Sound transmission by the hyoid apparatus during echolocation in bats Chelsie C.G. Snipes1 and Richard T. Carter1 1 East Tennessee State University, Johnson City TN, USA The morphology of the stylohyal-tympanic bone articulation found in laryngeally echolocating bats is highly indicative of a function associated with signal production. One untested hypothesis is that this morphology allows the transfer of a sound signal from the larynx to the tympanic bones (auditory bulla) via the hyoid apparatus during signal production by the larynx. To test this hypothesis, we used µCT data, CAD editing software, and finite element analysis (FEA) to model the propagation of sound through the hyoid chain into the tympanic bones. This involved making digital segmentations from the µCT data of the tympanic bones and cartilaginous segments and converting it into a digital mesh body. Since the cartilaginous segments are not visible in CTs, we segmented the air in each gap and subsequently used a Boolean function in CAD software to fit each bony end into their respective cartilaginous segment. Further post-processing of the model included a reduction in the number of facets bodies and smoothing surfaces which allowed us to convert it into a solid body model. The solid body geometry was then uploaded into FEA software and assigned material properties for cortical bone, cartilage, and bulla. Additional biomechanical data, including Young’s Modulus, Poisson’s ratio, and speed of sound through each material were defined in previous literature. We ran two FEA analysis with our model: the first was an acoustic analysis that modelled sound propagation through our material (bone and cartilage), and the second was a coupled modal and structural analysis that modelled resonant behavior and sound pressure wave propagation from the hyoid body to the tympanic bones. Our models support the hypothesis that bats use this physical connection between the larynx and auditory bulla to transfer sound (mechanical excitation). Our models show both pressure waves and vibration due to resonance could be used to transfer this signal and this resonance behavior can be modulated by restraining the hyoid apparatus, perhaps through muscle contraction. We propose that by modulating the resonant behavior of the hyoid apparatus, bats can selectively filter which frequencies of sound are transferred from the larynx to the auditory bulla during echolocation signal production.

Made available in DSpace on 2017-07-21T19:59:51Z (GMT). No. of bitstreams: 1 Debora Kremer.pdf: 14046680 bytes, checksum: d4d54e7a64612cdc40e86b5171443c46 (MD5) Previous issue date: 2011-05-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Tillandsia L. is the largest genus of the subfamily Tillandsioideae (Bromeliaceae) with ca. 557 species. It is distributed from the southern U. S. A to central Argentina and Chile. Traditionally the genus has been divided into seven subgenera: Tillandsia subg. Allardtia (A. Dietrich) Baker, Tillandsia subg. Anoplophytum (Beer) Baker, Tillandsia subg. Phytarrhiza (Vis.) Baker, Tillandsia subg. Diaphoranthema (Beer) Baker, Tillandsia subg. Tillandsia L., Tillandsia subg. Pseudalcantarea Mez and Tillandsia subg. Pseudo-Catopsis Baker. The taxonomic study of the species Tillandsia in the Paraná state was presented. Were found 17 species in 4 subgenera:Tillandsia subg. Diaphoranthema -Tillandsia loliacea Mart. ex Schult. & Schult.f., Tillandsia recurvata (L.) L, Tillandsia tricholepis Baker and Tillandsia usneoides (L.) L.; Tillandsia subg. Anoplophytum -Tillandsia didisticha (E. Morren) Baker, Tillandsia gardneri Lindley, Tillandsia geminiflora Brong., Tillandsia lineares Vell., Tillandsia lorentziana Griseb.; Tillandsia pohliana Mez, Tillandsia recurvifolia Hooker, Tillandsia stricta Solander, Tillandsia tenuifolia L.; Tillandsia subg. Phytarrhiza - Tillandsia crocata (E. Morren) Baker, Tillandsia streptocarpa Baker; Tillandsia mallemontii Glazou ex Mez e Tillandsia subg. Tillandsia -Tillandsia polystachia (L.) L.. Identification Keys, as well as descriptions, illustrations, comments and distribuition patterns are presented. The results show that the Paraná has a high species richness when compared to neighboring states. Besides the taxonomic study, there were some evolutionary adaptations of species, fitting them in ecophysiological types proposed in the literature. Only T. polystachia presents wide rosette forming tank. The remaining species are characterized by the absence of the tank, the presence or absence of non-root in adulthood and four species were found to be minimized. / Tillandsia L. é o maior gênero da subfamília Tillandsioideae (Bromeliaceae) com 557 espécies, distribuídas desde o sul dos Estados Unidos até a Argentina e o Chile. Tradicionalmente, está dividido em sete subgêneros: Tillandsia subg. Allardtia (A. Dietrich) Baker, Tillandsia subg. Anoplophytum (Beer) Baker, Tillandsia subg. Phytarrhiza (Vis.) Baker, Tillandsia subg. Diaphoranthema (Beer) Baker, Tillandsia subg. Tillandsia L., Tillandsia subg. Pseudalcantarea Mez e Tillandsia subg. Pseudo- Catopsis Baker. Um estudo taxonômico de Tillandsia no Estado do Paraná foi realizado e foram encontrados 17 táxons, distribuídos em 4 subgêneros: Tillandsia subg. Diaphoranthema -Tillandsia loliacea Mart. ex Schult. & Schult.f., Tillandsia recurvata (L.) L, Tillandsia tricholepis Baker e Tillandsia usneoides (L.) L.; Tillandsia subg. Anoplophytum - Tillandsia didisticha (E. Morren) Baker, Tillandsia gardneri Lindley, Tillandsia geminiflora Brong., Tillandsia lineares Vell., Tillandsia lorentziana Griseb.; Tillandsia pohliana Mez, Tillandsia recurvifolia Hooker, Tillandsia stricta Solander, Tillandsia tenuifolia L.; Tillandsia subg. Phytarrhiza - Tillandsia crocata (E. Morren) Baker, Tillandsia streptocarpa Baker; Tillandsia mallemontii Glazou ex Mez e Tillandsia subg. Tillandsia – com apenas uma espécie Tillandsia polystachia (L.) L.. São apresentadas chaves de identificação, descrições, comentários,ilustrações e distribuição geográfica de cada táxon. Os resultados revelaram que a riqueza de espécies de Tillandsia no Paraná é maior quando comparada aos Estados vizinhos. Além do estudo taxonômico, foram observadas algumas adaptações evolutivas das espécies, enquadrando-as nos tipos ecofisiológicos propostos em literatura. Apenas T. polystachia apresenta roseta ampla formando tanque. As demais espécies são caracterizadas pela ausência de tanque, a presença ou não de raiz na fase adulta e quatro delas, foram consideradas espécies minimizadas.