Anatomy Of Ear Research Articles

The Utility of a Predictive Model for Cochlear Implant Operating Time.

This study analyzes multiple factors and their significance in determining the operative timing for cochlear implants at one institution over a 10-year period. Retrospective case review. Tertiary referral center. All patients including both adult and pediatric undergoing cochlear implantation from 2002 through January 2012. Cochlear implantation. The overall operative room time and surgical duration for patients undergoing cochlear implantation. Individual factors analyzed for influence on timing included center experience, surgeon experience, location (main OR, children's OR, outpatient OR), patient age, patient sex, bilaterality, anatomical consideration, complications, and the involvement of residents and fellows. ANOVA analysis of individual factors. Factors associated with increased surgical duration included bilateral implants, abnormal inner ear anatomy, and intraoperative complications. Factors associated with time outside the operation included surgical duration, the surgical suite type, and the availability of a fellow. Total operating room time was significantly reduced in an outpatient setting and in quicker performed procedures. The influence of factors affecting both surgical duration and time in the operating room can be predicted and used to provide more accurate estimates of operating room time.

Digital reconstruction of the inner ear of Leptictidium auderiense (Leptictida, Mammalia) and North American leptictids reveals new insight into leptictidan locomotor agility

Leptictida are basal Paleocene to Oligocene eutherians from Europe and North America comprising species with highly specialized postcranial features including elongated hind limbs. Among them, the European Leptictidium was probably a bipedal runner or jumper. Because the semicircular canals of the inner ear are involved in detecting angular acceleration of the head, their morphometry can be used as a proxy to elucidate the agility in fossil mammals. Here we provide the first insight into inner ear anatomy and morphometry of Leptictida based on high-resolution computed tomography of a new specimen of Leptictidium auderiense from the middle Eocene Messel Pit (Germany) and specimens of the North American Leptictis and Palaeictops. The general morphology of the bony labyrinth reveals several plesiomorphic mammalian features, such as a secondary crus commune. Leptictidium is derived from the leptictidan groundplan in lacking the secondary bony lamina and having proportionally larger semicircular canals than the leptictids under study. Our estimations reveal that Leptictidium was a very agile animal with agility score values (4.6 and 5.5, respectively) comparable to Macroscelidea and extant bipedal saltatory placentals. Leptictis and Palaeictops have lower agility scores (3.4 to 4.1), which correspond to the more generalized types of locomotion (e.g., terrestrial, cursorial) of most extant mammals. In contrast, the angular velocity magnitude predicted from semicircular canal angles supports a conflicting pattern of agility among leptictidans, but the significance of these differences might be challenged when more is known about intraspecific variation and the pattern of semicircular canal angles in non-primate mammals.

Investigation of middle ear anatomy and function with combined video otoscopy-phase sensitive OCT.

We report the development of a novel otoscopy probe for assessing middle ear anatomy and function. Video imaging and phase-sensitive optical coherence tomography are combined within the same optical path. A sound stimuli channel is incorporated as well to study middle ear function. Thus, besides visualizing the morphology of the middle ear, the vibration amplitude and frequency of the eardrum and ossicles are retrieved as well. Preliminary testing on cadaveric human temporal bone models has demonstrated the capability of this instrument for retrieving middle ear anatomy with micron scale resolution, as well as the vibration of the tympanic membrane and ossicles with sub-nm resolution.

Methods to study the development, anatomy, and function of the zebrafish inner ear across the life course.

The inner ear is a remarkably intricate structure able to detect sound, motion, and gravity. During development of the zebrafish embryo, the ear undergoes dynamic morphogenesis from a simple epithelial vesicle into a complex labyrinth, consisting of three semicircular canals and three otolithic sensory organs, each with an array of differentiated cell types. This microcosm of biology has led to advances in understanding molecular and cellular changes in epithelial patterning and morphogenesis, through to mechanisms of mechanosensory transduction and the origins of reflexive behavior. In this chapter, we describe different methods to study the zebrafish ear, including high-speed imaging of otic cilia, confocal microscopy, and light-sheet fluorescent microscopy. Many dyes, antibodies, and transgenic lines for labeling the ear are available, and we provide a comprehensive review of these resources. The developing ear is amenable to genetic, chemical, and physical manipulations, including injection and transplantation. Chemical modulation of developmental signaling pathways has paved the way for zebrafish to be widely used in drug discovery. We describe two chemical screens with relevance to the ear: a fluorescent-based screen for compounds that protect against ototoxicity, and an in situ-based screen for modulators of a signaling pathway involved in semicircular canal development. We also describe methods for dissection and imaging of the adult otic epithelia. We review both manual and automated methods to test the function of the inner ear and lateral line, defects in which can lead to altered locomotor behavior. Finally, we review a collection of zebrafish models that are generating new insights into human deafness and vestibular disorders.

Endoscopic Ear Surgery: Critical Review of Anatomy and Physiology of Normal and Reconstructive Middle Ear.

Middle ear anatomy is complex hence it is difficult to study the microscopic vibration of tympanic membrane and ossicles. The basic research has been done in few centres. Our experience is based on clinical data. The lack of quantitative understanding of structural and functional relationship in the mechanical response of the normal and reconstructed middle ear is major factor in poor hearing results after surgery (Merchant et al. in J Laryngol Otol 112:715-731, 1998). The vibration pattern of tympanic membrane changes with different frequencies. It depends upon shape, position and tension of tympanic membrane. Sometimes reconstructed tympanic membrane loses its shape and tension and thus its vibratory response (Pusalkar and Steinbach in Transplants and implants in otology II, 1992). Then what should be the shape, position, tension of the tympanic membrane and the ossicles. In order to have a serviceable hearing, dry and safe ear, there is a necessity of answering all these queries by us.

Treatment of Prominent Ears and Otoplasty: A Contemporary Review.

Prominent ears affect approximately 5% of the population and can have a significant psychological impact on patients. A wide variety of otoplasty techniques have been described, all sharing the goal of re-creating the normal appearance of the ear and achieving symmetry between the 2 sides. Recent trends in otoplasty techniques have consistently moved toward less invasive options, ranging from nonsurgical newborn ear molding to cartilage-sparing surgical techniques and even incisionless, office-based procedures. Herein, we review anatomy of the external ear, patient evaluation, the evolution of nonsurgical and surgical otoplasty techniques, otoplasty outcomes, and future trends for treatment of prominent ears.

Endoscopic Middle Ear Anatomy

The anatomy of the middle ear is very complex. The otologist must have a good knowledge of the structures comprising the tympanic cavity; a clear view of all the subsites of this region is essential to ensure the complete removal of all pathology. The development of endoscopic techniques to access the middle ear has offered the possibility to “look around corners” and explore hidden recesses the microscope cannot reach. Moreover, by leading to a better understanding of the different ventilation pathways of the tympanic cavity, alterations of which may cause pathologies such as cholesteatoma, endoscopy represents a surgical approach aimed toward restoring normal physiology as well as eradicating disease. In this article, we discuss the state of the art of middle ear endoscopic anatomy, describing the different subsites of this small but challenging region.

Surgical anatomy and pathology of the middle ear.

Middle ear surgery is strongly influenced by anatomical and functional characteristics of the middle ear. The complex anatomy means a challenge for the otosurgeon who moves between preservation or improvement of highly important functions (hearing, balance, facial motion) and eradication of diseases. Of these, perforations of the tympanic membrane, chronic otitis media, tympanosclerosis and cholesteatoma are encountered most often in clinical practice. Modern techniques for reconstruction of the ossicular chain aim for best possible hearing improvement using delicate alloplastic titanium prostheses, but a number of prosthesis-unrelated factors work against this intent. Surgery is always individualized to the case and there is no one-fits-all strategy. Above all, both middle ear diseases and surgery can be associated with a number of complications; the most important ones being hearing deterioration or deafness, dizziness, facial palsy and life-threatening intracranial complications. To minimize risks, a solid knowledge of and respect for neurootologic structures is essential for an otosurgeon who must train him- or herself intensively on temporal bones before performing surgery on a patient.

Radiología del oído externo: indicaciones, anatomía normal y procesos patológicos

The external ear is accessible to direct examination; the clinical history and otoscopy are sufficient to diagnose and treat most diseases of the external ear. We aim to describe the normal anatomy of the external ear, specify the indications for imaging tests, and review the clinical and radiological manifestations of the most common diseases affecting the external ear. We classify these diseases according to their origin into congenital, inflammatory, infectious, or traumatic disease or benign bone tumors or malignant tumors.Imaging does not play an important role in diseases of the external ear, but in certain clinical scenarios it can be crucial for reaching a concrete diagnosis and establishing the best treatment. Computed tomography is the first-choice technique for most diseases. Magnetic resonance imaging complements computed tomography and makes it possible to differentiate among different tissue types and to evaluate the extension of disease accurately.

The effect of seismic waterguns on the inner ears of round goby

Abstract High-pressure acoustic sources, such as seismic exploration technology or sonar, can temporarily or permanently affect the auditory system of some fish species. The majority of studies done on fish hearing aim to determine safe acoustic operating thresholds for different fishes in order to mitigate possible negative effects of these anthropogenic noise sources. In contrast, the present study was designed to evaluate the effects of a hydraulic watergun on invasive round goby in Lake Michigan as a potential population suppression tool to protect critical spawning habitat for native fishes. The goal of the present study was to evaluate the potential sub-lethal effects of pulse pressure sound technology on the hearing end organs of round goby. Round goby from Little Traverse Bay near Charlevoix, MI were exposed to 6 discharges from a seismic watergun at an average peak sound pressure level of 229 dB re 1 μPa. Fish were monitored for 60 h post-exposure and assessed for damage to otoliths and inner ear sensory hair cells. We found no significant hair cell loss or otolith damage, suggesting that a higher peak pressure level or longer duration of discharges are needed to cause significant damage to round goby inner ear anatomy.

Regulatory and funding strategies to develop a safety study of an auditory brainstem implant in young children who are deaf.

In the US, a child born deaf with abnormal inner ear anatomy and for whom a cochlear implant fails to provide benefit has no approved surgical treatment options. The auditory brainstem implant (ABI) was developed in the US for patients with Neurofibromatosis 2. A European surgical team has advanced ABI use in young children, with promising outcomes. Clinical teams face a number of challenges, from regulatory issues to funding. The strategic decisions leading to the safety and early efficacy protocol of the ABI for young children with congenital deafness are described. A sponsor-investigator pre–Investigational Device Exemption (IDE) was significantly altered in discussion with the Food and Drug Administration (FDA), followed by approval of a revised protocol. A critical step involved securing external funding through an NIH U01 clinical trial grant, and enrollment began in 2014. The protocol focused on strict inclusion criteria, clear stopping rules, and rigorous interim safety data review before proceeding with enrollment. To date, 4 of the 7 enrolled subjects met criteria for implantation. A single expected serious adverse event occurred, which resolved completely without sequela. Promising innovative treatments face a number of obstacles along the pathway to full commercialization. A strategy that included early conversations with the FDA and the device manufacturer, and successfully obtaining external funding, resulted in an approved IDE protocol. Early results indicated that the risks, though not minimal, can be successfully mitigated. These young children appear to benefit audiologically from the ABI.

Indications of cone beam CT in head and neck imaging

Conclusion: Cone Beam Computed Tomography (CBCT) can be widely used in imaging of bony structures of the anterior and lateral skull base. Significant differences of applied dosages result from the different protocols of the various indications. Objectives: CBCT is increasingly being used in head and neck imaging. Until now, no precise knowledge about its dedicated usage existed. Methods: All CBCT of 2012 and 2013 were analysed with regard to the technical parameters, the performance, and the indication for imaging. Results: In total, 1862 patients were examined in 2012 and 2013. The top eight indications of the anterior skull were (1) chronic rhinosinusitis with disturbed nasal breathing (30.3%); (2) chronic rhinosinusitis (17.6%); (3) midfacial traumatology (13.7%); (4) disturbed nasal breathing (12.8%); (5) acute rhinosinusitis (7.9%); (6) polyposis nasi (6.3%); (7) search for focus (3.9%); and (8) persistent rhinorrhea (1.2%). For the lateral skull base, the top eight were (1) control after cochlear implantation (28.4%); (2) cholesteatoma (19.7%); (3) visualization of ear anatomy (8.7%); (4) chronic otitis media mesotympanalis (6.3%); (5) conductive hearing loss (5.1%); (6) suspected mastoiditis (4.8%); (7) pathology of external auditory canal (4.8%); and (8) otosclerosis (3.3%). Applied dosage for the anterior skull base was significantly lower than for the lateral skull base (2.90 mGy vs 5.92 mGy, p < 0.05); 2.4% and 3.6% of patients’ images, respectively, had to be repeated.

Mastoid Obliteration with Autologous Bone in Mastoidectomy Canal Wall Down Surgery: a Literature Overview.

Introduction The objectives of mastoidectomy in cholesteatoma are a disease-free and dry ear, the prevention of recurrent disease, and the maintenance of hearing or the possibility to reconstruct an affected hearing mechanism. Canal wall down mastoidectomy has been traditionally used to achieve those goals with greater or lesser degrees of success. However, canal wall down is an aggressive approach, as it involves creating an open cavity and changing the anatomy and physiology of the middle ear and mastoid. A canal wall up technique eliminates the need to destroy the middle ear and mastoid, but is associated with a higher rate of residual cholesteatoma. The obliteration technics arise as an effort to avoid the disadvantages of both techniques. Objectives Evaluate the effectiveness of the mastoid obliteration with autologous bone in mastoidectomy surgery with canal wall down for chronic otitis, with or without cholesteatoma. Data Synthesis We analyzed nine studies of case series comprehending similar surgery techniques on 1017 total cases of operated ears in both adults and children, with at least 12 months follow-up. Conclusion Mastoid Obliteration with autologous bone has been utilized for many years to present date, and it seems to be safe, low-cost, with low recurrence rates - similar to traditional canal wall down procedures and with greater water resistance and quality of life improvements.

Brachio-Oto-Renal Syndrome: CT Imaging and Intraoperative Diagnostic Findings.

Branchio-oto-renal syndrome (BOR) is an autosomal dominant mutation of the EYA1 and the more recently discovered the SIX1 gene.1 The phenotype and syndrome were comprehensively described by Melnick in 1975 to include hearing loss, auricular malformations, branchial arch remnants, and renal anomalies.2 The diagnosis of BOR is made using major and minor criteria as defined by Chang et al 2004.3 However, 60% of patients who meet phenotypic criteria do not have an identifiable mutation in the EYA1 gene, leading to recent interest in the EYA-SIX regulatory system.1 The most common manifestations include hearing loss (98.5%), preauricular pits (83.6%), branchial anomalies (68.5%), renal anomalies (38.2%), and external ear abnormalities (31.5%). In terms of the imaging characteristics, the most sensitive modality remains CT of the temporal bones. The most commonly reported anomalies on temporal bone imaging include but are not limited to 1)hypoplastic apical turn of the cochlea, 2) facial nerve deviated to the medial side of the cochlea, 3) funnel-shaped internal auditory canal, and 4) patulous eustachian tube. 4 The spectrum of hearing loss in BOR is variable but most commonly presents with mixed hearing loss (50%), pure sensorineural hearing loss (25%) and pure conductive hearing loss (25%) 5. The conductive component of the hearing loss is most often the result of ossicular chain abnormalities. A 42 year old male previously diagnosed with BOR using clinical criteria presented with a conductive hearing loss. His physical exam demonstrated small external auditory canals with a normal tympanic membrane. His audiogram demonstrated a mild left sensorineural hearing loss and a maximal conductive hearing loss in the right ear. Imaging with CT revealed several findings consisted with BOR: Bilateral enlarged air-filled eustachian tubes extending from the middle ear to the nasopharynx, a widened and flared internal acoustic meatus with the nervus intermedius extending into a funnel shaped labyrinthine segment of the temporal bone and hypo-plastic horizontal canal, hypo-plastic vestibular system/epitympanum, and lateral position of the facial nerve. The incus and malleus were malformed and fixed in the attic (Fig. 1). Figure 1 Computed tomography (CT) images. Panel A: Axial view of the head demonstrating enlarged eustachian tubes (arrow). Panel B: Axial view of right internal auditory (IAC) canal demonstrating hypoplastic horizontal semicircular canal(H), and funnel shaped ... Despite the findings on CT, the patient elected to pursue a middle ear exploration prior to pursuing other rehabilitative options. At surgery, middle ear exploration revealed a very small oval window niche with no clear oval window, or stapes footplate as shown on this view with a 30° endoscope (Fig. 2). The round window niche was visible. A dehiscent facial nerve was visible at the horizontal segment. Because no mobile footplate was found there was no attempt at ossiculoplasty. The patient recovered from surgery with no change in his hearing and later went on to a Baha which he found beneficial. Figure 2 Right middle ear as viewed through a 30° endoscope during surgery. There was no clear stapes footplate, but a narrow oval window (OW) niche. The round window (RW) niche was visible. The OW and RW are labeled to the right above the structures. ... The extreme ossicular abnormalities in this patient with BOR made his maximal conductive hearing loss not amenable to ossiculoplasty. We ultimately failed in our attempt to restore his conductive hearing loss due to agenesis of the oval window and lack of a mobile footplate. The intraoperative endoscopy revelaed the lack of suitable anatomy for an ossicular replacement prosthesis. The findings in our patient highlight the diagnostic findings in BOR on CT scan of the temporal bone and correlate well with his clinical findings. Although BOR patients may not be a homogeneous in terms of their middle ear anatomy, this patient suggests ossiculoplasty may not be a viable option in this population.

Structure and function of the mammalian middle ear. I: Large middle ears in small desert mammals.

Many species of small desert mammals are known to have expanded auditory bullae. The ears of gerbils and heteromyids have been well described, but much less is known about the middle ear anatomy of other desert mammals. In this study, the middle ears of three gerbils (Meriones, Desmodillus and Gerbillurus), two jerboas (Jaculus) and two sengis (elephant-shrews: Macroscelides and Elephantulus) were examined and compared, using micro-computed tomography and light microscopy. Middle ear cavity expansion has occurred in members of all three groups, apparently in association with an essentially 'freely mobile' ossicular morphology and the development of bony tubes for the middle ear arteries. Cavity expansion can occur in different ways, resulting in different subcavity patterns even between different species of gerbils. Having enlarged middle ear cavities aids low-frequency audition, and several adaptive advantages of low-frequency hearing to small desert mammals have been proposed. However, while Macroscelides was found here to have middle ear cavities so large that together they exceed brain volume, the bullae of Elephantulus are considerably smaller. Why middle ear cavities are enlarged in some desert species but not others remains unclear, but it may relate to microhabitat.

Structure and function of the mammalian middle ear. II: Inferring function from structure.

Anatomists and zoologists who study middle ear morphology are often interested to know what the structure of an ear can reveal about the auditory acuity and hearing range of the animal in question. This paper represents an introduction to middle ear function targetted towards biological scientists with little experience in the field of auditory acoustics. Simple models of impedance matching are first described, based on the familiar concepts of the area and lever ratios of the middle ear. However, using the Mongolian gerbil Meriones unguiculatus as a test case, it is shown that the predictions made by such 'ideal transformer' models are generally not consistent with measurements derived from recent experimental studies. Electrical analogue models represent a better way to understand some of the complex, frequency-dependent responses of the middle ear: these have been used to model the effects of middle ear subcavities, and the possible function of the auditory ossicles as a transmission line. The concepts behind such models are explained here, again aimed at those with little background knowledge. Functional inferences based on middle ear anatomy are more likely to be valid at low frequencies. Acoustic impedance at low frequencies is dominated by compliance; expanded middle ear cavities, found in small desert mammals including gerbils, jerboas and the sengi Macroscelides, are expected to improve low-frequency sound transmission, as long as the ossicular system is not too stiff.

The prominent antihelix and helix--the myth of the 'overcorrected' ear in otoplasty.

Classic teaching of ear anatomy in the context of otoplasty states that if the antihelical fold is more prominent than the helical fold after surgery then the ear is "overcorrected." We set out to explore the role of the antihelix in normal ear anatomy, its relevance to aesthetic perceptions of the ear, and a snapshot of its incidence in nonoperated ears. To readily identify junior staff in our department, their color photographs, names, and contact details are posted on every ward. Using digital methods, we cropped the left ear out of the source images, making them unidentifiable. Clinical and nonclinical staff in our unit were asked to choose their favorite and their least favorite ears based on their aesthetic appeal. Responses were tabulated and the 2 most popular ears were compared. The preferred ear did not conform to the traditional dogma because it had a prominent antihelix and was statistically significant when compared to other choices. We also noted that a prominent antihelix is common among the general population and among colleagues within the department, and hence "normal." Also interesting was that the helix of the ear chosen as the most aesthetic was also the ear where the helix was almost touching the side of the head. We found that when judging the aesthetic nature of the "virgin" ear, antihelical fold prominence did not appear to be a negative attribute. Indeed, we noted that a prominent antihelix was a common attribute, and we conclude that this was a normal variant without undue negative aesthetic stigma. A surgically corrected ear should not necessarily be regarded as a poor outcome simply on the basis of antihelical prominence. Furthermore, we postulate that patients who have a prominent antihelix might be part of a spectrum of individuals who might have had the subtype of prominent ears featuring a deep conchal bowl. Finally, although not tested directly, it appears that we do not have an idea of our own ear shape, as none of the participants was able to recognize their own ear from the photographs.

Macroscopic description of the external and middle ear of paca (Cuniculus paca Linnaeus, 1766)

Abstract: Paca (Cuniculus paca), one of the largest rodents of the Brazilian fauna, has inherent characteristics of its species which can conribute as a new option for animal experimantation. As there is a growing demand for suitable experimental models in audiologic and otologic surgical research, the gross anatomy and ultrastructural ear of this rodent have been analyzed and described in detail. Fifteen adult pacas from the Wild Animals Sector herd of Faculdade de Ciências Agrárias e Veterinárias, Unesp-Jaboticabal, were used in this study. After anesthesia and euthanasia, we evaluated the entire composition of the external ear, registering and ddescribing the details; the temporal region was often dissected for a better view and detailing of the tympanic bulla which was removed and opened to expose the ear structures analyzed mascroscopically and ultrastructurally. The ear pinna has a triangular and concave shape with irregular ridges and sharp apex. The external auditory canal is winding in its path to the tympanic mebrane. The tympanic bulla is is on the back-bottom of the skull. The middle ear is formed by a cavity region filled with bone and membranous structures bounded by the tympanic membrane and the oval and round windows. The tympanic membrane is flat and seals the ear canal. The anatomy of the paca ear is similar to the guinea pig and from the viewpoint of experimental model has major advantages compared with the mouse ear.

An Innovative 3-dimensional Model of the Epitympanum for Teaching of Middle Ear Anatomy.

To facilitate teaching of the anatomy of the epitympanum, we developed and evaluated the effectiveness of an interactive 3-dimensional (3D) computer model that can be viewed from all angles. Questionnaire-based prospective randomized controlled trial. Undergraduate medical education program. The model was created using Google Sketchup, a 3D modeling software. We recruited 72 graduating medical students and randomized them into 2 groups. One group was given the 3D model and reading materials on the epitympanic anatomy (3D group), while the other group relied on reading material and pictures (2-dimensional [2D] group). A questionnaire and anatomy quiz assessed the utility of the 3D model in learning the anatomy of the epitympanum. The mean age of the participants was 22 years. There were no statistically significant differences in demographics and previous experience with 3D models. The 3D group was significantly more confident in its ability to identify structures of the epitympanum on pictures and computed tomography scans when compared to the 2D group. Most participants were in favor of the model as a useful learning tool and preferred to use it with an instructor. In the anatomy quiz, the 3D group fared significantly better, achieving a mean score of 65.1% compared to 32.4% in the 2D group (P < .001). The 3D teaching model of the epitympanum is efficacious in short-term recall. By allowing the learner to visualize relations of the epitympanum from all directions, the model aids in appreciation of anatomy and identifications of structures of this region.

Comparing human middle-ear motion and pressure gain across idealized and progressively more realistic three-dimensional finite-element models

The mammalian tympanic membrane (TM) is linked to the cochlea via a flexible and circuitous three-bone ossicular chain for which much of the mass is concentrated away from the entry axis to the cochlea. As the TM area (ATM) is much larger than that of the stapes footplate (AFP) and the length of the malleus (LM) is somewhat longer than the incus (LI), the middle ear is considered to function as a pressure transformer to optimize the flow of vibrations from low-density air to high-density cochlear fluid, with an ideal pressure gain defined as (ATM/AFP)*(LM/LI). Even so, the reasons for this complex ossicular arrangement, as opposed to the more straightforward case of a columella directly connecting the TM to the cochlea, are not entirely clear. We explore the effects of middle-ear anatomy and material properties on ossicular motion and pressure gain by comparing the behavior of a series of 3D finite-element models ranging from idealized simple axisymmetric cases of a flat-circular or conic TM connected to a columella, all the way to an anatomically accurate three-ossicle human middle-ear model based on a micro-CT scan of a temporal bone. In doing this, we will test whether the complex 3D anatomy of the human middle ear can be shown to offer any concrete advantages in terms of pressure gain over a simpler columella design, or whether other possible reasons for this complex design are more likely. [Work supported by R01 DC05960 from the NIDCD of the NIH.]