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In single-reed instruments, the mouthpiece and reed have an essential effect on instrument playability, since they largely determine the range of lip force and blowing pressure required to produce notes. This paper quantitatively examines the effect of three different mouthpiece designs (Selmer S80, Concept, and Spirit) on the range of lip force and blowing pressure combinations in which tone can be produced on the alto saxophone for notes ranging from D3 to D5. Average lip force, blowing pressure, loudness, and tuning are investigated as functions of notes and for three different reed strengths. Characteristics such as lip-force/blowing-pressure playability area (total playability area, TPA) and correctly tuned playability area (CTPA) are determined for different reed strengths and note values, and change of tuning as a function of notes is investigated. Apparent differences were observed between mouthpieces of different designs and even between mouthpieces with extremely similar tip openings. The Spirit mouthpiece is louder but requires higher lip force and more adaptation of lip force and of blowing pressure over note ranges. The Concept, with a remarkably similar tip opening and facing length as the S80, allows for a smoother transition between the low and high registers of the instrument and has better tuning stability. The new parameters < TPA > and < CTPA > are introduced as summarizing indicators of mouthpiece characteristics, averaged over note range and reed strength range. Such parameters can be used to define mouthpiece playability objectively and can form important input for parameter-based design improvement or customization.

Knowing the precise tympanic membrane (TM) thickness variation is crucial in understanding the functional properties of the TM and has a significant effect on the accuracy of computational models. Using optical coherence tomography, we imaged five left and five right TMs of domestic New Zealand rabbits. From these data, ten thickness distribution maps were computed. Although inter-specimen variability is present, similar features could be observed in all samples: The rabbit TM is thickest around the umbo, with values of 150 32 µm. From the umbo towards the TM annulus, the thickness gradually decreases down to 38 7 µm around the midway location, but increases up to 54 19 µm at the TM annulus. The thickness values at the umbo are comparable to literature data for humans, but the rabbit TM is thinner at the TM annulus and in-between the umbo and annulus. Moreover, the rabbit TM thickness distribution is highly symmetrical, which is not the case for the human TM. The results improve our general understanding of TM structure in rabbits and may improve numerical models of TM dynamical behavior.

Recently, synchrotron radiation computed microtomography (SRµCT) has emerged as a promising tool for non-destructive, in situ visualization of cochlear implant electrode arrays inserted into a human cochlea. Histological techniques have been the `gold standard' technique for accurate localization of cochlear implant electrodes but are suboptimal for precise three-dimensional measurements. Here, an SRµCT experimental setup is proposed that offers the benefit of a high spatial and contrast resolution (isotropic voxel size = 4.95 µm and propagation-based phase-contrast imaging), while visualizing the soft-tissue structures and electrode array of the cochlear implant simultaneously. In this work, perimodiolar electrode arrays have been tested, which incorporate thick and closely spaced platinum–iridium contacts and wiring. These data can assist cochlear implant and hearing research, can be used to verify electrode segmentation techniques for clinical computed tomography or could be utilized to evaluate cochlear implant electrode array designs.

Experiments have shown that prestrain exists in the rabbit tympanic membrane (TM), also in the absence of external loads. To date, it is unclear how prestrain influences the vibration response of the middle ear (ME). In this study, a detailed 3D finite-element model of the rabbit ME was constructed based on experimentally validated material properties. The model incorporates different degrees of prestrain in the TM and simulates the ME vibration response to sound as a linear harmonic perturbation around the prestressed reference state. To account for finite deformations associated with large prestrains, a framework was developed that iteratively updates the initial unstrained geometry until the prestrained geometry is in agreement with the given reference geometry. After validating the model using quasi-static and acoustic measurement data, it was shown that small levels of prestrain already have a substantial impact on the normal umbo and footplate response due to a phenomenon known as prestress stiffening. Although the approach is not preferable, it was possible to replicate the effect of prestrain in the normal ME by appropriately scaling the elastic moduli and damping factors in the base model. To evaluate the effect of possible changes in TM prestrain when the normal state of the ear is altered due to pathological modifications in the ME structure, we created a model with a perforation in the TM. It was shown that the change in vibration response after perforation is affected at low frequencies by a release of TM prestrain. In future studies, it may be necessary to incorporate prestrain in ME models to better understand the function of the diseased or reconstructed ME, which may be relevant for the development of reconstructive tissue grafts in the middle ear.

In single reed musical instruments, vibrations of the reed, in conjunction with the geometry of the mouthpiece and the acoustic feedback of the instrument, play an essential role in sound generation. Up until now, three-dimensional (3D) reed vibration patterns have only been studied under external acoustic stimulation, or at a single note and lip force. This paper investigates vibration patterns of saxophone reeds under imitated realistic playing conditions. On different notes displacement measurements on the entire optically accessible part of the reed are performed using stroboscopic digital image correlation. These vibration data are decomposed onto the harmonic frequencies of the generated note pitch and into the operational modes. Motion data as a function of time are shown on single points. All points on the reed predominantly move in phase, corresponding to the first flexural mode of the reed. At higher note harmonics very low amplitude higher vibration modes are superimposed on the fundamental mode. Mouthpiece characteristics and lip force influence the vibration patterns. Vibration patterns differ strongly from earlier measurements on free vibrating reeds. Results show that single-point measurements on the tip of the reed can give a good indication of the 3D vibration amplitude, also at higher note pitches.

Although full-field measurement techniques have been well established, material characterization from these data remains challenging. Often, no closedform solution exists between measured quantities and sought material parameters. In this paper, a novel approach to determine the stiffness of thin curved membranes is proposed, based on the virtual fields method (VFM). Utilizing Kirchhoff-Love shell theory, we show that the displacements can be decomposed into an in-plane displacement and a rotation of the mid-surface of the shell. Consequently, the strain tensor at the outer surface of the shell can then be decomposed into a membrane and a bending part. This allows for the VFM to be applied based only on data of the outer surface and on surfaces of arbitrary curvature. The method is first applied to simulated data. It is shown that the elastic modulus can be identified with less than 5% error if the thickness and Poisson ratio are known accurately. A 5% uncertainty in either the Poisson ratio or the thickness changes the identified value by 5%. Then, the method is applied on experimental data acquired on rubber samples having a dome-like shape. Tensile tests are performed on the same samples, which permits to assess the linearized Young's modulus of this material for moderate strains (0–2.1%). Using regression analysis, a Young's modulus of 1.21 ± 0.08 MPa is found. Next, we performed pressurization tests on eight dome-like shapes with pressures up to 4 kPa. The average Young's modulus obtained with the novel virtual fields method is 1.20 ± 0.13 MPa. The results are in good agreement with the ones from the tensile test. Future applications could benefit from this method to analyse more complex shapes, for example those found in biological structures like arteries or eardrums.

Reed woodwind instruments pose great challenges in modeling because their functioning is based on a combination of hydrodynamics, acoustics, and mechanics. Reproducible measurements therefore remain crucial for further development of reeds and instrument mouthpieces. We present a method to measure reed behavior and acoustic response under realistic, well-defined playing conditions. A measurement setup based on constant phase stroboscopic digital imaging correlation (DIC) is proposed. A computer-controlled timer delay triggering system combined with high-power LEDs allows one to obtain clear images at different phases of the vibrational period. From these high-quality images, digital image correlation DIC allows one to analyze both displacement and strain over the full visible surface of the reed. The presented technique can also be applied to other nonfrequency-imposed vibrating structures. The method is demonstrated on a saxophone reed, and we show how it can be used to determine playability range of a mouthpiece and vibrational behavior of the reed.

Compared to single source systems, stereo X-ray CT systems allow acquiring projection data within a reduced amount of time, for an extended field-of-view, or for dual X-ray energies. To exploit the benefit of a dual X-ray system, its acquisition geometry needs to be calibrated. Unfortunately, in modular stereo X-ray CT setups, geometry misalignment occurs each time the setup is changed, which calls for an efficient calibration procedure. Although many studies have been dealing with geometry calibration of an X-ray CT system, little research targets the calibration of a dual cone-beam X-ray CT system. In this work, we present a phantom-based calibration procedure to accurately estimate the geometry of a stereo cone-beam X-ray CT system. With simulated as well as real experiments, it is shown that the calibration procedure can be used to accurately estimate the geometry of a modular stereo X-ray CT system thereby reducing the misalignment artifacts in the reconstruction volumes.

Characterization of material parameters from experimental data remains challenging, especially on biological structures. One of such techniques allowing for the inverse determination of material parameters from measurement data is the virtual fields method (VFM). However, application of the VFM on general structures of complicated shape has not yet been extensively investigated. In this paper, we extend the framework of the VFM method to thin curved solids in three-dimensional, commonly denoted shells. Our method is then used to estimate the Young's modulus and hysteretic damping of the human eardrum. By utilizing Kirchhoff plate theory, we assume that the behavior of the shell varies linearly through the thickness. The total strain of the shell can then be separated in a bending and membrane strain. This in turn allowed for an application of the VFM based only on data of the outer surface of the shell. We validated our method on simulated and experimental data of a human eardrum made to vibrate at certain frequencies. It was shown that the identified material properties were accurately determined based only on data from the outer surface and are in agreement with literature. Additionally, we observed that neither the bending nor the membrane strain in an human eardrum can be neglected and both contribute significantly to the total strain found experimentally.

An issue in computerized x-ray tomography is the limited size of available detectors relative to objects of interest. A solution was provided in the past two decades by positioning the detector in a lateral offset position, increasing the effective field of view (FOV) and thus the diameter of the reconstructed volume. However, this introduced artifacts in the obtained reconstructions, caused by projection truncation and data redundancy. These issues can be addressed by incorporating an additional data weighting step in the reconstruction algorithms, known as redundancy weighting. In this work, we present an implementation of redundancy weighting in the widely-used simultaneous iterative reconstruction technique (SIRT), yielding the weighted SIRT (W-SIRT) method. The new technique is validated using geometric phantoms and a rabbit specimen, by performing both simulation studies as well as physical experiments. The experiments are carried out in a highly flexible stereoscopic x-ray system equipped with x-ray image intensifiers (XRIIs). The simulations showed that higher values of contrast-to-noise ratio could be obtained using the W-SIRT approach as compared to a weighted implementation of the simultaneous algebraic reconstruction technique (SART). The convergence rate of the W-SIRT was accelerated by including a relaxation parameter in the W-SIRT algorithm, creating the aW-SIRT algorithm. This allowed to obtain the same results as the W-SIRT algorithm, but at half the number of iterations, yielding a much shorter computation time. The aW-SIRT algorithm has proven to perform well for both large as well as small regions of overlap, outperforming the pre-convolutional Feldkamp-David-Kress algorithm for small overlap regions (or large detector offsets). The experiments confirmed the results of the simulations. Using the aW-SIRT algorithm, the effective FOV was increased by >75%, only limited by experimental constraints. Although an XRII is used in this work, the method readily applies to flat-panel detectors as well.

Prestrain in the absence of external loads can have an important effect on the vibrational behavior of mechanical systems such as the middle ear. Studies that measure tympanic membrane (TM) prestrain are scarce, however, and provide no conclusive answer on the existence and nature of the prestrain. In this study, prestrain is measured in the TM of cadaveric rabbit ears by stereo digital image correlation. To release the prestrain, straight incisions of 0.33 mm are made on different locations in the TM with a direction parallel to either the radial or circular fibers in the membrane. The effect of sample dehydration during different stages in the experimental procedure is assessed and eliminated by rehydrating the samples directly before each measurement. The measurements demonstrate average prestrain values around the incisions between 3.52 +/- 2.34% and 13.62 +/- 7.92% for the different locations, with a noise floor of 0.07%. No clear differences were found between the prestrain values obtained for radial and circular incisions. Observed local variations in TM prestrain could not be clearly related to specific locations on the TM. The results suggest that TM prestrain may need to be considered in future studies of middle-ear function if the findings can be confirmed in human ears. (C) 2021 Elsevier B.V. All rights reserved.

Geometric distortion is inevitable in facilities using x-ray image intensifiers. When the induced distortion pattern varies over time, each recorded frame should be corrected accordingly, which is the case in conventional C-arm imaging, for example. This demonstrates the need for reliable and easy-to-use, projection-angle-dependent correction methods. In the present work, we demonstrate such a dynamic approach, based on digital image correlation (DIC). We validate the method in a set-up for high-speed x-ray tomography, where the variable distortion is induced by an inhomogeneous distribution of ferromagnetic components in the sample rotation stage. By comparing the ideal positions of metal beads in a rectilinear pattern and their positions in the corrected radiographs of that pattern, we deduced the minimum number of frames required to estimate the varying distortion behavior during a full revolution of the stage. Next, this method was validated in a geometry calibration algorithm for a tomographic set-up, as well as in a tomographic reconstruction. Before the application of any distortion correction, the recorded images suffer from, on average, a mean and maximum distortion of 11.12 pixels (1.56 mm) and 42.79 pixels (6.10 mm), respectively. From our experiments, we conclude that three projections, sampled with a 120° interval, are sufficient to correct any frame recorded under an intermediate angle, with mean and maximum residual errors respectively below 0.48 pixels (0.068 mm) and 1.68 pixels (0.240 mm) while using a 14” image intensifier covering a 292 mm × 292 mm field of view. These results imply a decrease of the mean and maximum distortion errors of at least 96%, regardless of the projection angle. Next, the results showed improved accuracy in the system’s geometry calibration, which resulted in a reduced blurring of edges and better contrast, as well as shape preservation in the tomographic reconstruction. This demonstrates that the new method is accurate and reliable and, due to the common availability of DIC software, it is very accessible and easy to use.

The vibration response of the middle ear (ME) to sound changes when static pressure gradients are applied across the tympanic membrane (TM). To date, it has not been well understood which mechanisms lead to these changes in ME vibration response. In this study, a 3D finite-element model of the human ME was developed that simulates the sound-induced ME vibration response when positive and negative static pressures of up to 4 kPa are applied to the TM. Hyperelasticity of the soft-tissue components was considered to simulate large deformations under static pressure. Some ME components were treated as viscoelastic materials to capture the difference between their static and dynamic stiffness, which was needed to replicate both static and dynamic ME behavior. The change in dynamic stiffness with static preload was simulated by linearization of the hyperelastic constitutive model around the predeformed state. For the preloaded harmonic response, we found that the statically deformed ME geometry introduced asymmetry in the vibration loss between positive and negative pressure, which was due to the TM cone shape. As opposed to previous assumptions, the prestress in the ME due to static pressure had a substantial impact on the vibration response. We also found that material nonlinearity led to a higher stiffening at the umbo but a less pronounced stiffening at the footplate compared to the linear elastic condition. The results suggest that flexibility of the incudomalleolar joint (IMJ) enhances the decoupling of static umbo and footplate displacements, and that viscosity and viscoelasticity of the IMJ could play a role in the transfer of sound-induced vibrations from the umbo to the footplate. The components of the incudostapedial joint had minimal effect on ME mechanical behavior.

An otoendoscopic structured-light system based on fringe-projection profilometry is presented. Two standard rigid otoendoscopes are mounted onto each other and combined with a digital light projector and high-speed camera with respective frame rates of 120 and 210 Hz. Four phase-shifted sinusoidal fringe patterns are projected onto the object’s surface through the imaging channel of one endoscope with a 0° viewing angle, and the fringe patterns reflected by the object are recorded by the camera via the imaging channel of the other endoscope with a 30° viewing angle, resulting in a 3D shape measurement speed of 30 Hz in the current setup. Due to the angle between the projection and imaging axis, the projected patterns appear deformed by the object’s shape to the camera, enabling the reconstruction of its full-field surface height map. Geometric lens distortions in the optics of the projection and imaging channels were calibrated, resulting in a depth measurement precision between 10 and 30 µm and a lateral resolution of 10 to 25 µm. Otoendoscopic profilometry adds an extra dimension of depth to the standard 2D otoendoscopic image and can be used as a noninvasive technique to expand the qualitative depth perception of the physician with quantitative 3D data of the tympanic-membrane surface. Hence, the system holds the potential to provide objective diagnosis of tympanic-membrane and middle-ear disease. In future, the system will be optimized to allow real-time surface-shape visualization and handheld operation for use in a clinical setting.

The nature of the movement of the columellar footplate (CFP) in birds is still a matter of ongoing debate. Some sources claim that rocking motion is dominant, while others propose a largely piston-like motion. In this study, motions of the CFP are experimentally investigated in the ostrich using a post-mortem approach. For quasi-static loads, micro-CT scans of ostrich heads were made under positive and negative middle-ear pressures of 1 kPa. For dynamic loads, laser Doppler vibrometry was used to measure the velocity on multiple locations of the CFP as a function of excitation frequency from 0.125 to 4 kHz, and digital stroboscopic holography was used to assess the 1D full-field out-of-plane displacement of the CFP at different excitation frequencies. To expose the CFP in the experiments, measurements were made from the medial side of the CFP after opening and draining the inner ear. To determine the influence of the inner-ear load on CFP motions, a finite element model was created of the intact ostrich middle ear with inner-ear load included. For quasi-static loads, the CFP performed largely piston-like motions under positive ME pressure, while under negative ME pressure the difference between piston and rocking motion was smaller. For dynamic loads, the CFP motion was almost completely piston-like for frequencies below 1 kHz. For higher frequencies, the motions became more complicated with an increase of the rocking components, although they never exceeded the piston component. When including the inner-ear load to the model, the rocking components started to increase relative to the piston component when compared to the result of the model with unloaded CFP, but only at high frequencies above 1 kHz. In this frequency range, the motion could no longer be identified as purely piston-like or rocking. As a conclusion, the current results suggest that CFP motion is predominantly piston-like below 1 kHz, while at higher frequencies the motion becomes too complicated to be described as purely piston-like or rocking.

The detection of delaminations in composite laminates using automated thermographic scanning is a quite challenging task. The set-up parameters are not only dependent on the equipment, but on the inspected component as well. In this work, a methodology is discussed to use Finite Element (FE) model updating to automatically establish the most suitable inspection parameters for a given combination of the structure and the investigated delamination depths. The optimised results are compared using binary Probability of Detection analysis and are benchmarked with parameter sets retrieved by an expert using the regular trial & error approach. The results show an improvement of the accuracy and scanning speed which significantly increases as the POD decreases and the complexity of the samples increases.

It has long been supposed that the middle-ear has near to perfect linear characteristics, and several attempts have been made to investigate this hypothesis. In conclusion, the middle-ear was regarded as a linear system at least up till sound pressure levels of 120 dB. Because of the linear relationship between Doppler shift of light and the vibration velocity of the object on which the light is reflected, laser Doppler vibrometry (LDV) is an intrinsically highly linear measurement technique. Therefore it allows straightforward detection of very small nonlinearities in a vibration response. In this paper, laser Doppler vibrometry and multisine stimulation are used to detect nonlinear distortions in the vibration response at the umbo of the tympanic membrane of seven human cadaver temporal bones. Nonlinear distortions were detected starting from sound pressure levels of 99 dB and measurements were performed up to 120 dB. These distortions can be subdivided into even degree (e.g. quadratic distortion tones) and odd degree nonlinear distortions (e.g. cubic distortion tones). We illustrate that with odd multisine stimulation the level of even and odd degree nonlinear distortions can be investigated separately. In conclusion, laser Doppler vibrometry is an adequate tool to detect nonlinear distortions in the middle-ear system and to quantify the level of such distortions even at 57 dB below the vibration response. The possibility to analyze even degree and odd degree nonlinear distortion levels separately can help in future work to pinpoint the source of the nonlinearity.

The aim of this work, was to compare pulse wave velocity (PWV) measurements using Laser Doppler vibrometry (LDV) and the more established ultrasound-based pulse wave imaging (PWI) in smooth vessels. Additionally, it was tested whether changes in phantom structure can be detected using LDV in vessels containing a local hardening of the vessel wall. Results from both methods showed good agreement illustrated by the non-parametric Spearman correlation analysis (Spearman-ρ = 1 and p

In this paper, we investigate the heating function of the nasal cavity qualitatively, using a high-quality, large-scale statistical shape model. This model consists of a symmetrical and an asymmetrical part and provides a new and unique way of examining changes in nasal heating function resulting from natural variations in nasal shape (as obtained from 100 clinical CT scans). Data collected from patients suffering from different nasal or sinus-related complaints are included. Parameterized models allow us to investigate the effect of continuous deviations in shape from the mean nasal cavity. This approach also enables us to avoid many of the compounded effects on flow and heat exchange, which one would encounter when comparing different patient-specific models. The effects of global size, size-related features, and turbinate size are investigated using the symmetrical shape model. The asymmetrical model is used to investigate different types of septal deviation using Mladina's classification. The qualitative results are discussed and compared with findings from the existing literature.

This work proposes a method from which a heterogeneous and isotropic stiffness can be estimated from human eardrums. Under normal hearing conditions, neither the bending nor the membrane strains can be neglected on such a sample. Due to this, the Virtual Fields Method was adapted by invoking specific assumptions related to the Kirchhoff Love plate model, so both strain types could be taken into account during the inverse method. Apart from this contribution, specific virtual fields were designed, so the virtual work could be computed on enclosed domains. By neglecting spatial stiffness variations within the prescribed regions, such an estimation could be performed locally. Those attempts were validated on the basis of a Finite-element model and the identified stiffness distribution was in agreement with the reference one. Due to the quality of the preliminary results, the proposed method has shown itself to be a reliable tool to identify heterogeneous material properties on shell-like structures.

Conductive hearing loss, due to middle ear pathologies or traumas, affects more than 5% of the population worldwide. Passive prostheses to replace the ossicular chain mainly rely on piston-like titanium and/or hydroxyapatite devices, which in the long term suffer from extrusion. Although the basic shape of such devices always consists of a base for contact with the eardrum and a stem to have mechanical connection with the residual bony structures, a plethora of topologies have been proposed, mainly to help surgical positioning. In this work, we optimize the topology of a total ossicular replacement prosthesis, by maximizing the global stiffness and under the smallest possible volume constraint that ensures material continuity. This investigation optimizes the prosthesis topology in response to static displacement loads with amplitudes that normally occur during sound stimulation in a frequency range between 100 Hz and 10 kHz. Following earlier studies, we discuss how the presence and arrangement of holes on the surface of the prosthesis plate in contact with the umbo affect the overall geometry. Finally, we validate the designs through a finite-element model, in which we assess the prosthesis performance upon dynamic sound pressure loads by considering four different constitutive materials: titanium, cortical bone, silk, and collagen/hydroxyapatite. The results show that the selected prostheses present, almost independently of their constitutive material, a vibroacustic behavior close to that of the native ossicular chain, with a slight almost constant positive shift that reaches a maximum of approximate to 5 dB close to 1 kHz. This work represents a reference for the development of a new generation of middle ear prostheses with non-conventional topologies for fabrication via additive manufacturing technologies or ultraprecision machining in order to create patient-specific devices to recover from conductive hearing loss.

Objective: We compared the sound transmission using different types of total ossicular replacement prostheses (TORP); we then studied the performance of a new TORP that we designed inspired by the columella, the single ossicle found in birds. Methods: Stapedial vibrations were measured on nine freshly frozen human temporal bones with laser Doppler vibrometry. We then compared the performances of eight common TORP positions or designs as well as the new silver prototype of bird-type prosthesis, designed also according to our digital holography patterns of the human tympanic membrane (TM). Results: The TORPs placed in lateral contact with both the TM and the malleus handle outperformed, at most frequencies, those placed only in contact with the TM. The new bird-type prosthesis performed equally well or better than all other prostheses. Conclusion: If the malleus handle can be retained when placing a TORP, the best sound transmission can be achieved by placing the TORP in contact with both the distal part of the malleus handle and the TM. The good performance of our bird-type prosthesis suggests that there is still room for future improvement of prosthesis design to further optimize hearing outcomes after surgery.

The reed is the primary component in single-reed woodwind instruments to generate the sound. The airflow of the player&rsquo, s mouth is the energy source and the airflow is modulated by the reed. The oscillations of the reed control the airflow. Traditionally, instrument reeds are made out of natural cane (Arundo Donax), but in efforts to overcome variability problems, synthetic reeds have been introduced. Previous investigations mainly focused on natural cane reeds and direct elasticity measurements did not discriminate between elasticity moduli along different directions. In order to obtain the mechanical properties along the direction of the reed fibres and in the orthogonal direction separately, a three-point bending testing setup was developed, which accommodates the small samples that can be cut from an instrument reed. Static moduli of elasticity were acquired in both directions. Much higher ratios between longitudinal and transversal moduli were seen in the natural cane reed as compared to the artificial reeds. Wet natural reeds showed a strong decrease in moduli of elasticity as compared to dry reeds. Elasticity was significantly higher in artificial reeds. The force&ndash, displacement curves of the wet natural reed show hysteresis, whereas the artificial materials did not. In the cane reed, higher energy losses were found in the transversal direction compared to the longitudinal direction

It is believed that non-mammals have poor hearing at high frequencies because the sound-conduction performance of their single-ossicle middle ears declines above a certain frequency. To better understand this behavior, a dynamic three-dimensional finite-element model of the chicken middle ear was constructed. The effect of changing the flexibility of the cartilaginous extracolumella on middle-ear sound conduction was simulated from 0.125 to 8 kHz, and the influence of the outward-bulging cone shape of the eardrum was studied by altering the depth and orientation of the eardrum cone in the model. It was found that extracolumella flexibility increases the middle-ear pressure gain at low frequencies due to an enhancement of eardrum motion, but it decreases the pressure gain at high frequencies as the bony columella becomes more resistant to extracolumella movement. Similar to the inward-pointing cone shape of the mammalian eardrum, it was shown that the outward-pointing cone shape of the chicken eardrum enhances the middle-ear pressure gain compared to a flat eardrum shape. When the outward-pointing eardrum was replaced by an inward-pointing eardrum, the pressure gain decreased slightly over the entire frequency range. This decrease was assigned to an increase in bending behavior of the extracolumella and a reduction in piston-like columella motion in the model with an inward-pointing eardrum. Possibly, the single-ossicle middle ear of birds favors an outward-pointing eardrum over an inward-pointing one as it preserves a straight angle between the columella and extrastapedius and a right angle between the columella and suprastapedius, which provides the optimal transmission.

Purpose X-ray image intensifiers (XRIIs) inevitably produce images suffering from geometric distortion. Presently, various local and global methods exist to correct for these distortions. However, the performance of global methods is limited for dominant local distortions, and local methods tend to suffer from patch discontinuity and are generally sensitive to noise. In this paper, a novel local method is presented based on digital image correlation (DIC), which does not suffer from patch discontinuity and noise. Methods As DIC is a very accurate and robust technique to analyze deformations, it is our candidate of choice to outperform the existing correction methods. The performance of our technique was first validated through distortion simulations. Next, it was validated experimentally for four different orientations of the XRII. Results A theoretical study on images suffering from a simulated distortion (including noise and blurring) yielded corrections with an average accuracy of (0.20 +/- 0.04) pixels. We obtained experimental data with our 14" XRII (292 mm field of view), suffering from a maximum distortion between 9.6 and 12.9 mm, and an average distortion between (4.4 +/- 1.3) mm and (6.1 +/- 2.5) mm over the image field for the different orientations. For an adequate choice of the facet size in the DIC analysis (greater than 40 pixels), the weighted mean residual error of our method varied between (0.037 +/- 0.003) mm and (0.054 +/- 0.003) mm, regardless of the XRII orientation. The maximum residual error varied between 0.081 and 0.185 mm. Conclusions From the simulations, we concluded that the proposed technique is affected by neither Gaussian noise nor blurring. Furthermore, it is shown that our method can reach an accuracy that is on par with or better than the current standard tools. The novel method is fast, requires minimal operator intervention and can be fully automated.

The computation of the structural intensity on the basis of measured displacement fields is an approach that permits the visualization of energy paths taking place on thin structures. The development of such an analysis is made feasible when the sample is assumed to behave in accordance with the Kirchhoff-Love postulates. This permits the generalized forces within the structure to be estimated through the differentiation of displacement data, which in turn are the inputs to assess the vibrational energy flow. Such an analysis is widely documented in cases, which the sample is either a plate or a shell-like structure with simple geometrical configurations. However, it is from the author’s knowledge that such an analysis has not yet been performed on arbitrary geometries, such as doubly curved shells. This work proposes a method that allows the structural intensity of an arbitrary geometry to be computed on the basis of measured displacement fields and spatial coordinates from a sample’s outer-surface. After measuring these fields via a Digital Image Correlation set-up, it is assumed that the geometrical data can be represented as an assembly of flat plates. The elements of this assembly overlap with the sample’s spatial coordinates and are treated as the constituents of a finite element mesh. Afterwards, the experimental displacement fields are projected on the nodes of that mesh via a global least-squares minimization approach, which in turn enables the nodal deformations to be differentiated with proper finite element shape functions. By assuming that the elements of the mesh behave in accordance with the Kirchhoff-plate theory, it is feasible to estimate the generalized forces on the sample’s mid-surface and to assess the structural intensity vector field. By treating the geometrical spatial coordinates as a finite element mesh and the displacement data as projected degrees of freedom, the presented method has shown itself to be a reliable tool to extract the vibrational energy taking place on arbitrary shells.

Asphalt mixtures are the most common types of pavement material used in the world. Characterizing the mechanical behavior of these complex materials is essential in durable, cost-effective, and sustainable pavement design. One of the important properties of asphalt mixtures is the complex modulus of elasticity. This parameter can be determined using different standardized methods, which are often expensive, complex to perform, and sensitive to the experimental setup. Therefore, recently, there has been considerable interest in developing new, easier, and more comprehensive techniques to investigate the mechanical properties of asphalt. The main objective of this research is to develop an alternative method based on an optical measurement technique (laser Doppler vibrometry). To do this, a frequency domain system identification technique based on analytical formulas (Timoshenko’s beam theory) is used to determine the complex modulus of asphalt concrete at its natural frequencies and to form their master curve. The master curve plotted by this method is compared with the master curve obtained from the standard four-point bending test, and it is concluded that the proposed method is able to produce a master curve similar to the master curve of the standard method. Therefore, the proposed method has the potential to replace the standard stiffness tests. Furthermore, the standard stiffness methods usually conduct experiments up to the maximum frequency of 30 Hz. However, the proposed method can provide accurate complex modulus at high frequencies. This makes an accurate comparison between the properties of the asphalt mixtures in high frequencies and the development of more accurate theoretical models for simulation of specimens possible.

The eardrum is the primary component of the middle ear and has been extensively investigated in humans. Measuring the displacement and deformation of the eardrum under different quasi-static loading conditions gives insight in its mechanical behavior and is fundamental in determining the material properties of the eardrum. Currently, little is known about the behavior and material properties of eardrums in non-mammals. To explore the mechanical properties of the eardrum in non-mammalian ears, we investigated the quasi-static response of the eardrum of a common lizard: the Tokay gecko (Gekko gecko). The middle ear cavity was pressurized using repetitive linear pressure cycles ranging from −1.5 to 1.5 kPa with pressure change rates of 0.05, 0.1 and 0.2 kPa/s. The resulting shape, displacement and in-plane strain of the eardrum surface were measured using 3D digital image correlation. When middle-ear pressure is negative, the medial displacement of the eardrum is much larger than the displacement observed in mammals; when middle-ear pressure is positive, the lateral displacement is much larger than in mammals, which is not observed in bird single-ossicle ears. Peak-to-peak displacements are about 2.8 mm, which is larger than in any other species measured up to date. The peak-to-peak displacements are at least five times larger than observed in mammals. The pressure-displacement curves show hysteresis, and the energy loss within one pressure cycle increases with increasing pressure rate, contrary to what is observed in rabbit eardrums. The energy lost during a pressure cycle is not constant over the eardrum. Most energy is lost at the region where the eardrum connects to the hearing ossicle. Around this eardrum-ossicle region, a 5% increase in energy loss was observed when pressure change rate was increased from 0.05 kPa/s to 0.2 kPa/s. Other parts of the eardrum showed little increase in the energy loss. The orientation of the in-plane strain on the eardrum was mainly circumferential with strain amplitudes of about +1.5%. The periphery of the measured eardrum surface showed compression instead of stretching and had a different strain orientation. The TM of Gekko gecko shows the highest displacements of all species measured up till now. Our data show the first shape, displacement and deformation measurements on the surface of the eardrum of the gecko and indicate that there could exist a different hysteresis behavior in different species.

Human middle ears show large morphological variations. This could affect our perception of hearing and explain large variation in experimentally obtained transfer functions. Most morphological studies focus on capturing variation by using landmarks on cadaveric temporal bones. We present statistical shape analysis based on clinical cone beam CT (CBCT) scans of 100 patients. This allowed us to include surface information on the incudomallear (IM) complex (joint, ligaments and tendon not included) of 123 healthy ears with a scanning resolution of 150 μm and without a priori assumptions. Statistical shape modeling yields an average geometry for the IM complex and the variations present in the population with a high precision. Mean values, variation and correlations among anatomical features (length of manubrium, combined length of malleus head and neck, lengths of incus long and short process, enclosing angles, ossicular lever ratio, incudomallear angle, and principal moments of inertia) are reported and compared to results from the literature. Most variation is found in overall size and the angle between incus and malleus. The compact representation provided by statistical shape modeling is demonstrated and its benefits for surface modeling are discussed.

Determining the degree of ossicular fixation is a difficult task, with the final assessment often being made with manual palpation during exploratory tympanotomy. A more objective method to evaluate ossicular fixation would be valuable. In this paper we describe a new method which makes use of a magnet and coil to measure ossicular motion through the ear canal with an elevated tympanic membrane. We report measurements of the vibration response at the umbo, the tip of the incus long process and the lateral posterior crus of the stapes before and after artificially fixing the stapes footplate and anterior mallear ligament with luting cement. Results were obtained on temporal bones, but the practicality of the method allows easy clinical implementation. Velocity ratios between different measurement points along the ossicular chain may provide a quantitative indication of the degree of stapes fixation. Isolated anterior mallear ligament fixation was not distinguishable from the unfixed condition. (C) 2016 Elsevier B.V. All rights reserved.

The fibrocartilaginous eustachian tube is part of a system of contiguous organs including the nose, palate, rhinopharynx, and middle ear cleft. The middle ear cleft consists of the tympanic cavity, which includes the bony eustachian tube (protympanum) and the mastoid gas cells system. The tympanic cavity and mastoid gas cells are interconnected and allow gaseous exchange and pressure regulation. The fibrocartilaginous eustachian tube is a complex organ consisting of a dynamic conduit with its mucosa, cartilage, surrounding soft tissue, peritubal muscles (ie, tensor and levator veli palatine, salpingopharyngeus and tensor tympani), and superior bony support (the sphenoid sulcus).

Background The tympano-mallear connection (TMC) is the soft-tissue connection between the tympanic membrane (TM) and the manubrium of the malleus. Some studies suggest that its mechanical properties may have a substantial influence on the mechanics and transfer function of the middle ear. However, relatively little is known about the dimensions of the TMC and its variability among individuals. Method Thirteen samples were collected from human temporal bones, consisting of only the malleus and the TM. They were imaged using μCT without contrast enhancing agent. From the μCT images, the TMC dimensions were measured in both anterior–posterior direction (TMC width) and medial-lateral direction (TMC thickness). Three selected samples were examined using histological microscopy. Results Both TMC width and thickness featured a large variability among individuals. The minimal TMC width along the manubrium for different individuals covered a range between 83 and 840 μm. The minimal thickness ranged from 48 to 249 μm and the maximal thickness from 236 to 691 μm. Histological sections showed that the TMC consists of a narrow core of dense regular connective tissue, surrounded by loose connective tissue. In some samples, either of these two components was absent in the TMC at some manubrium locations. The configuration of these components varied among the samples as well. Conclusion Our data confirm that a large inter-individual variability exists in the properties of the TM-malleus connection in humans in terms of its dimensions, tissue composition and configuration. Average data and their variability margins will be useful input for testing the importance of the TMC in finite element models.

In both mammals and birds, the mechanical behavior of the middle ear structures is affected by the mechanical impedance of the inner ear. In this study, the aim was to quantify the acoustic impedance of the avian inner ear in the ostrich, which allows us to determine the effect on columellar vibrations and middle ear power flow in future studies. To determine the inner ear impedance, vibrations of the columella were measured for both the quasi-static and acoustic stimulus frequencies. In the frequency range of 0.3–4 kHz, we used electromagnetic stimulation of the ossicle and a laser Doppler vibrometer to measure the vibration response. At low frequencies, harmonic displacements were imposed on the columella using piezo stimulation and the resulting force response was measured with a force sensor. From these measurement data, the acoustic impedance of the inner ear could be determined. A simple RLC model in series of the impedance measurements resulted in a stiffness reactance of KIE = 0.20·1012 Pa/m³, an inertial impedance of MIE = 0.652·106 Pa s2/m³, and a resistance of RIE = 1.57·109 Pa s/m. We found that values of the inner ear impedance in the ostrich are one to two orders in magnitude smaller than what is found in mammal ears.

Hypothesis: In the literature several surgical methods have been reported that aim to improve hearing in patients with isolated malleus fractures; however, it is still not clear which method gives the best results. Background: In this study, laser Doppler vibrometry (LDV) was used to compare the outcome of different surgical methods on malleus fractures in fresh frozen human temporal bones. Methods: Fractured malleus shafts of defrosted human temporal bones were repaired with bone cement, with a malleus prosthesis from cortical bone, or with a partial ossicular replacement prosthesis (PORP) from cortical bone, and LDV measurements were obtained for analysis. Results: The best result was achieved with the bone cement only, applied directly at the site of the fracture. The malleus prosthesis and the PORP gave similar results. Conclusion: All three surgical methods gave good results, but when the distal end of the fractured malleus can be attached close to the proximal end, the technique using only cement tends to be the best option. If the parts are too far apart, a malleus prosthesis or a PORP would be good options.

Cardiovascular diseases (CVD) are the most prevalent cause of death in the Western World, and their prevalence is only expected to rise. Several screening modalities aim at detecting CVD at the early stages. A common target for early screening is common carotid artery (CCA) stiffness, as reflected in the pulse wave velocity (PWV). For assessing the CCA stiffness using ultrasound (US), one-dimensional (1D) measurements along the CCA axis are typically used, ignoring possible boundary conditions of neck anatomy and the US probe itself. In this study, the effect of stresses and deformations induced by the US probe, and the effect of anatomy surrounding CCA on a simulated 1D stiffness measurement (PWVus) is compared with the ground truth stiffness (PWVgt) in 60 finite-element models (FEM) derived from anatomical computed tomography (CT) scans of ten healthy male volunteers. Based on prior knowledge from the literature, and from results in this study, we conclude that it is safe to approximate arterial stiffness using 1D measurements of compliance or pulse wave velocity, regardless of boundary conditions emerging from the anatomy or from the measurement procedure.

Structural intensity on plates or shells can provide insights on how the vibrational energy is transmitted throughout a sample. Its assessment via experimental deflections are widely documented in the case of plates, which just requires the computation of spatial derivatives of out-of-plane displacements or velocities and a knowledge of the sample's material properties. However, if the structural intensity is to be assessed on arbitrary shells, a more elaborate data processing is required. The in-plane displacements become relevant terms and the spatial derivatives along a predefined local coordinate system need to be computed. Here, a method from which experimental data is interpolated on a finite element mesh is proposed. First, the global displacements and shape of a sample's outer-surface are measured. These data are then projected on a quadratic mesh, where the Kirchhoff plate theory is invoked for the individual elements. The data differentiation is computed via quadratic shape functions, from which the strains and structural intensity are estimated. Through the obtained vibrational energy results on the basis of measured displacement and shape data and by validating the method via a numerical simulation, the proposed work has shown to be a reliable tool to assess energy transmission on irregular shells.

A method is presented to assess the transmission path of vibration energy and to localize sources or sinks on shells with arbitrary shape, constant thickness and isotropic material properties. The derived equations of the structural intensity are based on the Kirchhoff-Love postulates and are formulated in terms of displacements, Lamé parameters, principal curvatures, and their partial derivatives with respect to the principal curvilinear coordinates. To test the accuracy of the method, two numerical models of thin shells with non-uniform curvatures were developed. The coordinates, displacements and principal curvature directions at the shell's outer surface were used to estimate the structural intensity vector fields and the energy density at the shell's middle surface. The power estimated from the surface integral of the divergence of the structural intensity over the source was compared to the actual power injected in the shell. The absolute error in both models did not exceed 1%, showing that, in theory, the method is able to handle the high-order spatial derivatives of the displacement and geometry data. The qualitative effect of varying the internal damping in the models on the energy transmission was also investigated.

The fatigue performance and healing ability of asphalt pavements are important for mixture design, rehabilitation, and maintenance of the roads. By analyzing these parameters in an asphalt mixture, it is possible to predict the crack formation and propagation in asphalt pavements and healing of these cracks during the rest periods. The healing effect in asphalt mixtures has been observed and verified by many researchers and different methods exist to evaluate this phenomenon. However, current methods are still inadequate to fully observe and quantify the healing phenomenon in asphalt mixtures. In this study, a digital image correlation (DIC) method is used to calculate the strain map on the surface of cylindrical asphalt specimens during the indirect tensile fatigue test. This strain map is used to detect the location of crack initiations and development of the microcracks during the experiments. Next, the specimens are unloaded and the temperature of the climate chamber is increased to 60 &deg, C for 18 h to investigate the healing phenomenon on the surface of the specimens. It is observed that the strain reduces near the microcrack areas especially at the tip of the microcracks. Furthermore, using DIC it is possible to observe the healing rate and the minimum time required to heal the microcracks on the surface of the specimens.

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 sogrei), using finite-element modeling. Based on high-resolution mu CT 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 inner-ear loading not only influences sound perception but also sound localization in internally connected ears. (C) 2019 Elsevier B.V. All rights reserved.

The nose is a complex and important organ with a multitude of functions. Computational fluid dynamics (CFD) has been shown to be a valuable tool to obtain a better understanding of the functioning of the nose. CFD simulations require a surface geometry, which is constructed from tomographic data. This can be a very time-consuming task when one chooses to exclude the sinuses from the simulation domain, which in general keeps the size of the CFD model more manageable. In this work, an approach for the semi-automatic construction of the human nasal cavity is presented. In the first part, limited manual interaction is needed to create a coarse surface model. In the next part, this result is further refined based on the combination of active shape modeling with elastic surface deformation. The different steps are bundled in a Matlab toolbox with a graphical interface which guides the user. This interface allows easy manipulation of the data during intermediate steps, and also allows manual adjustments of the reconstructed nasal surface at the end. Two results are shown, and the approach and its precision are discussed. These results demonstrated that the followed approach can be used for the semi-automatic segmentation of a human nasal cavity from tomographic data, substantially reducing the amount of operator time.

A laser Doppler vibrometer (LDV) is a noncontact optical measurement device to measure the vibration velocities of particular points on the surface of an object. Even though LDV has become more popular in road engineering in recent years, their signal-to-noise ratio (SNR) is strongly dependent on light scattering properties of the surface which, in some cases, needs to be properly conditioned. SNR is the main limitation in LDV instrumentation when measuring on low diffusive surfaces like pavements, therefore, an investigation on the SNR of different LDV devices on different surface conditions is of great importance. The objective of this research is to investigate the quality of two types of commercially available LDV systems&mdash, helium&ndash, neon (He&ndash, Ne)-based vibrometers and recently developed infrared vibrometers&mdash, on different surface conditions, i.e., retroreflective tape, white tape, black tape, and asphalt concrete. Both noise floor and modal analysis experiments are carried out on these surface conditions. It is shown that the noise floor of the He&ndash, Ne LDV is higher when dealing with a noncooperative dark surface, such as asphalt concrete, and it can be improved by improving the surface quality or by using an infrared LDV, which consequently improves the modal analysis experiments performed on pavement materials.

The human nose is a complex organ that shows large morphological variations and has many important functions. However, the relation between shape and function is not yet fully understood. In this work, we present a high quality statistical shape model of the human nose based on clinical CT data of 46 patients. A technique based on cylindrical parametrization was used to create a correspondence between the nasal shapes of the population. Applying principal component analysis on these corresponded nasal cavities resulted in an average nasal geometry and geometrical variations, known as principal components, present in the population with a high precision. The analysis led to 46 principal components, which account for 95% of the total geometrical variation captured. These variations are first discussed qualitatively, and the effect on the average nasal shape of the first five principal components is visualized. Hereafter, by using this statistical shape model, two application examples that lead to quantitative data are shown: nasal shape in function of age and gender, and a morphometric analysis of different anatomical regions. Shape models, as the one presented here, can help to get a better understanding of nasal shape and variation, and their relationship with demographic data.

© 2018 Elsevier Ltd The analysis of structural intensity vector fields has shown to be a practical approach to characterize the energy flow in plate-like structures and to localize regions of injected or absorbed power. Such an analysis is performed by differentiating measured velocity or displacement fields of a sample. The quality of such a study strongly depends on the spatial resolution of the deformation data and its signal-to-noise ratio. The digital stroboscopic holography concept is presented in this work and used as a tool to record such deformations on a flat plate, which is in direct contact with a shaker and a damper. The current set-up could provide the recording of displacement fields at a high spatial resolution showing little corruption by noise. These conditions permitted the measurement of deformation patterns containing short wavelengths, which were later used as inputs for the structural intensity analysis. By calculating the spatial derivatives of several out-of-plane displacement fields, the energy flowing through the plate was estimated and the position of the external devices (shaker and damper) could be identified by locating regions of the energy dispersion or convergence. The location of these specific regions was made even clearer by calculating the divergence of the energy flow. ispartof: JOURNAL OF SOUND AND VIBRATION vol:428 pages:168-178 status: published

In the single-ossicle ear of chickens, the quasi-static displacement of the umbo shows great asymmetry; umbo displacements are much larger for negative than for positive pressure in the middle ear, which is opposite to the typical asymmetry observed in mammal ears. To better understand this behavior, a finite-element model was created of the static response of the chicken middle ear. The role of flexibility of the extracolumella in the model was investigated, and the potential effect of the outward orientation of the tympanic-membrane cone was studied by building two adapted models with a flat membrane and an inverted conical membrane. It is found that the extracolumella must be made of flexible material to explain the large inward displacements of the umbo, and that displacements of the footplate are much smaller due to bending of the flexible extracolumella. However, increasing extracolumellar stiffness mostly reduces umbo displacement rather than increasing footplate displacement. The results suggest that the inverted orientation of the membrane cone is responsible for the change in asymmetry of the umbo displacement curve. The asymmetry of the footplate displacement curve in the normal model is smaller, but increases towards positive middle-ear pressure in the case of a flat or inverted membrane geometry.

Accurate determination of the mechanical properties of asphalt concrete is very important in Road Engineering. The traditional method to calculate these properties is to run experiments using a hydraulic/pneumatic actuator and strain gauges to apply stress and measure the strain. However, in the last decade optical measurement techniques have become popular for strain calculation on the surface of the specimen and detecting the cracks on the surface. In this study, digital image correlation is used to estimate the strain map on the surface of an asphalt specimen, predict the location of crack initiation, and investigate the healing phenomenon in asphalt concrete.

Using laser vibrometry and a stimulation and signal analysis method based on multisines, we have measured the response and the nonlinearities in the vibration of the rabbit middle ear at the level of the umbo and the stapes. With our method, we were able to detect and quantify nonlinearities starting at sound pressure levels of 93-dB SPL. The current results show that no significant additional nonlinearity is generated as the vibration signal is passed through the middle ear chain. Nonlinearities are most prominent in the lower frequencies (125 Hz to 1 kHz), where their level is about 40 dB below the vibration response. The level of nonlinearities rises with a factor of nearly 2 as a function of sound pressure level, indicating that they may become important at very high sound pressure levels such as those used in high-power hearing aids.

Numerous imaging techniques measure data that are mathematically wrapped to the finite interval [−π, π], corresponding to the principle value domain of the arctangent function. A wide range of reconstruction algorithms has been developed to obtain the true, unwrapped phase by adding an integral multiple of 2π to each point of the wrapped grid. However, the phase unwrapping procedure is hampered by the presence of noise, phase vortices or insufficiently sampled digital data. Unfortunately, reliable phase unwrapping algorithms are generally computationally intensive and their design often requires multiple iterations to reach convergence, leading to high execution times. In this paper, we present a high-speed phase unwrapping algorithm that is robust against noise and phase residues. By executing the parallel implementation of a single-step Fourier-based phase unwrapping algorithm on the graphics processing unit of a standard graphics card, we were able to reduce the total processing time of the phase unwrapping algorithm to &lt, 5 ms when executed on a 640 × 480-pixel input map containing an arbitrarily high density of phase jumps. In addition, we expand upon this technique by inserting the obtained solution as a preconditioner in the conjugate gradient technique. This way, phase maps that contain regions of low-quality or invalid data can be unwrapped iteratively through weighting of local phase quality.

A multitude of morphological aspects of the human middle ear (ME) were studied qualitatively and/or quantitatively through the postprocessing and interpretation of micro-CT (micro X-ray computed tomography) data of six human temporal bones. The samples were scanned after phosphotungstic acid staining to enhance soft-tissue contrast. The influence of this staining on ME ossicle configuration was shown to be insignificant. Through postprocessing, the image data were converted into surface models, after which the approaches diverged depending on the topics of interest. The studied topics were: the ME ligaments; morphometric and mechanical parameters of the ossicles relating to inertia and the ossicular lever arm ratio; the morphology of the distal incus; the contact surface areas of the tympanic membrane (TM) and of the stapes footplate; and the thickness of the TM, round window of the cochlea, ossicle joint spaces, and stapedial annular ligament. Some of the resulting insights are relevant in ongoing discussions concerning ME morphology and mechanical functions, while other results provide quantitative data to add to existing data. All findings are discussed in the light of other published data and many are relevant for the construction of mechanical finite element simulations of the ME. J. Morphol. 276:1025–1046, 2015. © 2015 Wiley Periodicals, Inc.

Although most birds encounter large pressure variations during flight, motion of the middle ear components as a result of changing ambient pressure are not well known or described. In the present study, motion of the columella footplate and tympanic membrane (extrastapedius) in domestic chickens (Gallus gallus domesticus) under quasi-static pressure conditions are provided. Micro-CT scans were made of cadaveric heads of chickens under positive (0.25 kPa, 0.5 kPa, 1 kPa, and 1.5 kPa) and negative (-0.25 kPa, -0.5 kPa, -1 kPa, and -1.5 kPa) middle ear pressure. Both extrastapedius and columella footplate displacements show a non-linear S-shaped curve as a function of pressure indicating non-linear response characteristics of the middle ear components. The S-curve is also seen in mammals, but unlike in mammals, the lateral piston-like displacement of both the columella footplate and extrastapedius, which is caused by an increased middle ear pressure are smaller than the medial piston-like displacements, caused by a decreased middle ear pressure of the same magnitude. Columella footplate piston displacements are always smaller than the extrastapedius piston displacements, indicating the flexibility of the extracolumella. The cone-shape of the avian tympanic membrane with inverted apex in comparison to the mammalian tympanic membrane can cause the inverted shape of the pressure response curve. (C) 2018 Elsevier B.V. All rights reserved.

Objective: To compare stapes vibrations in different partial ossicular replacement prosthesis (PORP) applications. Methods: Stapedial vibrations were measured on fresh frozen human temporal bones with laser Doppler vibrometry. Eight different types of common ossiculoplasty methods were compared regarding recovery of stapes vibrations in relation with the normal ossicular chain. The PORPs were divided into three groups: 1) PORPs with the lateral contact only with the tympanic membrane, 2) PORPs with lateral contact only to the malleus handle, and 3) PORPs with lateral contact with both the malleus handle and the tympanic membrane. Results: The PORPs with lateral contact only to the malleus handle performed better than the PORPs with lateral contact to the tympanic membrane only at 2 kHZ, but the best recovery was found in the group with contact both to the malleus handle and the tympanic membrane. Conclusion: The best sound transmission might be achieved by placing a PORP in contact with both the tympanic membrane and the handle of the malleus.