Quasi-static and dynamic motions of the columellar footplate in ostrich ( Struthio camelus ) measured ex vivo

Muyshondt, Pieter G.G.; Claes, Raf; Aerts, Peter; Dirckx, Joris J.J.

doi:10.1016/j.heares.2017.11.005

Cited by 9 publications

(8 citation statements)

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“…The fine structure of the eardrum-columella complex may be an adaptation to underwater hearing but awaits comparative studies using modern high-resolution techniques such as micro-CT scanning (see e.g. Muyshondt et al, 2018).…”

Section: Potential Anatomical Adaptations For Underwater Hearingmentioning

confidence: 99%

Amphibious hearing in a diving bird, the great cormorant (Phalacrocorax carbo sinensis)

Larsen

Wahlberg

Christensen‐Dalsgaard

2020

Journal of Experimental Biology

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Diving birds can spend several minutes underwater during pursuit-dive foraging. To find and capture prey, such as fish and squid, they probably need several senses in addition to vision. Cormorants, very efficient predators of fish, have unexpectedly low visual acuity underwater. So, underwater hearing may be an important sense, as for other diving animals. We measured auditory thresholds and eardrum vibrations in air and underwater of the great cormorant (Phalacrocorax carbo sinensis). Wild-caught cormorant fledglings were anaesthetized, and their auditory brainstem response (ABR) and eardrum vibrations to clicks and tone bursts were measured, first in an anechoic box in air and then in a large water-filled tank, with their head and ears submerged 10 cm below the surface. Both the ABR waveshape and latency, as well as the ABR threshold, measured in units of sound pressure, were similar in air and water. The best average sound pressure sensitivity was found at 1 kHz, both in air (53 dB re. 20 µPa) and underwater (58 dB re. 20 µPa). When thresholds were compared in units of intensity, however, the sensitivity underwater was higher than in air. Eardrum vibration amplitude in both media reflected the ABR threshold curves. These results suggest that cormorants have in-air hearing abilities comparable to those of similar-sized diving birds, and that their underwater hearing sensitivity is at least as good as their aerial sensitivity. This, together with the morphology of the outer ear (collapsible meatus) and middle ear (thickened eardrum), suggests that cormorants may have anatomical and physiological adaptations for amphibious hearing.

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Section: Potential Anatomical Adaptations For Underwater Hearingmentioning

confidence: 99%

Amphibious hearing in a diving bird, the great cormorant (Phalacrocorax carbo sinensis)

Larsen

Wahlberg

Christensen‐Dalsgaard

2020

Journal of Experimental Biology

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“…For the annular ligament, a value of 0.145 MPa was adopted to give reasonable velocity ratios. This value was taken from literature (Muyshondt et al, 2018) and is based on the measured acoustic stiffness impedance of the annular ligament in ostrich (Muyshondt et al, 2016a). Given the data of Christensen-Dalsgaard and Manley ( 2008), maximal TM-apex velocities and corresponding resonance frequencies should be observed between 3-4.5 kHz.…”

Section: Fe Model Description 221 the Isolated Me Modelmentioning

confidence: 99%

“…In many animals (including lizards) the IE plays an important and active role in ME motion (Manley, 2017). To include IE loading in the FE model, we followed the approach from Muyshondt et al (2016aMuyshondt et al ( , 2018. The IE impedance on the medial FP surface is a complex quantity, which was described by a three-parameter model to FP piston-like motion.…”

Section: The Inner Earmentioning

confidence: 99%

“…3C). Experimental data on other species indicate that a rocking motion of the FP is present at higher frequencies (e.g., in birds (Muyshondt et al, 2018)).…”

Section: The Isolated Me Modelmentioning

confidence: 99%

“…Subsequently, we studied the coupled ME model to deduce the directionality in the anole and how the ME and interaural cavity play a role in the acoustical coupling of the TMs. Additionally, we investigated the effect of IE loading by applying a pressure load to the footplate (FP), utilizing a three-parameter model after Muyshondt et al (2016aMuyshondt et al ( , 2018.…”

Section: Introductionmentioning

confidence: 99%

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Sound localization in the lizard using internally coupled ears: A finite-element approach

2019

Self Cite

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A number of interesting differences become apparent when comparing the hearing systems of terrestrial vertebrates, especially between mammals and non-mammals. Almost all non-mammals possess only a single ossicle, enabling impedance matching and hearing below 10 kHz. The middle ear (ME) evolved as a chain of three ossicles in mammals, enabling sound transmission up to higher frequencies than in similar-sized non-mammals.The relatively low-frequency hearing in non-mammals is associated with audible wavelengths that are significantly larger than the head. Therefore, it is unlikely that localization of the sound source can be obtained by using external cues between the ears (intensity and time difference between both sides), especially when compared to similarly sized mammals. The heads of many non-mammals contain large air-filled cavities, which acoustically couple both MEs. This article studies acoustic responses and sound-source localization capabilities of the coupled MEs of the brown anole (Anolis sagrei), using finite-element modeling. Based on high-resolution μCT data, 3D finite-element models of the ME and interaural cavity were constructed. The parameter values in the ME model were determined such that the response of the isolated ME matches experimental data of literature and the velocity ratio between the tympanic membrane (apex) and footplate reflects the anatomical arrangement of the columellar lever in the anole. It was found from simulation of the coupled ME model that the interaural connection amplifies intensity differences between both sides and thus enhances the capability of sound-source localization. In addition, the interaural canal doubles the phase differences of the incident external sound waves between the eardrums. In isolated ears, generating such phase differences would require head sizes twice as large. Effects of the inner-ear loading on the sound-source localization of the coupled MEs were investigated as well. The inner-ear load lowered the peak velocity ratios between the ears, but created broader plateaus of useful directionality, indicating that innerear loading not only influences sound perception but also sound localization in internally connected ears.

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Comparative morphology of the avian bony columella

Peacock

Spellman

Field

et al. 2023

The Anatomical Record

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In birds, the columella is the only bony element of the sound conducting apparatus, conveying vibrations of the cartilaginous extracolumella to the fluid of the inner ear. Although avian columellar morphology has attracted some attention over the past century, it nonetheless remains poorly described in the literature. The few existing studies mostly focus on morphological descriptions in relatively few taxa, with no taxonomically broad surveys yet published. Here we use observations of columellae from 401 extant bird species to provide a comprehensive survey of columellar morphology in a phylogenetic context. We describe the columellae of several taxa for the first time and identify derived morphologies characterizing higher‐level clades based on current phylogenies. In particular, we identify a derived columellar morphology diagnosing a major subclade of Accipitridae. Within Suliformes, we find that Fregatidae, Sulidae, and Phalacrocoracidae share a derived morphology that is absent in Anhingidae, suggesting a secondary reversal. Phylogenetically informed comparisons allow recognition of instances of homoplasy, including the distinctive bulbous columellae in suboscine passerines and taxa belonging to Eucavitaves, and bulging footplates that appear to have evolved at least twice independently in Strigiformes. We consider phylogenetic and functional factors influencing avian columellar morphology, finding that aquatic birds possess small footplates relative to columellar length, possibly related to hearing function in aquatic habitats. By contrast, the functional significance of the distinctive bulbous basal ends of the columellae of certain arboreal landbird taxa remains elusive.

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Quasi-static and dynamic motions of the columellar footplate in ostrich ( Struthio camelus ) measured ex vivo

Cited by 9 publications

References 50 publications

Amphibious hearing in a diving bird, the great cormorant (Phalacrocorax carbo sinensis)

Amphibious hearing in a diving bird, the great cormorant (Phalacrocorax carbo sinensis)

Sound localization in the lizard using internally coupled ears: A finite-element approach

Comparative morphology of the avian bony columella

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