Nonhuman Vocalizations Research Articles

Humans' Ability to Assess Emotion in Dog Barks Only Slightly Affected by their Country of Residence, a Replication of Pongracz et al. (2005) in a Portuguese Sample

An original experiment by Pongrácz et al. (2005) showed that Hungarian listeners were able to categorize recordings of dog barks recorded in various contexts above chance level and assessed the barking dogs’ emotional state in accordance with these contexts. The present study sought to replicate this experiment in a Portuguese sample. Similar to Hungarians, Portuguese dog owners and non-owners rated the barks in accordance with their specific social contexts (e.g., a dog left alone is most probably in fearful state instead of a playful one), and correctly categorized territorial and separation barks above chance level. Similar error patterns were observed across subjects from the two countries. The Portuguese participants, however, were less successful in categorizing barks than the Hungarians. Additionally, results showed both sex and dog ownership effects. Women from both countries tended to attribute higher levels of despair to all bark recordings. Moreover, within the Portuguese sample, dog-owners were generally more accurate in categorizing the recordings than non-owners. Overall, the results of our replication study, besides supporting the universality of vocal emotion recognition in mammals, calls attention to the possibility of country/culture- and also individual-specific effects on human perception and understanding of nonhuman vocalizations.

Humans Discriminate Individual Zebra Finches by their Song

Comparative experiments have greatly advanced the field of biolinguistics in the 21st century, but so far very little research has focused on human perception of non-human animal vocalizations. Studies with zebra finch (Taeniopygia guttata) songs found that humans cannot perceive the full range of acoustic cues that zebra finches hear in their songs, although it remained unclear how much individual information is lost. Individual heterospecific discrimination by humans has only been shown with rhesus monkey (Macaca mulatta) voices. The present study examined whether human adults could discriminate two individual zebra finches by their songs, using a forced- choice Same-Different Paradigm. Results showed that adults can discriminate two individual zebra finches with high accuracy and without prior training. Discrimination mostly relied on differences in pitch contour, but discrimination was still possible with lower accuracy when pitch contour was removed. Future studies should expand these findings with more diverse non-human animal vocalizations.

The role of prosody in infants' preference for speech: A comparison between speech and birdsong.

Speech preferences emerge very early in infancy, pointing to a special status for speech in auditory processing and a crucial role of prosody in driving infant preferences. Recent theoretical models suggest that infant auditory perception may initially encompass a broad range of human and nonhuman vocalizations, then tune in to relevant sounds for the acquisition of species-specific communication sounds. However, little is known about sound properties eliciting infants' tuning-in to speech. To address this issue, we presented a group of 4-month-olds with segments of non-native speech (Mandarin Chinese) and birdsong, a nonhuman vocalization that shares some prosodic components with speech. A second group of infants was presented with the same segment of birdsong paired with Mandarin played in reverse. Infants showed an overall preference for birdsong over non-native speech. Moreover, infants in the Backward condition preferred birdsong over backward speech whereas infants in the Forward condition did not show clear preference. These results confirm the prominent role of prosody in early auditory processing and suggest that infants' preferences may privilege communicative vocalizations featured by certain prosodic dimensions regardless of the biological source of the sound, human or nonhuman.

A biosemiotic reading of Michel Onfray’sCosmos: Rethinking the essence of communication from an ecocentric and scientific perspective

AbstractInCosmos, Onfray argues in favor of a (re-) conceptualization of communication based on recent scientific discoveries. Similar to many researchers in the field of biosemiotics, the controversial philosopher posits that all life forms engage in constant semiosis. As opposed to being a singular characteristic that only homo sapiens possess, Onfray contends that all organisms are endowed with semiosic faculties that enable them to exchange information in purposeful and meaningful ways. Appealing to scientific logic, the philosopher debunks the common misconception that non-human vocalizations are merely the product of an internal machinery. Onfray offers concrete examples from both the animal and plant kingdom illustrating the astounding complexity of non-human semiosis. Nonetheless, in his reflections about the advent of hyperreality, the philosopher nuances his philosophical position by underscoring what makes the human primary modelling device of “language” the most sophisticated form of semiosis that exists in the biosphere. Although all material beings communicate with each other effectively in order to survive, to relate to each other, and to reproduce, Onfray recognizes that humans appear to have a heightened predisposition for symbolic exchange. The philosopher affirms that the human Umwelt is the richest and most complex semiotic space of all. Due to the pervasive nature of human semiosis in the modern world that threatens the ability of other life forms to create, stockpile, emit, and interpret signs, the philosopher also insists that preserving the fragile semiosic diversity of the “soundscape” is the key to averting the impending, anthropogenic eco-apocalypse.

Hierarchical temporal structure in music, speech and animal vocalizations: jazz is like a conversation, humpbacks sing like hermit thrushes

Humans talk, sing and play music. Some species of birds and whales sing long and complex songs. All these behaviours and sounds exhibit hierarchical structure-syllables and notes are positioned within words and musical phrases, words and motives in sentences and musical phrases, and so on. We developed a new method to measure and compare hierarchical temporal structures in speech, song and music. The method identifies temporal events as peaks in the sound amplitude envelope, and quantifies event clustering across a range of timescales using Allan factor (AF) variance. AF variances were analysed and compared for over 200 different recordings from more than 16 different categories of signals, including recordings of speech in different contexts and languages, musical compositions and performances from different genres. Non-human vocalizations from two bird species and two types of marine mammals were also analysed for comparison. The resulting patterns of AF variance across timescales were distinct to each of four natural categories of complex sound: speech, popular music, classical music and complex animal vocalizations. Comparisons within and across categories indicated that nested clustering in longer timescales was more prominent when prosodic variation was greater, and when sounds came from interactions among individuals, including interactions between speakers, musicians, and even killer whales. Nested clustering also was more prominent for music compared with speech, and reflected beat structure for popular music and self-similarity across timescales for classical music. In summary, hierarchical temporal structures reflect the behavioural and social processes underlying complex vocalizations and musical performances.

Towards a social functional account of laughter: Acoustic features convey reward, affiliation, and dominance.

Recent work has identified the physical features of smiles that accomplish three tasks fundamental to human social living: rewarding behavior, establishing and managing affiliative bonds, and negotiating social status. The current work extends the social functional account to laughter. Participants (N = 762) rated the degree to which reward, affiliation, or dominance (between-subjects) was conveyed by 400 laughter samples acquired from a commercial sound effects website. Inclusion of a fourth rating dimension, spontaneity, allowed us to situate the current approach in the context of existing laughter research, which emphasizes the distinction between spontaneous and volitional laughter. We used 11 acoustic properties extracted from the laugh samples to predict participants’ ratings. Actor sex moderated, and sometimes even reversed, the relation between acoustics and participants’ judgments. Spontaneous laughter appears to serve the reward function in the current framework, as similar acoustic properties guided perceiver judgments of spontaneity and reward: reduced voicing and increased pitch, increased duration for female actors, and increased pitch slope, center of gravity, first formant, and noisiness for male actors. Affiliation ratings diverged from reward in their sex-dependent relationship to intensity and, for females, reduced pitch range and raised second formant. Dominance displayed the most distinct pattern of acoustic predictors, including increased pitch range, reduced second formant in females, and decreased pitch variability in males. We relate the current findings to existing findings on laughter and human and non-human vocalizations, concluding laughter can signal much more that felt or faked amusement.

Central Nervous System Control of Voice and Swallowing.

This review of the central nervous control systems for voice and swallowing has suggested that the traditional concepts of a separation between cortical and limbic and brain stem control should be refined and be more integrative. For voice production, a separation of the nonhuman vocalization system from the human learned voice production system has been posited based primarily on studies of nonhuman primates. However, recent humans studies of emotionally based vocalizations and human volitional voice production have shown more integration between these two systems than previously proposed. Recent human studies have shown that reflexive vocalization as well as learned voice production not involving speech involve a common integrative system. However, recent studies of nonhuman primates have provided evidence that some cortical activity vocalization and cortical changes occur with training during vocal behavior. For swallowing, evidence from the macaque and functional brain imaging in humans indicates that the control for the pharyngeal phase of swallowing is not primarily under brain stem mechanisms as previously proposed. Studies suggest that the initiation and patterning of swallowing for the pharyngeal phase is also under active cortical control for both spontaneous as well as volitional swallowing in awake humans and nonhuman primates.

The animal nature of spontaneous human laughter

Laughter is a universally produced vocal signal that plays an important role in human social interaction. Researchers have distinguished between spontaneous and volitional laughter, but no empirical work has explored possible acoustic and perceptual differences. If spontaneous laughter is an honest signal of cooperative intent (e.g., derived from play breathing patterns), then the ability to mimic these sounds volitionally could have shaped perceptual systems to be attuned to aspects of spontaneous laughs that are harder to fake—features associated with phylogenetically older vocal control mechanisms. We extracted spontaneous laughs from conversations between friends and volitional laughs elicited by instruction without other provocation. In three perception experiments we found that, 1) participants could distinguish between spontaneous and volitional laughter, 2) when laugh speed was increased (duration decreased 33% and pitch held constant), all laughs were judged as more “real,” with judgment accuracy increasing for spontaneous laughter and decreasing for volitional laughter, and 3) when the laughs were slowed down (duration increased 260% and pitch altered proportionally), participants could not distinguish spontaneous laughs from nonhuman vocalizations but could identify volitional laughs as human-made. These findings and acoustic data suggest that spontaneous and volitional laughs are produced by different vocal systems, and that spontaneous laughter might share features with nonhuman animal vocalizations that volitional laughter does not.

Neural and behavioral investigations into timbre perception.

Timbre is the attribute that distinguishes sounds of equal pitch, loudness and duration. It contributes to our perception and discrimination of different vowels and consonants in speech, instruments in music and environmental sounds. Here we begin by reviewing human timbre perception and the spectral and temporal acoustic features that give rise to timbre in speech, musical and environmental sounds. We also consider the perception of timbre by animals, both in the case of human vowels and non-human vocalizations. We then explore the neural representation of timbre, first within the peripheral auditory system and later at the level of the auditory cortex. We examine the neural networks that are implicated in timbre perception and the computations that may be performed in auditory cortex to enable listeners to extract information about timbre. We consider whether single neurons in auditory cortex are capable of representing spectral timbre independently of changes in other perceptual attributes and the mechanisms that may shape neural sensitivity to timbre. Finally, we conclude by outlining some of the questions that remain about the role of neural mechanisms in behavior and consider some potentially fruitful avenues for future research.

Speech vs. singing: infants choose happier sounds.

Infants prefer speech to non-vocal sounds and to non-human vocalizations, and they prefer happy-sounding speech to neutral speech. They also exhibit an interest in singing, but there is little knowledge of their relative interest in speech and singing. The present study explored infants' attention to unfamiliar audio samples of speech and singing. In Experiment 1, infants 4–13 months of age were exposed to happy-sounding infant-directed speech vs. hummed lullabies by the same woman. They listened significantly longer to the speech, which had considerably greater acoustic variability and expressiveness, than to the lullabies. In Experiment 2, infants of comparable age who heard the lyrics of a Turkish children's song spoken vs. sung in a joyful/happy manner did not exhibit differential listening. Infants in Experiment 3 heard the happily sung lyrics of the Turkish children's song vs. a version that was spoken in an adult-directed or affectively neutral manner. They listened significantly longer to the sung version. Overall, happy voice quality rather than vocal mode (speech or singing) was the principal contributor to infant attention, regardless of age.

Segmental concatenation of individual signatures and context cues in banded mongoose (Mungos mungo) close calls

BackgroundAll animals are anatomically constrained in the number of discrete call types they can produce. Recent studies suggest that by combining existing calls into meaningful sequences, animals can increase the information content of their vocal repertoire despite these constraints. Additionally, signalers can use vocal signatures or cues correlated to other individual traits or contexts to increase the information encoded in their vocalizations. However, encoding multiple vocal signatures or cues using the same components of vocalizations usually reduces the signals' reliability. Segregation of information could effectively circumvent this trade-off. In this study we investigate how banded mongooses (Mungos mungo) encode multiple vocal signatures or cues in their frequently emitted graded single syllable close calls.ResultsThe data for this study were collected on a wild, but habituated, population of banded mongooses. Using behavioral observations and acoustical analysis we found that close calls contain two acoustically different segments. The first being stable and individually distinct, and the second being graded and correlating with the current behavior of the individual, whether it is digging, searching or moving. This provides evidence of Marler's hypothesis on temporal segregation of information within a single syllable call type. Additionally, our work represents an example of an identity cue integrated as a discrete segment within a single call that is independent from context. This likely functions to avoid ambiguity between individuals or receivers having to keep track of several context-specific identity cues.ConclusionsOur study provides the first evidence of segmental concatenation of information within a single syllable in non-human vocalizations. By reviewing descriptions of call structures in the literature, we suggest a general application of this mechanism. Our study indicates that temporal segregation and segmental concatenation of vocal signatures or cues is likely a common, but so far neglected, dimension of information coding in animal vocal communication. We argue that temporal segregation of vocal signatures and cues evolves in species where communication of multiple unambiguous signals is crucial, but is limited by the number of call types produced.

Vocal Tract Morphology Determines Species-Specific Features in Vocal Signals of Lemurs (Eulemur)

The source-filter theory describes vocal production as a two-stage process involving the generation of a sound source, with its own spectral structure, which is then filtered by the resonant properties of the vocal tract. This theory has been successfully applied to the study of animal vocal signals since the 1990s. As an extension, models reproducing vocal tract resonance can be used to reproduce formant patterns and to understand the role of vocal tract filtering in nonhuman vocalizations. We studied three congeneric lemur species —Eulemur fulvus, E. macaco, E. rubriventer— using morphological measurements to build computational models of the vocal tract to estimate formants, and acoustic analysis to measure formants from natural calls. We focused on call types emitted through the nose, without apparent articulation. On the basis of anatomical measurements, we modeled the vocal tract of each species as a series of concatenated tubes, with a cross-sectional area that changed along the tract to approximate the morphology of the larynx, the nasopharyngeal cavity, the nasal chambers, and the nostrils. For each species, we calculated the resonance frequencies in 2500 randomly generated vocal tracts, in which we simulated intraspecific length and size variation. Formant location and spacing showed significant species-specific differences determined by the length of the vocal tract. We then measured formants of a set of nasal vocalizations (“grunts”) recorded from captive lemurs of the same species. We found species-specific differences in the natural calls. This is the first evidence that morphology of the vocal tract is relevant in generating filter-related acoustic cues that potentially provide receivers with information about the species of the emitter.

Degrees of Separation: Are mirror neurons human language specific?

Event Abstract Back to Event Degrees of Separation: Are mirror neurons human language specific? Bernadine Cocks1, 2*, Graham Jamieson1, Ian Evans1 and Bruce Stevenson1 1 University of New England, Behavioural, Cognitive and Social Sciences (BCSS) - Psychology, Australia 2 University of South Australia, Division Office, Australia Since the discovery of mirror neurons in the late 1990s, a number of theories have been proposed concerning their role in human cognition, most notably in the area of human language. Although a handful of studies have examined such theories, none thus far have tested for differences in mirror neuron responses in the human brain between listening to human and non-human vocal communication. To this end, continuous EEG was recorded as human participants in the current study listened to a random selection of animal vocalizations including song bird tunes and monkey and ape calls, as well as a selection of everyday English language words. Event related band power decomposition is used to investigate differences in alpha desynchronization in known mirror neuron regions between listening to human and non-human communications. If mirror neurons respond selectively to human language, there should be no evidence of mirror neuron activity (event related alpha desynchronization) in relation to non-human vocalizations; if, however, mirror neurons do respond to non-human vocal communications, it is predicted that this response will be scale with phylogenetic distance from humans. Keywords: Mirror Neurons, Language, non-human vocalizations, EEG, event related alpha desynchronization Conference: ACNS-2012 Australasian Cognitive Neuroscience Conference, Brisbane, Australia, 29 Nov - 2 Dec, 2012. Presentation Type: Oral Presentation Topic: Language Citation: Cocks B, Jamieson G, Evans I and Stevenson B (2012). Degrees of Separation: Are mirror neurons human language specific?. Conference Abstract: ACNS-2012 Australasian Cognitive Neuroscience Conference. doi: 10.3389/conf.fnhum.2012.208.00026 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Oct 2012; Published Online: 07 Nov 2012. * Correspondence: Mrs. Bernadine Cocks, University of New England, Behavioural, Cognitive and Social Sciences (BCSS) - Psychology, Armidale, NSW, 2350, Australia, Bernie.Cocks@unisa.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Bernadine Cocks Graham Jamieson Ian Evans Bruce Stevenson Google Bernadine Cocks Graham Jamieson Ian Evans Bruce Stevenson Google Scholar Bernadine Cocks Graham Jamieson Ian Evans Bruce Stevenson PubMed Bernadine Cocks Graham Jamieson Ian Evans Bruce Stevenson Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Neural and behavioral correlates of auditory categorization

Goal-directed behavior is the essence of adaptation because it allows humans and other animals to respond dynamically to different environmental scenarios. Goal-directed behavior can be characterized as the formation of dynamic links between stimuli and actions. One important attribute of goal-directed behavior is that linkages can be formed based on how a stimulus is categorized. That is, links are formed based on the membership of a stimulus in a particular functional category. In this review, we review categorization with an emphasis on auditory categorization. We focus on the role of categorization in language and non-human vocalizations. We present behavioral data indicating that non-human primates categorize and respond to vocalizations based on differences in their putative meaning and not differences in their acoustics. Finally, we present evidence suggesting that the ventrolateral prefrontal cortex plays an important role in processing auditory objects and has a specific role in the representation of auditory categories.

Characterizing noise in nonhuman vocalizations: Acoustic analysis and human perception of barks by coyotes and dogs

Measuring noise as a component of mammalian vocalizations is of interest because of its potential relevance to the communicative function. However, methods for characterizing and quantifying noise are less well established than methods applicable to harmonically structured aspects of signals. Using barks of coyotes and domestic dogs, we compared six acoustic measures and studied how they are related to human perception of noisiness. Measures of harmonic-to-noise-ratio (HNR), percent voicing, and shimmer were found to be the best predictors of perceptual rating by human listeners. Both acoustics and perception indicated that noisiness was similar across coyote and dog barks, but within each species there was significant variation among the individual vocalizers. The advantages and disadvantages of the various measures are discussed.

From monkey-like action recognition to human language: An evolutionary framework for neurolinguistics

The article analyzes the neural and functional grounding of language skills as well as their emergence in hominid evolution, hypothesizing stages leading from abilities known to exist in monkeys and apes and presumed to exist in our hominid ancestors right through to modern spoken and signed languages. The starting point is the observation that both premotor area F5 in monkeys and Broca's area in humans contain a "mirror system" active for both execution and observation of manual actions, and that F5 and Broca's area are homologous brain regions. This grounded the mirror system hypothesis of Rizzolatti and Arbib (1998) which offers the mirror system for grasping as a key neural "missing link" between the abilities of our nonhuman ancestors of 20 million years ago and modern human language, with manual gestures rather than a system for vocal communication providing the initial seed for this evolutionary process. The present article, however, goes "beyond the mirror" to offer hypotheses on evolutionary changes within and outside the mirror systems which may have occurred to equip Homo sapiens with a language-ready brain. Crucial to the early stages of this progression is the mirror system for grasping and its extension to permit imitation. Imitation is seen as evolving via a so-called simple system such as that found in chimpanzees (which allows imitation of complex "object-oriented" sequences but only as the result of extensive practice) to a so-called complex system found in humans (which allows rapid imitation even of complex sequences, under appropriate conditions) which supports pantomime. This is hypothesized to have provided the substrate for the development of protosign, a combinatorially open repertoire of manual gestures, which then provides the scaffolding for the emergence of protospeech (which thus owes little to nonhuman vocalizations), with protosign and protospeech then developing in an expanding spiral. It is argued that these stages involve biological evolution of both brain and body. By contrast, it is argued that the progression from protosign and protospeech to languages with full-blown syntax and compositional semantics was a historical phenomenon in the development of Homo sapiens, involving few if any further biological changes.

Anatomical structures involved in non-human vocalization

In order to understand the functional morphology of the human voice producing system, we are in need of data on the vocal tract anatomy of other mammalian species. The larynges and vocal tracts of four species of Artiodactyla were investigated in combination with acoustic analyses of their respective calls. Different evolutionary specializations of laryngeal characters may lead to similar effects on sound production. In the investigated species, such specializations are: the elongation and mass increase of the vocal folds, the volume increase of the laryngeal vestibulum by an enlarged thyroid cartilage and the formation of laryngeal ventricles. Both the elongation of the vocal folds and the increase of the oscillating masses lower the fundamental frequency. The influence of an increased volume of the laryngeal vestibulum on sound production remains unclear. The anatomical and acoustic results are presented together with considerations about the habitats and the mating systems of the respective species.

A comparative study on the cortico-hypoglossal connections in primates, using biotin dextranamine

The anterograde projections of the motorcortical tongue area to the hypoglossal nucleus and neighbouring structures were studied in the rhesus monkey, squirrel monkey, saddle-back tamarin and tree shrew. Biotin dextranamine served as tracer. Direct projections into the hypoglossal nucleus were only found in the rhesus monkey and squirrel monkey. All four species, however, showed a direct projection into the dorsal and parvocellular reticular formation which in turn projects into the hypoglossal nucleus. The findings suggest a phylogenetic trend in the projections of the motorcortical tongue area from non-primate mammals via non-human primates to man in the sense that the cortico-motoneuronal connection is strengthened towards man. This might be one reason for the superior role the tongue plays in human vocal behaviour in contrast to non-human vocalization.

Speech evolved from vocalization, not mastication

The segmentation of phonation by articulation is a characteristic feature of speech that distinguishes it from most nonhuman vocalizations. However, apart from the trivial fact that speech uses some of the same muscles and, hence the same motoneurons and motorcortical areas used in chewing, there is no convincing evidence that syllable segmentation relies on the same pattern generator as mastication. Evidence for a differential cortical representation of syllable segmentation (“frame”) and syllable “content” is also meager.