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Cited by 29Animal Vocal Communication and BehaviorVoice and Speech DisordersPhonetics and Phonology Research

Subglottal pressure and fundamental frequency control in contact calls of juvenile Alligator mississippiensis

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Riede, Tobias, Tokuda, Isao T., Farmer, C. G.·2011·Journal of Experimental Biology
DOI 10.1242/jeb.051110PMC PMC3160820
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Abstract

SUMMARY: Vocalization is rare among non-avian reptiles, with the exception of the crocodilians, the sister taxon of birds. Crocodilians have a complex vocal repertoire. Their vocal and respiratory system is not well understood but appears to consist of a combination of features that are also found in the extremely vocal avian and mammalian taxa. Anatomical studies suggest that the alligator larynx is able to abduct and adduct the vocal folds, but not to elongate or shorten them, and is therefore lacking a key regulator of frequency, yet alligators can modulate fundamental frequency remarkably well. We investigated the morphological and physiological features of sound production in alligators. Vocal fold length scales isometrically across a wide range of alligator body sizes. The relationship between fundamental frequency and subglottal pressure is significant in some individuals at some isolated points, such as call onset and position of maximum fundamental frequency. The relationship is not consistent over large segments of the call. Fundamental frequency can change faster than expected by pressure changes alone, suggesting an active motor pattern controls frequency and is intrinsic to the larynx. We utilized a two-mass vocal fold model to test whether abduction and adduction could generate this motor pattern. The fine-tuned interplay between subglottal pressure and glottal adduction can achieve frequency modulations much larger than those resulting from subglottal pressure variations alone and of similar magnitude, as observed in alligator calls. We conclude that the alligator larynx represents a sound source with only two control parameters (subglottal pressure and vocal fold adduction) in contrast to the mammalian larynx in which three parameters can be altered to modulate frequency (subglottal pressure, vocal fold adduction and length/tension).

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  • Vocalisations such as growls, roars, and bellows are produced by air pressure travelling through the laryngeal vocal folds causing them to vibrate through the trachea, with resonance produced by the vocal tract.

    “These include vocalisations such as growls, roars (in crocodiles) and bellows (in alligators), all of which are produced by air pressure travelling through the laryngeal vocal folds causing them to vibrate through the trachea, with resonance produced by the vocal tract (Riede et al. 2011; Reber et al. 2017).”

    From Roars, Rumbles, and Resonance: A Systematic Review and Meta‐Analysis of Crocodylian Acoustic Signals (2026) · cites this paper as Riede et al. 2011

    The Introduction and Materials and Methods describe airflow through the alligator larynx causing vocal-fold vibration, and the Discussion mentions alligator bellows. But the study examines juvenile contact calls, not the production of growls, crocodile roars, or bellows; the Discussion says the vocal tract’s contribution to sound properties needs further study, so it does not establish the claimed resonance mechanism. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • Percussion is a means of acoustic signalling involving sounds created by body-body or body‐object striking, such as jaw pops and headslaps.

    “A third means of acoustic signalling is percussion, involving sounds created by body–body or body‐object striking, such as jaw pops and headslaps (Vergne et al. 2009; Riede et al. 2011, 2015).”

    From Roars, Rumbles, and Resonance: A Systematic Review and Meta‐Analysis of Crocodylian Acoustic Signals (2026) · cites this paper as Riede et al. 2011

    The Materials and Methods and Results passages describe juvenile alligator contact calls produced by vocalization, not percussion. Searches for jaw pops, headslaps, striking, and non-vocal acoustic signals found no passage in our copy addressing the claimed form of signalling; page numbers were unavailable. (LLM, conf=0.76)

    Experimental — accuracy not yet measured

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Research works printed but not linked: 6

  1. Herzog H. A. Burghardt G. M. (1977). Vocalizations in juvenile crocodilians. Z. Tierpsychol. 44, 294- 304 930443
  2. Martin W. F. (1972). Evolution of vocalization in the genus Bufo. In Evolution in the Genus Bufo (ed. Blair W. F.), pp. 279- 309 Austin: University of Texas Press
  3. Müller J. (1839). Compensation der physischen Kräfte am menschlichen Stimmorgan, pp. 1- 54 Berlin, Hirschwald Verlag
  4. Nishizawa N. Sawashima M. Yonemoto K. (1988). Vocal fold length in vocal pitch change. In Vocal physiology: Voice Production, Mechanisms and Functions. (ed. Fujimura O.), pp. 75- 82 New York: Raven Press
  5. Riede T. Fisher J. H. Goller F. (2010a). Sexual dimorphism of the sound generating labia and the cartilaginous framework in the syrinx of zebra finches. PLoS One 5, e11368 20614010 PMC2894075
  6. Titze I. R. Riede T. Popollo P. (2008). Vocal exercises to determine nonlinear source-filter interaction. J. Acoust. Soc. Am. 123, 1902- 1915 18396999 PMC2677316

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Authors
Riede, T., Tokuda, I. T., & Farmer, C. G.
Affiliations
  • University of Utah (US)
  • Ritsumeikan University (JP)
Corresponding author
Riede, Tobias
ORCID
Venue
Journal of Experimental Biology
Publisher
The Company of Biologists
Published
2011-09-15
Volume
214
Issue
18
Pages
3082-3095
ISSN
  • 0022-0949 (ISSN-L)
  • 1477-9145
DOI
10.1242/jeb.051110
PMC
PMC3160820
OpenAlex
W2100318839
Cited by
29
References
80
Citations by year
2026: 1 · 2025: 2 · 2024: 1 · 2023: 1 · 2022: 1 · 2021: 4 · 2020: 3 · 2019: 3 · 2018: 1 · 2016: 2 · 2015: 5 · 2013: 3 · 2012: 2
FWCI
1.23
Type
journal article
Language
en
Open access
Licence
Locations
  • Journal of Experimental Biology (publishedVersion, cc-by-nc-sa)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by-nc-sa)
  • PubMed Central (publishedVersion, cc-by-nc-sa)
  • PubMed (publishedVersion)
Funders
  • Japan Society for the Promotion of Science (23300071, 23560446, 23360047)
  • National Institute on Deafness and Other Communication Disorders (R01DC006876, R01DC008612)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Developmental Biology › Animal Vocal Communication and Behavior
  • Health Sciences › Medicine › Physiology › Voice and Speech Disorders
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Phonetics and Phonology Research
Keywords
subglottal pressure, fundamental frequency, vocal fold adduction, vocal fold length, larynx, Alligator mississippiensis, contact calls, frequency modulation, laryngeal motor control
MeSH terms
Aging, Alligators and Crocodiles, Animals, Computer Simulation, Female, Glottis, Male, Models, Biological, Muscles, Pressure, Respiratory Physiological Phenomena, Sound Spectrography, Tomography, X-Ray Computed, Vocal Cords, Vocalization, Animal

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