal exchanges facilitate child vocalizations and early speech-language development.

Isochrony as ancestral condition to call and song in a primate.

Animal songs differ from calls in function and structure, and have comparative and translational value, showing similarities to human music. Rhythm in music is often distributed in quantized classes of intervals known as rhythmic categories. These classes have been found in the songs of a few nonhuman species but never in their calls. Are rhythmic categories song-specific, as in human music, or can they transcend the song-call boundary? We analyze the vocal displays of one of the few mammals producing both songs and call sequences: Indri indri. We test whether rhythmic categories (a) are conserved across songs produced in different contexts, (b) exist in call sequences, and (c) differ between songs and call sequences. We show that rhythmic categories occur across vocal displays. Vocalization type and function modulate deployment of categories. We find isochrony (1:1 ratio, like the rhythm of a ticking clock) in all song types, but only advertisement songs show three rhythmic categories (1:1, 1:2, 2:1 ratios). Like songs, some call types are also isochronous. Isochrony is the backbone of most indri vocalizations, unlike human speech, where it is rare. In indri, isochrony underlies both songs and hierarchy-less call sequences and might be ancestral to both.

To Study the Different Types of Vocalizations in Domestic Cats (Felis catus)

To Study the Different Types of Vocalizations in Domestic Cats (Felis catus)

Infant vocal category exploration as a foundation for speech development.

Non-random exploration of infant speech-like vocalizations (e.g., squeals, growls, and vowel-like sounds or "vocants") is pivotal in speech development. This type of vocal exploration, often noticed when infants produce particular vocal types in clusters, serves two crucial purposes: it establishes a foundation for speech because speech requires formation of new vocal categories, and it serves as a basis for vocal signaling of wellness and interaction with caregivers. Despite the significance of clustering, existing research has largely relied on subjective descriptions and anecdotal observations regarding early vocal category formation. In this study, we aim to address this gap by presenting the first large-scale empirical evidence of vocal category exploration and clustering throughout the first year of life. We observed infant vocalizations longitudinally using all-day home recordings from 130 typically developing infants across the entire first year of life. To identify clustering patterns, we conducted Fisher's exact tests to compare the occurrence of squeals versus vocants, as well as growls versus vocants. We found that across the first year, infants demonstrated clear clustering patterns of squeals and growls, indicating that these categories were not randomly produced, but rather, it seemed, infants actively engaged in practice of these specific categories. The findings lend support to the concept of infants as manifesting active vocal exploration and category formation, a key foundation for vocal language.

Vocal complexity in the long calls of Bornean orangutans.

Vocal complexity is central to many evolutionary hypotheses about animal communication. Yet, quantifying and comparing complexity remains a challenge, particularly when vocal types are highly graded. Male Bornean orangutans (Pongo pygmaeus wurmbii) produce complex and variable "long call" vocalizations comprising multiple sound types that vary within and among individuals. Previous studies described six distinct call (or pulse) types within these complex vocalizations, but none quantified their discreteness or the ability of human observers to reliably classify them. We studied the long calls of 13 individuals to: (1) evaluate and quantify the reliability of audio-visual classification by three well-trained observers, (2) distinguish among call types using supervised classification and unsupervised clustering, and (3) compare the performance of different feature sets. Using 46 acoustic features, we used machine learning (i.e., support vector machines, affinity propagation, and fuzzy c-means) to identify call types and assess their discreteness. We additionally used Uniform Manifold Approximation and Projection (UMAP) to visualize the separation of pulses using both extracted features and spectrogram representations. Supervised approaches showed low inter-observer reliability and poor classification accuracy, indicating that pulse types were not discrete. We propose an updated pulse classification approach that is highly reproducible across observers and exhibits strong classification accuracy using support vector machines. Although the low number of call types suggests long calls are fairly simple, the continuous gradation of sounds seems to greatly boost the complexity of this system. This work responds to calls for more quantitative research to define call types and quantify gradedness in animal vocal systems and highlights the need for a more comprehensive framework for studying vocal complexity vis-à-vis graded repertoires.

Gaze Orienting in the Social World: An Exploration of the Role Played by Caregiving Vocal and Tactile Behaviors in Infants with Visual Impairment and in Sighted Controls.

Infant attention is a cognitive function that underlines sensory-motor integration processes at the interface between the baby and the surrounding physical and socio-relational environment, mainly with the caregivers. The investigation of the role of non-visual inputs (i.e., vocal and tactile) provided by the caregivers in shaping infants' attention in the context of visual impairment is relevant from both a theoretical and clinical point of view. This study investigated the social attention (i.e., gaze orientation) skills in a group of visually impaired (VI) and age-matched sighted controls (SCs) between 9 and 12 months of age. Moreover, the role of VI severity and maternal vocalizations and touch in shaping the social attention were investigated. Overall, 45 infants and their mothers participated in a video-recorded 4 min interaction procedure, including a play and a still-face episode. The infants' gaze orientation (i.e., mother-directed, object-directed, or unfocused) and the types of maternal vocalizations and touch (i.e., socio-cognitive, affective) were micro-analytically coded. Maternal vocalizations and touch were found to influence gaze orientation differently in VI infants compared SCs. Moreover, the group comparisons during the play episode showed that controls were predominantly oriented to the mothers, while VI infants were less socially oriented. Visual impairment severity did not emerge as linked with social attention. These findings contribute to our understanding of socio-cognitive developmental trajectories in VI infants and highlight the need for tailored interventions to promote optimal outcomes for VI populations.

The Mouse Inferior Colliculus Responds Preferentially to Non-Ultrasonic Vocalizations.

The inferior colliculus (IC), the midbrain auditory integration center, analyzes information about social vocalizations and provides substrates for higher level processing of vocal signals. We used multichannel recordings to characterize and localize responses to social vocalizations and synthetic stimuli within the IC of female and male mice, both urethane anesthetized and unanesthetized. We compared responses to ultrasonic vocalizations (USVs) with other vocalizations in the mouse repertoire and related vocal responses to frequency tuning, IC subdivisions, and sex. Responses to lower frequency, broadband social vocalizations were widespread in IC, well represented throughout the tonotopic axis, across subdivisions, and in both sexes. Responses to USVs were much more limited. Although we observed some differences in tonal and vocal responses by sex and subdivision, representations of vocal responses by sex and subdivision were largely the same. For most units, responses to vocal signals occurred only when frequency response areas overlapped with spectra of the vocal signals. Since tuning to frequencies contained within the highest frequency USVs is limited (<15% of IC units), responses to these vocalizations are correspondingly limited (<5% of sound-responsive units). These results highlight a paradox of USV processing in some rodents: although USVs are the most abundant social vocalization, their representation and the representation of corresponding frequencies are less than lower frequency social vocalizations. We interpret this paradox in light of observations suggesting that USVs with lower frequency elements (<50 kHz) are associated with increased emotional intensity and engage a larger population of neurons in the mouse auditory system.

Isochrony in barks of Cape fur seal (Arctocephalus pusillus pusillus) pups and adults.

Animal vocal communication often relies on call sequences. The temporal patterns of such sequences can be adjusted to other callers, follow complex rhythmic structures or exhibit a metronome-like pattern (i.e., isochronous). How regular are the temporal patterns in animal signals, and what influences their precision? If present, are rhythms already there early in ontogeny? Here, we describe an exploratory study of Cape fur seal (Arctocephalus pusillus pusillus) barks-a vocalisation type produced across many pinniped species in rhythmic, percussive bouts. This study is the first quantitative description of barking in Cape fur seal pups. We analysed the rhythmic structures of spontaneous barking bouts of pups and adult females from the breeding colony in Cape Cross, Namibia. Barks of adult females exhibited isochrony, that is they were produced at fairly regular points in time. Instead, intervals between pup barks were more variable, that is skipping a bark in the isochronous series occasionally. In both age classes, beat precision, that is how well the barks followed a perfect template, was worse when barking at higher rates. Differences could be explained by physiological factors, such as respiration or arousal. Whether, and how, isochrony develops in this species remains an open question. This study provides evidence towards a rhythmic production of barks in Cape fur seal pups and lays the groundwork for future studies to investigate the development of rhythm using multidimensional metrics.