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Homo Sapiens (“Us”): Strengths and Weaknesses
Published in Michael Hehenberger, Zhi Xia, Huanming Yang, Our Animal Connection, 2020
Michael Hehenberger, Zhi Xia, Huanming Yang
Sound waves are reflected and attenuated when they hit the cartilage (“pinna”) surrounding the ear canal. The resulting anatomical changes provide information that will help the brain determine the direction from which the sounds came. Sound waves travel through the ear canal, hit the eardrum and move across the air-filled middle ear cavity via a series of delicate bones or “ossicles”: as illustrated in Fig. 4.11, the three ossicles malleus (hammer), incus (anvil), and stapes (stirrup) convert the lower-pressure eardrum sound vibrations into higher-pressure sound vibrations at another, smaller membrane called the oval window or vestibular window.
Human Hearing and Noise Criteria
Published in David A. Bies, Colin H. Hansen, Carl Q. Howard, Engineering Noise Control, 2018
David A. Bies, Colin H. Hansen, Carl Q. Howard
Sound enters the ear through the auditory duct (or ear canal), a more or less straight tube between 23 and 30 mm in length, at the end of which is the eardrum, a diaphragm-like structure known as the tympanic membrane. Sound entering the ear causes the eardrum to move in response to acoustic pressure fluctuations within the auditory canal and to transmit motion through a mechanical linkage provided by three tiny bones, called ossicles, to a second membrane at the oval window of the middle ear. Sound is transmitted through the oval window to the inner ear (see Figure 2.1).
The Human Ear
Published in David A. Bies, Colin H. Hansen, Engineering Noise Control, 2017
David A. Bies, Colin H. Hansen
Sound enters the ear through the auditory duct, a more or less straight tube between 23 and 30 mm in length, at the end of which is the eardrum, a diaphragm-like structure known as the tympanic membrane. Sound entering the ear causes the eardrum to move in response to acoustic pressure fluctuations within the auditory canal and to transmit motion through a mechanical linkage provided by three tiny bones, called ossicles, to a second membrane at the oval window of the middle ear. Sound is transmitted through the oval window to the inner ear (see Figure 2.1).
Design of a resilient ring for middle ear’s chamber stapes prosthesis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2018
Emilia Anna Kiryk, Konrad Kamieniecki, Monika Kwacz
Stapes prostheses are used for surgical treatment of otosclerosis, which is an illness affecting auditory ossicles located in the middle ear. The ossicles (malleus, incus and stapes) link the outer and inner ear and transmit sound vibrations from the tympanic membrane to the oval window (OW). The stapes footplate (SF) is suspended on a highly elastic annular ligament (AL) in the OW niche. The AL enables the stapes to vibrate and to generate a pressure wave in the perilymph fluid. Otosclerosis immobilizes the stapes due to stiffening of the AL. This leads to a decrease in stimulation of the perilymph and manifests by conductive hearing loss (CHL). Otosclerosis is the cause of almost 22% of all CHL (Potocka et al. 2010).
Semi-automatic 3D reconstruction of middle and inner ear structures using CBCT
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Florian Beguet, Thierry Cresson, Mathieu Schmittbuhl, Cédric Doucet, David Camirand, Philippe Harris, Jean-Luc Mari, Jacques de Guise
To obtain precise modelling of the structures of the inner and middle ear, a segmentation step is necessary to extract and label these structures from CBCT images. The segmentation step is challenging (Beucher and Lantuéjoul 1979; Kass et al. 1988; Osher and Sethian 1988; Yoo et al. 2000, 2001; Pohle and Toennies 2001; Xianfen et al. 2005; Noble et al. 2009, 2011; Bradshaw et al. 2010; Poznyakovskiy et al. 2013; Cerrolaza et al. 2014; Ruiz Pujadas et al. 2016; Zhu et al. 2017) especially because these structures are linked together, as illustrated by the 3D models in the Figure 1d. The structures of the middle ear are characterised by the same bone nature but a variable bone density (Greef et al. 2015), demonstrating a certain range of intensities in CBCT imaging. The depiction of the border of these structures can thus be very challenging, especially for the incudomalleolar joint (blue arrow in Figure 1b) and the suspensory ligaments of the ossicular chain (cyan arrow in Figure 1b). The middle ear is not a completely closed structure, as it presents two windows: the round window sealed by the secondary tympanic membrane; and the oval window, which is in direct contact with the stapes (green arrows in Figure 1a–c). Moreover, the vestibulocochlear nerve emerging directly from the inner ear presents quite the same level of density as the chamber of the vestibule and the spirally coiled cochlea (red arrows in Figure 1a). In addition, the segmentation of these very small and complex structures presents some specific challenges: The shape of the inner ear is topologically complex: the cochlea is a snail-shaped object and the semi-circular canals correspond to 3D objects characterized by a surface of genus 3 (Figure 1a). The preservation of these complex features during the process of segmentation of the inner ear remains a difficult challenge.The stapes is a very fine structure of genus 1, and it is 3 mm wide and 4 mm high with a diameter of approximately 0.4 mm for the crus (Figure 1c) (Farahani and Nooranipour 2008). This creates great difficulties for the depiction of its limits considering that the spatial resolution of the CBCT images is 0.15 mm; only its curvature is indeed detectable at the interface of the oval window(green arrow in Figure 1a–c).