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Favaro L, Zanoli A, Ludynia K, Snyman A, Carugati F, Friard O, Scaglione FE, Manassero L, Valazza A, Mathevon N, Gamba M, Reby D. Vocal tract shape variation contributes to individual vocal identity in African penguins. Proc Biol Sci 2023; 290:20231029. [PMID: 37817600 PMCID: PMC10565386 DOI: 10.1098/rspb.2023.1029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 09/18/2023] [Indexed: 10/12/2023] Open
Abstract
Variation in formant frequencies has been shown to affect social interactions and sexual competition in a range of avian species. Yet, the anatomical bases of this variation are poorly understood. Here, we investigated the morphological correlates of formants production in the vocal apparatus of African penguins. We modelled the geometry of the supra-syringeal vocal tract of 20 specimens to generate a population of virtual vocal tracts with varying dimensions. We then estimated the acoustic response of these virtual vocal tracts and extracted the centre frequency of the first four predicted formants. We demonstrate that: (i) variation in length and cross-sectional area of vocal tracts strongly affects the formant pattern, (ii) the tracheal region determines most of this variation, and (iii) the skeletal size of penguins does not correlate with the trachea length and consequently has relatively little effect on formants. We conclude that in African penguins, while the variation in vocal tract geometry generates variation in resonant frequencies supporting the discrimination of conspecifics, such variation does not provide information on the emitter's body size. Overall, our findings advance our understanding of the role of formant frequencies in bird vocal communication.
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Affiliation(s)
- Livio Favaro
- ENES Bioacoustics Research Laboratory, CRNL, University of Saint-Etienne, CNRS, Inserm, Saint-Etienne, France
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Anna Zanoli
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Katrin Ludynia
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa
- Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, South Africa
| | - Albert Snyman
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa
| | - Filippo Carugati
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Olivier Friard
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | | | - Luca Manassero
- Department of Veterinary Science, University of Turin, Turin, Italy
| | - Alberto Valazza
- Department of Veterinary Science, University of Turin, Turin, Italy
| | - Nicolas Mathevon
- ENES Bioacoustics Research Laboratory, CRNL, University of Saint-Etienne, CNRS, Inserm, Saint-Etienne, France
- Institut Universitaire de France, Ministry of Higher Education, Research and Innovation, 1 rue Descartes, 75231 Paris Cedex 05, France
| | - Marco Gamba
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - David Reby
- ENES Bioacoustics Research Laboratory, CRNL, University of Saint-Etienne, CNRS, Inserm, Saint-Etienne, France
- Institut Universitaire de France, Ministry of Higher Education, Research and Innovation, 1 rue Descartes, 75231 Paris Cedex 05, France
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Beeck VC, Heilmann G, Kerscher M, Stoeger AS. Sound Visualization Demonstrates Velopharyngeal Coupling and Complex Spectral Variability in Asian Elephants. Animals (Basel) 2022; 12:2119. [PMID: 36009709 PMCID: PMC9404934 DOI: 10.3390/ani12162119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/02/2022] [Accepted: 08/13/2022] [Indexed: 12/05/2022] Open
Abstract
Sound production mechanisms set the parameter space available for transmitting biologically relevant information in vocal signals. Low-frequency rumbles play a crucial role in coordinating social interactions in elephants' complex fission-fusion societies. By emitting rumbles through either the oral or the three-times longer nasal vocal tract, African elephants alter their spectral shape significantly. In this study, we used an acoustic camera to visualize the sound emission of rumbles in Asian elephants, which have received far less research attention than African elephants. We recorded nine adult captive females and analyzed the spectral parameters of 203 calls, including vocal tract resonances (formants). We found that the majority of rumbles (64%) were nasally emitted, 21% orally, and 13% simultaneously through the mouth and trunk, demonstrating velopharyngeal coupling. Some of the rumbles were combined with orally emitted roars. The nasal rumbles concentrated most spectral energy in lower frequencies exhibiting two formants, whereas the oral and mixed rumbles contained higher formants, higher spectral energy concentrations and were louder. The roars were the loudest, highest and broadest in frequency. This study is the first to demonstrate velopharyngeal coupling in a non-human animal. Our findings provide a foundation for future research into the adaptive functions of the elephant acoustic variability for information coding, localizability or sound transmission, as well as vocal flexibility across species.
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Affiliation(s)
- Veronika C. Beeck
- Department of Behavioural and Cognitive Biology, University of Vienna, 1030 Vienna, Austria
| | | | | | - Angela S. Stoeger
- Department of Behavioural and Cognitive Biology, University of Vienna, 1030 Vienna, Austria
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Redaelli L, Galimberti F, Sanvito S. Phenotype constrains the vocal tract in the most dimorphic mammal, the southern elephant seal. CAN J ZOOL 2022. [DOI: 10.1139/cjz-2021-0188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The study of mammal acoustic communication was revolutionized by the application of the source-filter theory, originally developed for human speech. The theory states that the vocal tract is constrained by body anatomy and, therefore, creates a structural link between phenotype and acoustic formants, providing a basis for honest signalling. The phenotype-formants link was validated in many species, but the phenotype-vocal tract link was rarely assessed. We used 2D videogrammetry to estimate the vocal tract length of wild southern elephant seal males (Mirounga leonina Linnaeus, 1758) during their normal vocalization behaviour. We showed that: 1) the vocal tract can be measured non-invasively in a wild large mammal; 2) the vocal tract depends on the structural phenotype (age, body length, and skull size); 3) the nasal tract is more related to the structural phenotype than the buccal tract; 4) the dependence on size, and body length in particular, is stronger than the dependence on age. All together, the phenotypic constraint on vocal tract provides the anatomical basis for honest signalling in elephant seals.
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Affiliation(s)
- Laura Redaelli
- Università degli Studi di Milano, 9304, Dipartimento di Scienze Naturali, Milano, Italy, 20122
| | - Filippo Galimberti
- Elephant Seal Research Group, 263286, Sea Lion Island, FALKLAND, Falkland Islands [Malvinas]
| | - Simona Sanvito
- Elephant Seal Research Group, 263286, Sea Lion Island, FALKLAND, Falkland Islands [Malvinas]
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Pisanski K, Anikin A, Reby D. Vocal size exaggeration may have contributed to the origins of vocalic complexity. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200401. [PMID: 34775821 PMCID: PMC8591380 DOI: 10.1098/rstb.2020.0401] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 06/14/2021] [Indexed: 01/05/2023] Open
Abstract
Vocal tract elongation, which uniformly lowers vocal tract resonances (formant frequencies) in animal vocalizations, has evolved independently in several vertebrate groups as a means for vocalizers to exaggerate their apparent body size. Here, we propose that smaller speech-like articulatory movements that alter only individual formants can serve a similar yet less energetically costly size-exaggerating function. To test this, we examine whether uneven formant spacing alters the perceived body size of vocalizers in synthesized human vowels and animal calls. Among six synthetic vowel patterns, those characterized by the lowest first and second formant (the vowel /u/ as in 'boot') are consistently perceived as produced by the largest vocalizer. Crucially, lowering only one or two formants in animal-like calls also conveys the impression of a larger body size, and lowering the second and third formants simultaneously exaggerates perceived size to a similar extent as rescaling all formants. As the articulatory movements required for individual formant shifts are minor compared to full vocal tract extension, they represent a rapid and energetically efficient mechanism for acoustic size exaggeration. We suggest that, by favouring the evolution of uneven formant patterns in vocal communication, this deceptive strategy may have contributed to the origins of the phonemic diversification required for articulated speech. This article is part of the theme issue 'Voice modulation: from origin and mechanism to social impact (Part II)'.
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Affiliation(s)
- Katarzyna Pisanski
- Equipe de Neuro-Ethologie Sensorielle, CNRS and Jean Monnet University of Saint Étienne, UMR 5293, 42023, St-Étienne, France
| | - Andrey Anikin
- Equipe de Neuro-Ethologie Sensorielle, CNRS and Jean Monnet University of Saint Étienne, UMR 5293, 42023, St-Étienne, France
- Division of Cognitive Science, Lund University, 22100 Lund, Sweden
| | - David Reby
- Equipe de Neuro-Ethologie Sensorielle, CNRS and Jean Monnet University of Saint Étienne, UMR 5293, 42023, St-Étienne, France
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Li P, Ross CF, Luo ZX. Morphological disparity and evolutionary transformations in the primate hyoid apparatus. J Hum Evol 2021; 162:103094. [PMID: 34808474 DOI: 10.1016/j.jhevol.2021.103094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 10/03/2021] [Accepted: 10/03/2021] [Indexed: 10/19/2022]
Abstract
The hyoid apparatus plays an integral role in swallowing, respiration, and vocalization in mammals. Most placental mammals have a rod-shaped basihyal connected to the basicranium via both soft tissues and a mobile bony chain-the anterior cornu-whereas anthropoid primates have broad, shield-like or even cup-shaped basihyals suspended from the basicranium by soft tissues only. How the unique anthropoid hyoid morphology evolved is unknown, and hyoid morphology of nonanthropoid primates is poorly documented. Here we use phylogenetic comparative methods and linear morphometrics to address knowledge gaps in hyoid evolution among primates and their euarchontan outgroups. We find that dermopterans have variable reduction of cornu elements. Cynocephalus volans are sexually dimorphic in hyoid morphology. Tupaia and all lemuroids except Daubentonia have a fully ossified anterior cornu connecting a rod-shaped basihyal to the basicranium; this is the ancestral mammalian pattern that is also characteristic of the last common ancestor of Primates. Haplorhines exhibit a reduced anterior cornu, and anthropoids underwent further increase in basihyal aspect ratio values and in relative basihyal volume. Convergent with haplorhines, lorisoid strepsirrhines independently evolved a broad basihyal and reduced anterior cornua. While a reduced anterior cornu is hypothesized to facilitate vocal tract lengthening and lower formant frequencies in some mammals, our results suggest vocalization adaptations alone are unlikely to drive the iterative reduction of anterior cornua within Primates. Our new data on euarchontan hyoid evolution provide an anatomical basis for further exploring the form-function relationships of the hyoid across different behaviors, including vocalization, chewing, and swallowing.
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Affiliation(s)
- Peishu Li
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, IL, 60637, USA.
| | - Callum F Ross
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, IL, 60637, USA
| | - Zhe-Xi Luo
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, IL, 60637, USA
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Volodin IA, Volodina EV, Frey R. Rutting vocal display in male impala (Aepyceros melampus) and overlap with alarm context. Front Zool 2021; 18:2. [PMID: 33413460 PMCID: PMC7792082 DOI: 10.1186/s12983-020-00383-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 12/16/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The rutting vocal display of male impala Aepyceros melampus is unique for its complexity among ruminants. This study investigates bouts of rutting calls produced towards potential mates and rival males by free-ranging male impala in Namibia. In particular, a comparison of male rutting and alarm snorts is conducted, inspired by earlier findings of mate guarding by using alarm snorts in male topi Damaliscus lunatus. RESULTS Rutting male impala produced 4-38 (13.5 ± 6.5) rutting calls per bout. We analyzed 201 bouts, containing in total 2709 rutting calls of five types: continuous roars produced within a single exhalation-inhalation cycle; interrupted roars including few exhalation-inhalation cycles; pant-roars distinctive by a pant-phase with rapidly alternating inhalations and exhalations; usual snorts lacking any roar part; and roar-snorts starting with a short roar part. Bouts mostly started and ended with usual snorts. Continuous roars were the shortest roars. The average duration of the exhalatory phase was longest in the continuous roars and shortest in the pant-roars. The average fundamental frequency (49.7-51.4 Hz) did not differ between roar types. Vocal tract length, calculated by using measurements of the first four vocal tract resonances (formants), ranged within 381-382 mm in all roar types. In the studied male impala, rutting snorts within bouts of rutting calls were longer and had higher values of the upper quartile in the call spectra than alarm snorts produced towards potential danger. CONCLUSIONS Additional inhalations during the emission of the interrupted and pant-roars prolong their duration compared to the continuous roars but do not affect the fundamental frequency or the degree of larynx retraction while roaring. Alarm snorts are separated from one another by large intervals, whereas the intervals between rutting snorts within bouts are short. Sometimes, rutting snorts alternate with roars, whereas alarm snorts do not. Therefore, it is not the acoustic structure of individual snorts but the temporal sequence and the occasional association with another call type that defines snorts as either rutting or alarm snorts. The rutting snorts of male impala may function to attract the attention of receptive females and delay their departure from a male's harem or territory.
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Affiliation(s)
- Ilya A Volodin
- Department of Vertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Vorobievy Gory, 12/1, Moscow, 119234, Russia.
- Department of Behaviour and Behavioural Ecology of Mammals, A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia.
| | - Elena V Volodina
- Department of Behaviour and Behavioural Ecology of Mammals, A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia
| | - Roland Frey
- Department of Reproduction Management, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
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Frey R, Volodin IA, Volodina EV, Efremova KO, Menges V, Portas R, Melzheimer J, Fritsch G, Gerlach C, von Dörnberg K. Savannah roars: The vocal anatomy and the impressive rutting calls of male impala (Aepyceros melampus) - highlighting the acoustic correlates of a mobile larynx. J Anat 2019; 236:398-424. [PMID: 31777085 PMCID: PMC7018640 DOI: 10.1111/joa.13114] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2019] [Indexed: 11/29/2022] Open
Abstract
A retractable larynx and adaptations of the vocal folds in the males of several polygynous ruminants serve for the production of rutting calls that acoustically announce larger than actual body size to both rival males and potential female mates. Here, such features of the vocal tract and of the sound source are documented in another species. We investigated the vocal anatomy and laryngeal mobility including its acoustical effects during the rutting vocal display of free‐ranging male impala (Aepyceros melampus melampus) in Namibia. Male impala produced bouts of rutting calls (consisting of oral roars and interspersed explosive nasal snorts) in a low‐stretch posture while guarding a rutting territory or harem. For the duration of the roars, male impala retracted the larynx from its high resting position to a low mid‐neck position involving an extensible pharynx and a resilient connection between the hyoid apparatus and the larynx. Maximal larynx retraction was 108 mm based on estimates in video single frames. This was in good concordance with 91‐mm vocal tract elongation calculated on the basis of differences in formant dispersion between roar portions produced with the larynx still ascended and those produced with maximally retracted larynx. Judged by their morphological traits, the larynx‐retracting muscles of male impala are homologous to those of other larynx‐retracting ruminants. In contrast, the large and massive vocal keels are evolutionary novelties arising by fusion and linear arrangement of the arytenoid cartilage and the canonical vocal fold. These bulky and histologically complex vocal keels produced a low fundamental frequency of 50 Hz. Impala is another ruminant species in which the males are capable of larynx retraction. In addition, male impala vocal folds are spectacularly specialized compared with domestic bovids, allowing the production of impressive, low‐frequency roaring vocalizations as a significant part of their rutting behaviour. Our study expands knowledge on the evolutionary variation of vocal fold morphology in mammals, suggesting that the structure of the mammalian sound source is not always human‐like and should be considered in acoustic analysis and modelling.
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Affiliation(s)
- Roland Frey
- Department of Reproduction Management, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Ilya A Volodin
- Faculty of Biology, Department of Vertebrate Zoology, Lomonosov Moscow State University, Moscow, Russia.,Scientific Research Department, Moscow Zoo, Moscow, Russia
| | | | | | - Vera Menges
- Department of Evolutionary Ecology, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Ruben Portas
- Department of Evolutionary Ecology, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Jörg Melzheimer
- Department of Evolutionary Ecology, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Guido Fritsch
- Department of Reproduction Management, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
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Rutting roars in native Pannonian red deer of Southern Hungary and the evidence of acoustic divergence of male sexual vocalization between Eastern and Western European red deer (Cervus elaphus). Mamm Biol 2019. [DOI: 10.1016/j.mambio.2018.10.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Knight K. Fallow deer bucks croon through their noses to sound bigger. J Exp Biol 2018. [DOI: 10.1242/jeb.188052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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