scholarly journals A researcher's guide to the comparative assessment of vocal production learning

2021 ◽  
Vol 376 (1836) ◽  
pp. 20200237
Author(s):  
Ella Z. Lattenkamp ◽  
Stephen G. Hörpel ◽  
Janine Mengede ◽  
Uwe Firzlaff
Keyword(s):  
Sound Production ◽  
Production Systems ◽  
Experimental Studies ◽  
Vocal Learning ◽  
Comparative Assessment ◽  
Theme Issue ◽  
Acoustic Parameters ◽  
Animal Kingdom ◽  
Vocal Production ◽  
Five Factors

Vocal production learning (VPL) is the capacity to learn to produce new vocalizations, which is a rare ability in the animal kingdom and thus far has only been identified in a handful of mammalian taxa and three groups of birds. Over the last few decades, approaches to the demonstration of VPL have varied among taxa, sound production systems and functions. These discrepancies strongly impede direct comparisons between studies. In the light of the growing number of experimental studies reporting VPL, the need for comparability is becoming more and more pressing. The comparative evaluation of VPL across studies would be facilitated by unified and generalized reporting standards, which would allow a better positioning of species on any proposed VPL continuum. In this paper, we specifically highlight five factors influencing the comparability of VPL assessments: (i) comparison to an acoustic baseline, (ii) comprehensive reporting of acoustic parameters, (iii) extended reporting of training conditions and durations, (iv) investigating VPL function via behavioural, perception-based experiments and (v) validation of findings on a neuronal level. These guidelines emphasize the importance of comparability between studies in order to unify the field of vocal learning. This article is part of the theme issue ‘Vocal learning in animals and humans’.

scholarly journals Vocal production learning in mammals revisited

2021 ◽  
Vol 376 (1836) ◽  
pp. 20200244
Author(s):  
Vincent M. Janik ◽  
Mirjam Knörnschild
Keyword(s):  
Experimental Studies ◽  
Vocal Learning ◽  
Type Result ◽  
Theme Issue ◽  
Vocal Production ◽  
Learning Skills ◽  
Acoustic Models ◽  
Vocal Convergence ◽  
The Subject ◽  
Underlying Mechanisms

Vocal production learning, the ability to modify the structure of vocalizations as a result of hearing those of others, has been studied extensively in birds but less attention has been given to its occurrence in mammals. We summarize the available evidence for vocal learning in mammals from the last 25 years, updating earlier reviews on the subject. The clearest evidence comes from cetaceans, pinnipeds, elephants and bats where species have been found to copy artificial or human language sounds, or match acoustic models of different sound types. Vocal convergence, in which parameter adjustments within one sound type result in similarities between individuals, occurs in a wider range of mammalian orders with additional evidence from primates, mole-rats, goats and mice. Currently, the underlying mechanisms for convergence are unclear with vocal production learning but also usage learning or matching physiological states being possible explanations. For experimental studies, we highlight the importance of quantitative comparisons of seemingly learned sounds with vocal repertoires before learning started or with species repertoires to confirm novelty. Further studies on the mammalian orders presented here as well as others are needed to explore learning skills and limitations in greater detail. This article is part of the theme issue ‘Vocal learning in animals and humans’.

scholarly journals Vocal production learning in the pale spear-nosed bat, Phyllostomus discolor

2020 ◽  
Vol 16 (4) ◽  
pp. 20190928 ◽  
Author(s):  
Ella Z. Lattenkamp ◽  
Sonja C. Vernes ◽  
Lutz Wiegrebe
Keyword(s):  
Mammalian Species ◽  
Vocal Learning ◽  
Acoustic Signals ◽  
Auditory Target ◽  
Animal Kingdom ◽  
Vocal Production ◽  
Learning Capacity ◽  
Directional Change ◽  
Set Up ◽  
Phyllostomus Discolor

Vocal production learning (VPL), or the ability to modify vocalizations through the imitation of sounds, is a rare trait in the animal kingdom. While humans are exceptional vocal learners, few other mammalian species share this trait. Owing to their singular ecology and lifestyle, bats are highly specialized for the precise emission and reception of acoustic signals. This specialization makes them ideal candidates for the study of vocal learning, and several bat species have previously shown evidence supportive of vocal learning. Here we use a sophisticated automated set-up and a contingency training paradigm to explore the vocal learning capacity of pale spear-nosed bats. We show that these bats are capable of directional change of the fundamental frequency of their calls according to an auditory target. With this study, we further highlight the importance of bats for the study of vocal learning and provide evidence for the VPL capacity of the pale spear-nosed bat.

scholarly journals Re-evaluating vocal production learning in non-oscine birds

2021 ◽  
Vol 376 (1836) ◽  
Author(s):  
Carel ten Cate
Keyword(s):  
Comparative Studies ◽  
Comparative Research ◽  
Vocal Learning ◽  
Limited Evidence ◽  
Theme Issue ◽  
Vocal Production ◽  
Broad Definition ◽  
Interspecific Variations ◽  
Phylogenetic Framework ◽  
Definition Of

The study of vocal production learning in birds is heavily biased towards oscine songbirds, making the songbird model the reference for comparative studies. However, as vocal learning was probably ancestral in songbirds, interspecific variations might all be variations on a single theme and need not be representative of the nature and characteristics of vocal learning in other bird groups. To assess the possible mechanisms of vocal learning and its evolution therefore requires knowledge about independently evolved incidences of vocal learning. This review examines the presence and nature of vocal production learning in non-songbirds. Using a broad definition of vocal learning and a comparative phylogenetic framework, I evaluate the evidence for vocal learning and its characteristics in non-oscine birds, including well-known vocal learners such as parrots and hummingbirds but also (putative) cases from other taxa. Despite the sometimes limited evidence, it is clear that vocal learning occurs in a range of different, non-related, taxa and can be caused by a variety of mechanisms. It is more widespread than often realized, calling for more systematic studies. Examining this variation may provide a window onto the evolution of vocal learning and increase the value of comparative research for understanding vocal learning in humans. This article is part of the theme issue ‘Vocal learning in animals and humans’.

scholarly journals Morphological facilitators for vocal learning explored through the syrinx anatomy of a basal hummingbird

2020 ◽  
Author(s):  
Amanda Monte ◽  
Alexander F. Cerwenka ◽  
Bernhard Ruthensteiner ◽  
Manfred Gahr ◽  
Daniel N. Düring
Keyword(s):  
Sound Production ◽  
Three Dimensional ◽  
Vocal Learning ◽  
Dimensional Structure ◽  
Micro Computed Tomography ◽  
Vocal Production ◽  
Precise Control ◽  
Acoustic Space ◽  
Biomechanical Factors ◽  
Intrinsic Musculature

AbstractVocal learning is a rare evolutionary trait that evolved independently in three avian clades: songbirds, parrots, and hummingbirds. Although the anatomy and mechanisms of sound production in songbirds are well understood, little is known about the hummingbird’s vocal anatomy. We use high-resolution micro-computed tomography (μCT) and microdissection to reveal the three-dimensional structure of the syrinx, the vocal organ of the black jacobin (Florisuga fusca), a phylogenetically basal hummingbird species. We identify three unique features of the black jacobin’s syrinx: (i) a shift in the position of the syrinx to the outside of the thoracic cavity and the related loss of the sterno-tracheal muscle, (ii) complex intrinsic musculature, oriented dorso-ventrally, and (iii) ossicles embedded in the medial vibratory membranes. Their syrinx morphology allows vibratory decoupling, precise control of complex acoustic parameters, and a large redundant acoustic space that may be key biomechanical factors facilitating the occurrence of vocal production learning.

scholarly journals Towards a new taxonomy of primate vocal production learning

2019 ◽  
Vol 375 (1789) ◽  
pp. 20190045 ◽  
Author(s):  
Julia Fischer ◽  
Kurt Hammerschmidt
Keyword(s):  
Nonhuman Primates ◽  
Animal Communication ◽  
Vocal Learning ◽  
Auditory Comprehension ◽  
Theme Issue ◽  
Vocal Production ◽  
Evolution Of Speech ◽  
Ontogenetic Trajectory ◽  
Auditory Experience ◽  
Species Specific

The extent to which vocal learning can be found in nonhuman primates is key to reconstructing the evolution of speech. Regarding the adjustment of vocal output in relation to auditory experience (vocal production learning in the narrow sense), effects on the ontogenetic trajectory of vocal development as well as adjustment to group-specific call features have been found. Yet, a comparison of the vocalizations of different primate genera revealed striking similarities in the structure of calls and repertoires in different species of the same genus, indicating that the structure of nonhuman primate vocalizations is highly conserved. Thus, modifications in relation to experience only appear to be possible within relatively tight species-specific constraints. By contrast, comprehension learning may be extremely rapid and open-ended. In conjunction, these findings corroborate the idea of an ancestral independence of vocal production and auditory comprehension learning. To overcome the futile debate about whether or not vocal production learning can be found in nonhuman primates, we suggest putting the focus on the different mechanisms that may mediate the adjustment of vocal output in response to experience; these mechanisms may include auditory facilitation and learning from success. This article is part of the theme issue ‘What can animal communication teach us about human language?’

scholarly journals Vocal imitations and production learning by Australian musk ducks ( Biziura lobata )

2021 ◽  
Vol 376 (1836) ◽  
Author(s):  
Carel ten Cate ◽  
Peter J. Fullagar
Keyword(s):  
Vocal Learning ◽  
Theme Issue ◽  
Vocal Production ◽  
Flexible Control ◽  
Human Voice ◽  
Black Duck ◽  
Basal Clade ◽  
Rearing Conditions ◽  
Repetitive Structure ◽  
Different Origins

Acquiring vocalizations by learning them from other individuals is only known from a limited number of animal groups. For birds, oscine and some suboscine songbirds, parrots and hummingbirds demonstrate this ability. Here, we provide evidence for vocal learning in a member of a basal clade of the avian phylogeny: the Australian musk duck ( Biziura lobata ). A hand-reared individual imitated a slamming door and a human voice, and a female-reared individual imitated Pacific black duck quacks. These sounds have been described before, but were never analysed in any detail and went so far unnoticed by researchers of vocal learning. The imitations were produced during the males' advertising display. The hand-reared male used at least three different vocalizations in the display context, with each one produced in the same stereotyped and repetitive structure as the normal display sounds. Sounds of different origins could be combined in one vocalization and at least some of the imitations were memorized at an early age, well before they were produced later in life. Together with earlier observations of vocal differences between populations and deviant vocalizations in captive-reared individuals, these observations demonstrate the presence of advanced vocal learning at a level comparable to that of songbirds and parrots. We discuss the rearing conditions that may have given rise to the imitations and suggest that the structure of the duck vocalizations indicates a quite sophisticated and flexible control over the vocal production mechanism. The observations support the hypothesis that vocal learning in birds evolved in several groups independently rather than evolving once with several losses. This article is part of the theme issue ‘Vocal learning in animals and humans’.

scholarly journals Killer whales are capable of vocal learning

2006 ◽  
Vol 2 (4) ◽  
pp. 509-512 ◽  
Author(s):  
Andrew D Foote ◽  
Rachael M Griffin ◽  
David Howitt ◽  
Lisa Larsson ◽  
Patrick J.O Miller ◽  
...  
Keyword(s):  
Sound Production ◽  
Vocal Learning ◽  
Physical Structure ◽  
Learning Ability ◽  
Killer Whales ◽  
Sea Lion ◽  
California Sea Lion ◽  
Vocal Production ◽  
Vocal Behaviour ◽  
Call Usage

The production learning of vocalizations by manipulation of the sound production organs to alter the physical structure of sound has been demonstrated in only a few mammals. In this natural experiment, we document the vocal behaviour of two juvenile killer whales, Orcinus orca , separated from their natal pods, which are the only cases of dispersal seen during the three decades of observation of their populations. We find mimicry of California sea lion ( Zalophus californianus ) barks, demonstrating the vocal production learning ability for one of the calves. We also find differences in call usage (compared to the natal pod) that may reflect the absence of a repertoire model from tutors or some unknown effect related to isolation or context.

scholarly journals Variation in vocal production learning across songbirds

2021 ◽  
Vol 376 (1836) ◽  
Author(s):  
William A. Searcy ◽  
Jill Soha ◽  
Susan Peters ◽  
Stephen Nowicki
Keyword(s):  
Vocal Learning ◽  
Normal Range ◽  
Theme Issue ◽  
Vocal Production ◽  
Song Development

Songbirds as a whole are considered to be vocal production learners, meaning that they modify the structure of their vocalizations as a result of experience with the vocalizations of others. The more than 4000 species of songbirds, however, vary greatly in crucial features of song development. Variable features include: (i) the normality of the songs of early-deafened birds, reflecting the importance of innate motor programmes in song development; (ii) the normality of the songs of isolation-reared birds, reflecting the combined importance of innate auditory templates and motor programmes; (iii) the degree of selectivity in choice of external models; (iv) the accuracy of copying from external models; and (v) whether or not learning from external models continues into adulthood. We suggest that because of this variability, some songbird species, specifically those that are able to develop songs in the normal range without exposure to external models, can be classified as limited vocal learners. Those species that require exposure to external models to develop songs in the normal range can be considered complex vocal learners. This article is part of the theme issue ‘Vocal learning in animals and humans’.

scholarly journals Vocal Creativity in Elephant Sound Production

Biology ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 750
Author(s):  
Angela S. Stoeger ◽  
Anton Baotic ◽  
Gunnar Heilmann
Keyword(s):  
Cognitive Abilities ◽  
Positive Reinforcement ◽  
Sound Production ◽  
Vocal Learning ◽  
Learning Processes ◽  
Fine Tuning ◽  
Social Feedback ◽  
Nasal Tissue ◽  
Production Techniques ◽  
Production Mechanisms

How do elephants achieve their enormous vocal flexibility when communicating, imitating or creating idiosyncratic sounds? The mechanisms that underpin this trait combine motoric abilities with vocal learning processes. We demonstrate the unusual production techniques used by five African savanna elephants to create idiosyncratic sounds, which they learn to produce on cue by positive reinforcement training. The elephants generate these sounds by applying nasal tissue vibration via an ingressive airflow at the trunk tip, or by contracting defined superficial muscles at the trunk base. While the production mechanisms of the individuals performing the same sound categories are similar, they do vary in fine-tuning, revealing that each individual has its own specific sound-producing strategy. This plasticity reflects the creative and cognitive abilities associated with ‘vocal’ learning processes. The fact that these sounds were reinforced and cue-stimulated suggests that social feedback and positive reinforcement can facilitate vocal creativity and vocal learning behavior in elephants. Revealing the mechanism and the capacity for vocal learning and sound creativity is fundamental to understanding the eloquence within the elephants’ communication system. This also helps to understand the evolution of human language and of open-ended vocal systems, which build upon similar cognitive processes.

scholarly journals Adding colour-realistic video images to audio playbacks increases stimulus engagement but does not enhance vocal learning in zebra finches

2021 ◽  
Author(s):  
Judith M. Varkevisser ◽  
Ralph Simon ◽  
Ezequiel Mendoza ◽  
Martin How ◽  
Idse van Hijlkema ◽  
...  
Keyword(s):  
Visual Cues ◽  
Sound Production ◽  
Visual Stimuli ◽  
Vocal Learning ◽  
Song Learning ◽  
Frame Rate ◽  
Zebra Finches ◽  
Video Content ◽  
Biologically Relevant ◽  
Video Images

AbstractBird 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.

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