Model Of Middle Ear Research Articles

Superior-semicircular-canal dehiscence: Effects of location, shape, and size on sound conduction

The effects of a superior-semicircular-canal (SSC) dehiscence (SSCD) on hearing sensitivity via the air-conduction (AC) and bone-conduction (BC) pathways were investigated using a three-dimensional finite-element (FE) model of a human middle ear coupled to the inner ear. Dehiscences were modeled by removing a section of the outer bony wall of the SSC and applying a zero-pressure condition to the fluid surface thus exposed. At each frequency, the basilar-membrane velocity, vBM, was separately calculated for AC and BC stimulation, under both pre- and post-dehiscence conditions. Hearing loss was calculated as the difference in the maximum magnitudes of vBM between the pre- and post-dehiscence conditions representing a change in hearing threshold. In this study, BC excitations were simulated by applying rigid-body vibrations to the model along the directions of the (arbitrarily defined) x, y, and z axes of the model.Simulation results are consistent with previous clinical measurements on patients with an SSCD and with results from earlier lumped-element electrical-circuit modeling studies, with the dehiscence decreasing the hearing threshold (i.e., increasing vBM) by about 35 dB for BC excitation at low frequencies, while for AC excitation the dehiscence increases the hearing threshold (i.e., decreases vBM) by about 15 dB. A new finding from this study is that the initial width (defined as the width of the edge of the dehiscence where the flow of the fluid-motion wave from the oval window meets it for the first time) on the vestibular side of the dehiscence has more of an effect on vBM than the area of the dehiscence. Analyses of dehiscence effects using the FE model further predict that changing the direction of the BC excitation should have an effect on vBM, with vBM being about 20 dB lower due to BC excitation parallel to the longitudinal direction of the BM in the hook region (the x direction) as compared to excitations in other directions (y and z). BC excitation in the x direction and with a ‘center’ dehiscence located midway along the length of the SSC causes a reduction in the anti-symmetric component of the fluid pressure across the BM, as compared to the other directions of BC excitation, which results in a decrease in vBM at high frequencies.This article is part of a Special Issue entitled “MEMRO 2012”.

Compensating for Deviant Middle Ear Pressure in Otoacoustic Emission Measurements, Data, and Comparison to a Middle Ear Model

Deviant middle ear pressure has a negative effect on the forward and backward transmission of stimulus and emissions through the middle ear. Resolving this deviant middle ear pressure is expected to lead to better middle ear transmission and, as a result of this, stronger otoacoustic emissions, which are better detectable. We investigated the effect of compensation o a deviant tympanic peak pressure on click-evoked otoacoustic emissions (CEOAEs). Second, we compared patient data to model predictions made by Zwislocki's middle ear model. University Medical Center. Fifty-nine children aged between 0.5 and 9 years (mean, 4.4 yr). Hearing investigations including CEOAE measurements at ambient and at compensated tympanic peak pressure (TPP). CEOAEs at ambient and compensated TPP. Compensation of TPP resulted in higher emission amplitudes below 2 kHz (increase of 8-11 dB). In addition, the compensated measurement showed an increased phase lag (up to one-fourth cycle). For ears with mild deviations of TPP, Zwislocki's model could describe these changes. Pressure compensation was well described by a compliance increase of the tympanic membrane, the malleus, and the incus. Compensating the ear canal pressure for negative tympanic peak pressure increased CEOAE amplitudes below 2 kHz and increased the phase lag. These changes can be predicted from an increase of the compliance of the tympanic membrane, incus, and malleus, as a consequence of the pressure compensation.

Nonlinear Approach to Modelling of Otosclerosis in a Human Middle Ear

The main aim of this work is to build simple but adequate model of middle ear which should work correctly in the range of frequencies which are important for the sake of speech recognition process. In the paper, a dynamic model of a middle ear is proposed as a three degree of freedom system where a malleus, an incus and stapes are modelled by lumped masses connected by visco-elastic joints. The influence of ligament stiffness coefficients on natural frequency of ossicles vibrations is investigated. The otosclerosis is modelled in two ways as stiffening of annular ligament caused by an increase of a linear stiffness coefficient or by a progressive nonlinear function. The nonlinear system is solved analytically near the first resonance zone with the help of the multiple scale method. Obtained results show that for selected input amplitude-frequency sets the output signal may exhibit subcritical bifurcations.

Perceptual audio features for emotion detection

Abstract In this article, we propose a new set of acoustic features for automatic emotion recognition from audio. The features are based on the perceptual quality metrics that are given in perceptual evaluation of audio quality known as ITU BS.1387 recommendation. Starting from the outer and middle ear models of the auditory system, we base our features on the masked perceptual loudness which defines relatively objective criteria for emotion detection. The features computed in critical bands based on the reference concept include the partial loudness of the emotional difference, emotional difference-to-perceptual mask ratio, measures of alterations of temporal envelopes, measures of harmonics of the emotional difference, the occurrence probability of emotional blocks, and perceptual bandwidth. A soft-majority voting decision rule that strengthens the conventional majority voting is proposed to assess the classifier outputs. Compared to the state-of-the-art systems including Munich Open-Source Emotion and Affect Recognition Toolkit, Hidden Markov Toolkit, and Generalized Discriminant Analysis, it is shown that the emotion recognition rates are improved between 7-16% for EMO-DB and 7-11% in VAM for "all" and "valence" tasks.

Effects of middle-ear disorders on power reflectance measured in cadaveric ear canals.

Reflectance measured in the ear canal offers a noninvasive method to monitor the acoustic properties of the middle ear, and few systematic measurements exist on the effects of various middle-ear disorders on the reflectance. This work uses a human cadaver-ear preparation and a mathematical middle-ear model to both measure and predict how power reflectance R is affected by the middle-ear disorders of static middle-ear pressures, middle-ear fluid, fixed stapes, disarticulated incudostapedial joint, and tympanic-membrane perforations. R was calculated from ear-canal pressure measurements made on human-cadaver ears in the normal condition and five states: (1) positive and negative pressure in the middle-ear cavity, (2) fluid-filled middle ear, (3) stapes fixed with dental cement, (4) incudostapedial joint disarticulated, and (5) tympanic-membrane perforations. The middle-ear model of Kringlebotn (1988) was modified to represent the middle-ear disorders. Model predictions are compared with measurements. For a given disorder, the general trends of the measurements and model were similar. The changes from normal in R, induced by the simulated disorder, generally depend on frequency and the extent of the disorder (except for the disarticulation). Systematic changes in middle-ear static pressure (up to 6300 daPa) resulted in systematic increases in R. These affects were most pronounced for frequencies up to 1000 to 2000 Hz. Above about 2000 Hz there were some asymmetries in behavior between negative and positive pressures. Results with fluid in the middle-ear air space were highly dependent on the percentage of the air space that was filled. Changes in R were minimal when a smaller fraction of the air space was filled with fluid, and as the air space was filled with more saline, R increased at most frequencies. Fixation of the stapes generally resulted in a relatively small low-frequency increase in R. Disarticulation of the incus with the stapes led to a consistent low-frequency decrease in R with a distinctive minimum below 1000 Hz. Perforations of the tympanic membrane resulted in a decrease in R for frequencies up to about 2000 Hz; at these lower frequencies, smaller perforations led to larger changes from normal when compared with larger perforations. These preliminary measurements help assess the utility of power reflectance as a diagnostic tool for middle-ear disorders. In particular, the measurements document (1) the frequency ranges for which the changes are largest and (2) the extent of the changes from normal for a spectrum of middle-ear disorders.

G100033 耳の伝音系のてこ作用を考慮したモデル化と振動特性の把握に関する検討

Sound is the vibration of air and humans recognize it in their ears. It is amplified in the external auditory meatus (E.A.M.) and vibrates the tympanic membrane (T.M.)- Finally, it is transmitted into the inner ear through the ossicle. Therefore, it's thought that human perception of sound is influenced by the vibration behavior of T.M. and ossicle. The purposes of this study are to create the middle ear model and to reveal the vibration characteristics of middle ear by numerical computing. In this study, we construct the simple middle ear model on the assumption that both the malleus and incus are rigid bodies and the stapes is single mass point. Also, the assumption on the malleus and incus as rigid bodies which have rotary motion, can express the motion of pry of the ossicle. In this report, we considered the vibration response of middle ear for various parameters. Moreover we also consider the vibration response of middle ear for white noise input to comprehend the frequency response of middle ear. Through this study, we confirm the natural frequency of the middle ear. Also we estimat the parameter which affects the vibration response. As a result, we indicate the possibility that the simple ear model can simulate the human's hearing system.

The ostrich middle ear for developing an ideal ossicular replacement prosthesis

The aim of the study was to investigate the validity of the avian middle ear model for researching the tympanoplasty mechanics. We studied the morphological details, acoustic transmission and quasi-static behavior of the ostrich tympano-ossicular system. The stained specimens of the ostrich middle ear were examined under a light microscope. The sound transfer function and quasi-static performance of the ostrich middle ear were evaluated using laser Doppler vibrometry. The application of pressure to the tip of the extracolumella causes a buckling movement of the ossicle between the cartilaginous and bony parts. Histologically, the intracolumellar connection can be identified as a junction zone between bone and hyaline cartilage. Sound conduction through the human middle ear is less effective than it is through the ostrich middle ear. The greatest difference (35 dB) was observed in the low-frequency region. Because the extracolumella bends, the medial displacements of the eardrum were not fully transmitted to the footplate. The amplitude of the ostrich columella footplate quasi-static medial displacements significantly exceeded that of the human footplate in both intact and reconstructed middle ears. The ostrich middle ear is a suitable model for designing total ossicular replacement implants. The main protective mechanism in the ostrich middle ear under quasi-static stress is a buckling movement of the extracolumella. The total ossicular prostheses of the new generation should contain an elastic element that allows an adaptation to greater quasi-static eardrum movements.

Evaluation des Dresdner Tympanoplastik Modells (DTM)

The training of microsurgical motor skills is essentiell for surgical education if the interests of the patient are to be safeguarded. In otosurgery the complex anatomy of the temporal bone and variations necessitate a special training before performing surgery on a patient. We therefore developed and evaluated a simplified middle ear model for acquiring first microsurgical skills in tympanoplasty.The simplified tympanoplasty model consists of the outer ear canal and a tympanic cavity. A stapes model is placed in projection of the upper posterior tympanic membrane quadrant at the medial wall of the simulated tympanic cavity. To imitate the annular ligament flexibility the stapes is fixed on a soft plastic pad. 41 subjects evaluated the model´s anatomical analogy, the comparability to the real surgical situation and the general model properties the using a special questionnaire.The tympanoplasty model was very well evaluated by all participants. It is a reasonably priced model and a useful tool in microsurgical skills training. Thereby, it closes the gap between theoretical training and real operation conditions.

Inertial Bone Conduction: Symmetric and Anti-Symmetric Components

Of the two pathways through which we hear, air conduction (AC) and bone conduction (BC), the fundamental mechanisms of the BC pathway remain poorly understood, despite their clinical significance. A finite element model of a human middle ear and cochlea was developed to gain insight into the mechanisms of BC hearing. The characteristics of various cochlear response quantities, including the basilar membrane (BM) vibration, oval-window (OW) and round-window (RW) volume velocities, and cochlear fluid pressures were examined for BC as well as AC excitations. These responses were tuned and validated against available experimental data from the literature. BC excitations were simulated in the form of rigid body vibrations of the surrounding bony structures in the x, y, and z orthogonal directions. The results show that the BM vibration characteristics are essentially invariant regardless of whether the excitation is via BC, independent of excitation direction, or via AC. This at first appeared surprising because the cochlear fluid pressures differ considerably depending on the excitation mode. Analysis reveals that the BM vibration responds only to the lower-magnitude anti-symmetric slow-wave cochlear fluid pressure component and not to the symmetric fast-wave pressure component, which dominates the magnitude of the total pressure field. This anti-symmetric fluid pressure is produced by the anti-symmetric component of the window volume velocities. As a result, the BM is effectively driven by the anti-symmetric component of the OW and RW volume velocities, irrespective of the type of excitation. Middle ear modifications that alter the anti-symmetric component of the OW and RW volume velocities corroborate this assertion. The current results provide further clarification of the mechanisms underlying Békésy's "paradoxical motion" concept.

Finite element model of human ear reconstruction through micro-computer tomography

Conclusions: The validated finite element model of human middle ear can be used as a tool in hearing loss research. Objective: To establish an accurate finite element model of the external ear canal and middle ear through micro-computer tomography and test its feasibility in the human. Methods: A fresh specimen of human temporal bone was scanned by micro-computer tomography. The finite element model was established based on the images, and then the simulation results were compared with published experimental data. Results: After a series of simulations were conducted, the simulated results were compatible with the published experimental data and this confirms the validation of the finite element model.

Realistic morphological 3-D model of the gerbil middle ear, including bone and soft tissue structures

Realistic morphological 3-D model of the gerbil middle ear, including bone and soft tissue structures

Reconstruction and exploration of virtual middle-ear models derived from micro-CT datasets

BackgroundMiddle-ear anatomy is integrally linked to both its normal function and its response to disease processes. Micro-CT imaging provides an opportunity to capture high-resolution anatomical data in a relatively quick and non-destructive manner. However, to optimally extract functionally relevant details, an intuitive means of reconstructing and interacting with these data is needed. Materials and methodsA micro-CT scanner was used to obtain high-resolution scans of freshly explanted human temporal bones. An advanced volume renderer was adapted to enable real-time reconstruction, display, and manipulation of these volumetric datasets. A custom-designed user interface provided for semi-automated threshold segmentation. A 6-degrees-of-freedom navigation device was designed and fabricated to enable exploration of the 3D space in a manner intuitive to those comfortable with the use of a surgical microscope. Standard haptic devices were also incorporated to assist in navigation and exploration. ResultsOur visualization workstation could be adapted to allow for the effective exploration of middle-ear micro-CT datasets. Functionally significant anatomical details could be recognized and objective data could be extracted. ConclusionsWe have developed an intuitive, rapid, and effective means of exploring otological micro-CT datasets. This system may provide a foundation for additional work based on middle-ear anatomical data.

Time-domain “wave” model of the human tympanic membrane

Middle ear models have been successfully developed for many years. Most of those are implemented in the frequency domain, where physical equations are more easily derived. This is problematic, however, when it comes to model non-linear phenomena, especially in the cochlea, and because a frequency-domain implementation may be less intuitive. This research explores a different approach, based on a time-domain implementation, fitted to impedance data. It is adapted from a previous work for the cat and focuses here on the human ear: volume velocity samples are distributed uniformly in space and updated periodically to simulate the propagation of the sound wave in the ear. The modeling approach is simple, yet it can quantitatively reproduce the major characteristics of the human middle ear transmission, and can qualitatively capture forward and reverse power transmission – a key feature of this time-domain implementation. These results suggest that complex, multi-modal propagation observed on the TM may not be critical to proper sound transmission along the ear. Besides, model predictions reveal that impedance and velocimetry measurements may be inconsistent with each other, hypothetically because velocimetry protocols could alter the middle ear.

Non-invasive measurements of intralabyrinthine pressure changes by electrocochleography and otoacoustic emissions

By varying the mechanical load on the stapes footplate, intralabyrinthine pressure (ILP) influences the stiffness of the middle ear and modifies its transfer function. This results in a characteristic phase shift of the otoacoustic emissions (OAEs) around 1 kHz [Buki, B., Avan, P., Lemaire, J.J., Dordain, M., Chazal, J., Ribari, O., 1996. Otoacoustic emissions: a new tool for monitoring intracranial pressure changes through stapes displacements. Hear. Res. 94, 125–139]. This finding provides non-invasive means of monitoring changes of ILP and indirectly of intracranial pressure. Yet the vulnerability of OAEs to sensorineural hearing loss excludes many patients from being monitored in this manner. Being dependent on the middle-ear transfer function, the phase of the cochlear microphonic potential (CM) around 1 kHz should also respond to ILP changes while being less affected by impaired hearing than OAEs. Here, normal volunteers were subjected to body tilt resulting in stepwise changes in their intracranial pressure and ILP. Their CM around 1 kHz was recorded by extratympanic electrocochleography and its dependence on body position was compared to that of distortion-product OAEs. The posture-induced CM changes were also monitored in ears with sensorineural deafness and impaired OAEs to assess the usefulness of CM in the presence of hearing impairment. Last, OAEs and CM were simultaneously monitored in gerbils during intracranial pressure changes brought about via an intracranial catheter. The phase and level shifts induced by body tilt in man and intracranial pressure changes in gerbils showed up both in distortion-product OAEs and CM with similar time courses. In normally-hearing subjects, the mean phase shifts reached 16.3° for CM and 41.6° for OAEs, and CM remained large enough in hearing-impaired subjects for ILP to be monitored. The ratio of about two of OAEs to CM phase shifts matched the prediction of middle-ear models allowing for the fact that CM does not travel back through the middle ear while OAEs do. It follows that CM phase around 1 kHz provides non-invasive access to ILP changes even if OAEs cannot be measured due to sensorineural hearing loss.

Tympanometric experiments on retracted ear drums – does tympanometry reflect the true middle ear pressure?

Conclusions: Tympanometry in ears with retracted or partially atelectatic tympanic membranes does not reflect the true middle ear (ME) pressure. The position of the tympanogram peak depends on the size of a retraction pocket and the remaining ME gas volume. Thus tympanometry in such cases cannot be used for measurements of ME pressure. Objective: To prove the hypothesis that tympanometry in ears with retraction pockets or atelectasis does not measure ME pressure correctly. Materials and methods: Tympanometry was performed in a simplified artificial ME model, in which different ‘tympanic membranes’ with pockets could be integrated. Results: We found a shift of the tympanogram peaks, either towards negative or positive pressures, depending on the position of the pocket: in case of an ‘inward’ direction (towards the ME like a retraction pocket) the peak was in the negative pressure range, in case of an ‘outward’ direction (bulging into the ear canal) the shift was towards positive pressures. The shift increased with decreasing volume behind the tympanic membrane. The effect cannot be simply be explained by hysteresis but by the air ‘cushion’ that is ‘trapped’ behind the membrane, limiting its excursions during the tympanometric sweep.

Design of Floating Mass Type Piezoelectric Actuator for Implantable Middle Ear Hearing Devices

To overcome some of the problems inherent in conventional hearing aids such as low gain at high frequencies due to acoustic feedback, discomfort in occlusion of the external ear canal and so on, implantable middle ear hearing devices (IMEHDs) have been developed over the past two decades. For such kinds of IMEHDs, this paper presents the design of a floating mass piezoelectric actuator using a PMN-30%PT stack as a new type of vibrator. The proposed piezoelectric actuator consists of only three components of a piezoelectric stack, a metal case and a clamp. For the purpose of aiding the design of this actuator, a coupling biomechanics model of human middle ear and the piezoelectric actuator was constructed. This model was built based on a complete set of computerized tomography section images of a healthy volunteer’s left ear by reverse engineering technology. The validity of this model was confirmed by comparing the motion of the tympanic membrane and stapes footplate obtained by this model with published experimental measurements on human temporal bones. It is shown that the designed actuator can be implanted on the incus long process by a simple surgical operation, and the stapes footplate displacement by its excitation at 10.5 V root-mean-square(RMS) voltage was equivalent to that from acoustic stimulation at 100 dB sound pressure level(SPL), which is adequate stimulation to the ossicular chain. The corresponding power consumption is 0.04 mW per volt of excitation at 1 kHz, which is low enough for the transducer to be used in an implantable middle ear device.

Free Bioverit ® II Implants Coated with a Nanoporous Silica Layer in a Mouse Ear Model — A Histological Study

The objective of this study is to evaluate the suitability of a mouse middle ear model for testing ossicular replacement materials. Twenty-four BALB/c mice are implanted with the bioglass-ceramic Bioverit II which is coated with a silica-nanostructure or with plain Bioverit II as a control. After 2, 6, and 12 weeks, 4 mice per group are sacrificed and both complete petrous bones are analyzed histologically. All implants revealed in situ an incipient growth of thin connective tissue layers over the surface, followed by a spreading of epithelial cells. The osseogenic response which is increasing with time is more intense in the coated Bioverit II specimens. The absence of inflammatory cells suggests an excellent biocompatibility of the silica nano structure. As the results are comparable to a study with the same materials in rabbits, the mouse model described is highly suitable for evaluation of new ossicular replacement materials. Additionally, by gene expression analysis a more detailed insight into cellular interactions of the middle ear is offered.

A nonlinear finite-element model of the newborn middle ear

A three-dimensional static nonlinear finite-element model of a 22-day-old newborn middle ear is presented. The model includes the tympanic membrane (TM), malleus, incus, and two ligaments. The effects of the middle-ear cavity are taken into account indirectly. The geometry is based on a computed-tomography scan and on the published literature, supplemented by histology. A nonlinear hyperelastic constitutive law is applied to model large deformations. The middle-ear cavity and the Young's modulus of the TM have significant effects on TM volume displacements. The TM volume displacement and its nonlinearity and asymmetry increase as the middle-ear cavity volume increases. The effects of the Young's moduli of the ligaments and ossicles are found to be small. The simulated TM volume changes do not reach a plateau when the pressure is varied to either -3 kPa or +3 kPa, which is consistent with the nonflat tails often found in tympanograms in newborns. The simulated TM volume displacements, by themselves and also together with previous ear-canal model results, are compared with equivalent-volume differences derived from tympanometric measurements in newborns. The results suggest that the canal-wall volume displacement makes a major contribution to the total canal volume change, and may be larger than the TM volume displacement.

A study on the input-output function of a nonlinear cochlear transmission-line model with the function of an outer hair cell model

A nonlinear cochlear transmission-line model with the physiological function of an outer hair cell (OHC) model is presented to investigate how OHCs produce the nonlinearity in the input-output (IO) functions of cochlear filtering. As the physiological function of the OHC model, the pressure produced by the somatic motility of the OHCs was studied. The somatic motility is induced by the transducer currents that change with the displacement of the hair bundle. The pressure produced by the OHC model can be linearly approximated by the amount of current. The proposed model is comprised of a middle ear model and a cochlear transmission-line model, which includes a basilar membrane and lymph fluid model, a tectorial membrane model, hair bundles model, and the OHC model. The model’s parameters were set as estimates for a human obtained from animal data. In simulation results, this model could account for the IO functions of cochlear filtering obtained from both physiological and psychological experiments. These results suggest that the somatic motility of the OHCs, which depends on the transducer currents, produces the nonlinearity in the IO functions of cochlear filtering.

Calculation of inertial properties of the malleus-incus complex from micro-CT imaging

The middle ear bones are the smallest bones in the human body and are among the most complicated functionally. These bones are located within the temporal bone making them difficult to access and study. We use the micro-CT imaging modality to obtain quantitative inertial properties of the MIC (malleus-incus complex), which is a subcomponent of the middle ear. The principal moment of inertia of the malleus along the superior-inferior axis (17.3 ± 2.3 mg/mm3) is lower by about a factor of six in comparison to the anterior-posterior and lateral-medial axes. For the incus, the principal moment of inertia along the superior-inferior axis (35.3 ± 6.9 mg/mm3) is lower by about a factor of two than for the other two axes. With the two bones combined (MIC), the minimum principal moment of inertia (132.5 ± 18.5 mg/mm3) is still along the superior-inferior axis but is higher than for the individual bones. The superior-inferior axis inertia is lower by a factor of 1.3 than along the anterior-posterior axis and is lower by a factor 2 along the lateral-medial axis. Values for inertia of the MIC show significant individual differences in three human ears measured, suggesting that middle ear models should be based on individual anatomy. Imaging by micro-CT scanner is a nondestructive modality that provides three-dimensional volume information about middle ear bones at each stage of manipulation with resolution down to 10μm. In this work extraneous tissue is removed to obtain a sufficiently small specimen. However, advances in imaging hold promise that this capability will be available for in vivo measurements.