Air sacs and vocal fold vibration: Implications for evolution of speech

Boer, Bart de

doi:10.12775/v10235-011-0002-5

Cited by 10 publications

(9 citation statements)

References 36 publications

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“…Non-human apes have several types of air sacs, such as large laryngeal air sacs (Ybarra, 1995). The function of these air sacs are very much under debate (Boer, 2012;Hauser et al, 2002;Fitch et al, 2016). From "relatively functionless" (Harrison, 1995;Negus, 1949), or multimodal displaying (Perlman and Salmi, 2017), or avoiding over-oxygenation by "rebreathing" stored CO2 rich air that was expired earlier from the lungs, or for "vocal amplification" possibly serving exaggeration of body size (Fitch and Hauser, 2002;Hewitt et al, 2002).…”

Section: What About Other Extant Non-human Apes?mentioning

confidence: 99%

Origins of vocal-entangled gesture

Pouw¹,

Fuchs²

2021

Preprint

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Humans move their upper limbs for communicative purposes during speaking. They gesture. Such movements interact on multiple levels with speaking. In connection to what is said, gestures meaningfully shape with varying means of representation. Yet, gestures also have non-representational aspects; they quasi-rhythmically pulse with prosodic structure in speech. In explaining how modern human gesturing practices emerge in phylogeny or ontogeny, it is undisputed that gestures proliferated because they provide particularly effective means to refer to absent or distal state of affairs. It suggested that displaced or deictic reference is gestures' most basic proper function. The upshot is that the non-representational pulsing quality of gesture is completely ignored as something a) that requires an explanation or b) something that can elucidate how gesture practices emerged from more basic beginnings shared with other animals. However, recent research provides evidence for direct biomechanical interaction between pulsing manual movements and respiratory-vocal activity. We argue that this physical link is enacted during infant vocal-motor babbling - way before infants learn to represent manually. Further, we argue that gesture-vocal biomechanics directly relates to the cross-species phenomenon of locomotor-respiratory(-vocal) coupling. Given that gesture-speech biomechanics has its roots in locomotor-respiratory coupling, it can be related to bipedalism and respiratory complexification, i.e., an adaptation for the faculty of speech. We conclude that the physical origins of vocal-entangled gesture run much deeper and unfolded more gradually than currently assumed. The entanglement of sound and movement arose out of natural physical coalitions between vocal, respiratory, and limb systems that are forced to interact. We thus invert current argumentation of how gesture and vocalization must have evolved and rethink what is foundational of human gesture. This perspective underlines that a more comprehensive investigation of the physical basis of bodily communication can yield new sources of semiotic significance in human and non-human animals.

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Section: What About Other Extant Non-human Apes?mentioning

confidence: 99%

Origins of vocal-entangled gesture

Pouw¹,

Fuchs²

2021

Preprint

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“…Recent studies with both physical and computer vocal tract models suggest more specifically that human ancestors might have lost their laryngeal air sacs because of their interference with the articulation of complex vocalizations, such as in speech or singing (de Boer 2012b). Physical models show that air sacs increase the instability of vocalization by inducing nonlinear coupling between the source and filter of the vocal tract (Riede et al 2008).…”

Section: Laryngeal Air Sacs and The Evolution Of Speechmentioning

confidence: 99%

“…Physical models show that air sacs increase the instability of vocalization by inducing nonlinear coupling between the source and filter of the vocal tract (Riede et al 2008). In addition, computer models reveal that air sacs can cause changes to the resonance patterns of the vocal tract (de Boer 2009). Vocalizations take on the low frequency resonances of the air sacs, and the original resonances of the vocal tract are shifted up in frequency, which causes them to be closer together.…”

Section: Laryngeal Air Sacs and The Evolution Of Speechmentioning

confidence: 99%

“…All that remains are vestigial structures of the lateral ventricles, and only in rare pathological cases do humans have small air sacs (Stell and Maran 1975). Some researchers have proposed that this derived feature of the human vocal tract holds important clues to the evolution of speech (MacLarnon and Hewitt 1999;Fitch 2000;Fitch and Hauser 2003;de Boer 2012a). Might humans have lost their air sacs as a consequence of selection pressures arising from the evolution of the increasingly complex vocal communication that led to speech?…”

Section: Introductionmentioning

confidence: 99%

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Gorillas may use their laryngeal air sacs for whinny-type vocalizations and male display

Perlman

Salmi

2017

Journal of Language Evolution

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Great apes and siamangs-but not humans-possess laryngeal air sacs, suggesting that they were lost over hominin evolution. The absence of air sacs in humans may hold clues to speech evolution, but little is known about their functions in extant apes. We investigated whether gorillas use their air sacs to produce the staccato 'growling' of the silverback chest beat display. This hypothesis was formulated after viewing a nature documentary showing a display by a silverback western gorilla (Kingo). As Kingo growls, the video shows distinctive vibrations in his chest and throat under which the air sacs extend. We also investigated whether other similarly staccato vocalizations-the whinny, sex whinny, and copulation grunt-might also involve the air sacs. To examine these hypotheses, we collected an opportunistic sample of video and audio evidence from research records and another documentary of Kingo's group, and from videos of other gorillas found on YouTube. Analysis shows that the four vocalizations are each emitted in rapid pulses of a similar frequency (8-16 pulses per second), and limited visual evidence indicates that they may all occur with upper torso vibrations. Future research should determine how consistently the vibrations co-occur with the vocalizations, whether they are synchronized, and their precise location and timing. Our findings fit with the hypothesis that apes-especially, but not exclusively males-use their air sacs for vocalizations and displays related to size exaggeration for sex and territory. Thus changes in social structure, mating, and sexual dimorphism might have led to the obsolescence of the air sacs and their loss in hominin evolution.

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“…In systems where source and filter cannot behave independently, the set of signals that can be produced is necessarily more limited. This consequence is demonstrated in a modeling study showing that when source and filter are closely coupled, vocalization may be more chaotic, and thus it may be more difficult to time the onset of vocalization precisely (de Boer 2012). Given these observations, it may not just be a lack of neural control that makes precise vocalizations difficult for nonhuman primates.…”

mentioning

confidence: 99%