The hyoid as a sound conducting apparatus in laryngeally echolocating bats

Snipes, Chelsie C. G.; Carter, Richard T.

doi:10.1111/joa.13615

Cited by 5 publications

(23 citation statements)

References 25 publications

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“…We ran a series of harmonic response analyses using modal superposition within ANSYS. Material properties for bone, cartilage, the tympanic annulus, and the TM were assumed to be isotropically elastic ( Dumont et al 2005 ; Snipes and Carter 2022 ). Bone, cartilage, the tympanic annulus, and the TM were assigned material properties taken from the literature ( Currey 2006 ; Caminos et al 2018 ) ( Table 2 ).…”

Section: Methodsmentioning

confidence: 99%

“…In that study, we modeled varying levels of constraint (0, 1, 3, and 5 fixed points) on the basihyal to evaluate the effect of muscle attachments and found differences in the performance of our R. pusillus and A. jamaicensis models. As basihyal constraint was increased, the displacement of the bulla in the A. jamaicensis model quickly dropped below the assigned threshold of 2.9e-11 m; and conversely, the bulla of the R. pusillus model exhibited displacement peaks above the assigned threshold at all levels of constraint ( Snipes and Carter 2022 ). These results lead us to consider whether HDC echolocators could use vibration of the bulla and bone conduction to transfer sound into the inner ear.…”

Section: Introductionmentioning

confidence: 99%

“…Finite-element (FE) modeling of this connection between larynx and ear indicates that sound can be effectively transmitted from the laryngeal surface of the hyoid to the auditory bullae in Artibeus jamaicensis (a low duty cycle [LDC]/frequency modulated [FM] echolocator) and Rhinolophus pusillus (a high duty cycle [HDC]/narrow band [NB] echolocator) ( Snipes and Carter 2022 ). Here, duty cycle refers to the length of time in a call sequence in which there is out going sound, where LDC bats use 10% of the call sequence and HDC bats use more than 50% of each sequence ( Fenton et al 2012 ).…”

Section: Introductionmentioning

confidence: 99%

“…2 ). Snipes and Carter (2022) did not include a tympanic membrane (TM) in their FE models but instead used the vibration of the bulla as evidence that sound likely moved into the inner ear via bone conduction or a rocking motion of the bulla/TM unit in the lateral-medial plane, which presumably sets the ear ossicles into motion. In that study, we modeled varying levels of constraint (0, 1, 3, and 5 fixed points) on the basihyal to evaluate the effect of muscle attachments and found differences in the performance of our R. pusillus and A. jamaicensis models.…”

Section: Introductionmentioning

confidence: 99%

“…These results lead us to consider whether HDC echolocators could use vibration of the bulla and bone conduction to transfer sound into the inner ear. The relatively poor performance of the constrained A. jamaicensis model ( Snipes and Carter 2022 ), and the placement of the spatulate end of the stylohyal on the bulla ( Fig. 2 ) may mean that excitation of the TM (similar to what airborne sound would do) is the most efficient route for hyoid-borne sound to reach the inner ear in LDC bats.…”

Section: Introductionmentioning

confidence: 99%

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Vibroacoustic Response of the Tympanic Membrane to Hyoid-Borne Sound Generated during Echolocation in Bats

Snipes

Carter

2023

Integrative Organismal Biology

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The hyoid apparatus in laryngeally echolocating bats is unique as it forms a mechanical connection between the larynx and auditory bullae which has been hypothesized to transfer the outgoing echolocation call to the middle ear during call emission. Previous finite element modeling (FEM) found that hyoid-borne sound can reach the bulla at an amplitude likely heard by echolocating bats; however, that study did not model how or if the signal could reach the inner ear (or cochlea). One route that sound could take is via stimulation of the eardrum – similarly to that of air-conducted sound. We used µCT data to build models of the hyoid apparatus and middle ear from six species of bats with variable morphology. Using FEM, we ran harmonic response analyses to measure the vibroacoustic response of the tympanic membrane due to hyoid-borne sound generated during echolocation and found that hyoid-borne sound in all six species stimulated the eardrum within a range likely heard by bats. Although there was variation in the efficiency between models, there are no obvious morphological patterns to account for it. This suggests that hyoid morphology in laryngeal echolocators is likely driven by other associated functions.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Vibroacoustic Response of the Tympanic Membrane to Hyoid-Borne Sound Generated during Echolocation in Bats

Snipes

Carter

2023

Integrative Organismal Biology

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The vocal apparatus: An understudied tool to reconstruct the evolutionary history of echolocation in bats?

et al. 2023

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Laryngeal echolocation in bats could have evolved following two scenarios: a single origin from a common ancestor or an independent acquisition inside the two clades Yinpterochiroptera and Yangochiroptera. Later, some members of Yinpterochiroptera possibly lost their ability to echolocate. In bats, the larynx produces vocalizations for communication and, in most species, for echolocation. Here, we describe how comparative chiropteran laryngeal morphology is a novel area of research that could improve the understanding of echolocation and may help resolve the evolutionary history of bats. This review provides morphological descriptions and comparisons of the bat larynx and bioacoustics interpretations. We discuss the importance of understanding: (1) laryngeal sound production so it may be linked with the evolution of the chiropteran auditory system; and (2) the evolution of laryngeal morphology to understand the ecological and behavioural aspects of bat biology. We find that a strong phylogenetic signal is potentially the main source explaining macroevolutionary variation in laryngeal form among bats. We predict that the three parameters of sound production in echolocation (frequency, intensity, and rate of calls) are independently modulated by different laryngeal components, but this hypothesis remains understudied in terms of species diversity.

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Development of the hyolaryngeal architecture in horseshoe bats: insights into the evolution of the pulse generation for laryngeal echolocation

Nojiri,

Takechi,

Furutera

et al. 2024

EvoDevo

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Background The hyolaryngeal apparatus generates biosonar pulses in the laryngeally echolocating bats. The cartilage and muscles comprising the hyolarynx of laryngeally echolocating bats are morphologically modified compared to those of non-bat mammals, as represented by the hypertrophied intrinsic laryngeal muscle. Despite its crucial contribution to laryngeal echolocation, how the development of the hyolarynx in bats differs from that of other mammals is poorly documented. The genus Rhinolophus is one of the most sophisticated laryngeal echolocators, with the highest pulse frequency in bats. The present study provides the first detailed description of the three-dimensional anatomy and development of the skeleton, cartilage, muscle, and innervation patterns of the hyolaryngeal apparatus in two species of rhinolophid bats using micro-computed tomography images and serial tissue sections and compares them with those of laboratory mice. Furthermore, we measured the peak frequency of the echolocation pulse in active juvenile and adult individuals to correspond to echolocation pulses with hyolaryngeal morphology at each postnatal stage. Results We found that the sagittal crests of the cricoid cartilage separated the dorsal cricoarytenoid muscle in horseshoe bats, indicating that this unique morphology may be required to reinforce the repeated closure movement of the glottis during biosonar pulse emission. We also found that the cricothyroid muscle is ventrally hypertrophied throughout ontogeny, and that the cranial laryngeal nerve has a novel branch supplying the hypertrophied region of this muscle. Our bioacoustic analyses revealed that the peak frequency shows negative allometry against skull growth, and that the volumetric growth of all laryngeal cartilages is correlated with the pulse peak frequency. Conclusions The unique patterns of muscle and innervation revealed in this study appear to have been obtained concomitantly with the acquisition of tracheal chambers in rhinolophids and hipposiderids, improving sound intensity during laryngeal echolocation. In addition, significant protrusion of the sagittal crest of the cricoid cartilage and the separated dorsal cricoarytenoid muscle may contribute to the sophisticated biosonar in this laryngeally echolocating lineage. Furthermore, our bioacoustic data suggested that the mineralization of these cartilages underpins the ontogeny of echolocation pulse generation. The results of the present study provide crucial insights into how the anatomy and development of the hyolaryngeal apparatus shape the acoustic diversity in bats.

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The hyoid as a sound conducting apparatus in laryngeally echolocating bats

Cited by 5 publications

References 25 publications

Vibroacoustic Response of the Tympanic Membrane to Hyoid-Borne Sound Generated during Echolocation in Bats

Vibroacoustic Response of the Tympanic Membrane to Hyoid-Borne Sound Generated during Echolocation in Bats

The vocal apparatus: An understudied tool to reconstruct the evolutionary history of echolocation in bats?

Development of the hyolaryngeal architecture in horseshoe bats: insights into the evolution of the pulse generation for laryngeal echolocation

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