Ear Biomechanics Research Articles

Dynamic X-ray Microtomography vs. Laser-Doppler Vibrometry: A Comparative Study.

There are challenges in understanding the biomechanics of the human middle ear, and established methods for studying this system show significant limitations. In this study, we evaluate a novel dynamic imaging technique based on synchrotron X-ray microtomography designed to assess the biomechanical properties of the human middle ear by comparing it to laser-Doppler vibrometry (LDV). We examined three fresh-frozen temporal bones (TB) using dynamic synchrotron-based X-ray microtomography for 256 Hz and 512 Hz, stimulated at 110 dB and 120 dB SPL. In addition, we performed measurements on these TBs using 1D LDV, a well-established method. The normalized displacement values (μm/Pa) at the umbo and the posterior crus of the stapes are consistent or within 5-10 dB differences between all LDV and dynamic microtomography measurements and previously reported literature references. In general, the overall behavior is similar between the two measurement techniques. In conclusion, our results demonstrate the suitability of dynamic synchrotron-based X-ray microtomography in studying the middle ear's biomechanics. However, this study shows that better standardization regarding acoustic stimulation and measurement points is needed to better compare the two measurement techniques.

Application of finite element model of middle ear in the study of the middle ear biomechanics in normal and diseased states

Aim: The aim of this study was to create a three-dimensional model of the middle ear by finite element (FE) analysis, using measurements performed on human and cadaveric high-resolution computed tomography (HRCT) temporal bone, and to study the biomechanics in diseased conditions. Materials and Methods: This observational, cross-sectional study was conducted in Acharya Vinoba Bhave Rural Hospital, Sawangi, Meghe, Maharashtra, in the Department of Otorhinolaryngology. The first step of FE modeling approach comprised computer-aided geometric model incorporating the static dimensions from human and cadaveric temporal bones and dynamic dimensions from prepublished data. HRCT Scans of both sets of temporal bones were performed with 0.5 mm cuts, and measurements of the ossicles, middle ear, and tympanic membrane were taken. The cadaveric temporal bones were drilled, the ossicles dissected out and measured using HRCT as well as vernier calipers. This was followed by construction of the working FE model and application of this FE model for studying middle ear biomechanics in normal and diseased states. Results: The mean measurements of ossicles were calculated, and the movement of tympanic membrane was maximum at the site of umbo and stapes footplate, whereas minimum movement was within the ossicles. Larger peak-to-peak displacement was seen at 1000 Hz to 3000 Hz frequency. Our results suggest that FE model can prove beneficial in the study of middle ear biomechanics. Conclusion: The changes in the tympanic membrane movement in diseased state have been compared to normal ear and can be applied to reconstructed ears. FE analysis can be used to study the effect of material properties of various graft materials used in tympanomastoidectomy.

Inner ear biomechanics reveals a Late Triassic origin for mammalian endothermy.

Endothermy underpins the ecological dominance of mammals and birds in diverse environmental settings1,2. However, it is unclear when this crucial feature emerged during mammalian evolutionary history, as most of the fossil evidence is ambiguous3-17. Here we show that this key evolutionary transition can be investigated using the morphology of the endolymph-filled semicircular ducts of the inner ear, which monitor head rotations and are essential for motor coordination, navigation and spatial awareness18-22. Increased body temperatures during the ectotherm-endotherm transition of mammal ancestors would decrease endolymph viscosity, negatively affecting semicircular duct biomechanics23,24, while simultaneously increasing behavioural activity25,26 probably required improved performance27. Morphological changes to the membranous ducts and enclosing bony canals would have been necessary to maintain optimal functionality during this transition. To track these morphofunctional changes in 56 extinct synapsid species, we developed the thermo-motility index, a proxy based on bony canal morphology. The results suggest that endothermy evolved abruptly during the Late Triassic period in Mammaliamorpha, correlated with a sharp increase in body temperature (5-9 °C) and an expansion of aerobic and anaerobic capacities. Contrary to previous suggestions3-14, all stem mammaliamorphs were most probably ectotherms. Endothermy, as a crucial physiological characteristic, joins other distinctive mammalian features that arose during this period of climatic instability28.

Validated Ossicular Measurements on High-Resolution Computed Tomography (CT) in Live and Cadaveric Temporal Bones.

ObjectiveThe present study was undertaken to study the utility of high-resolution computed tomography (HRCT) temporal bone in live patients for providing the parameters of ossicular dimensions (OD), using standard assessment protocols, devised by the authors, with regard to the plane of CT scans and axes of measurement of ossicles.MethodsThis observational study was conducted from January 2021 to February 2022 at Acharya Vinoba Bhave Rural Hospital, Sawanghi, Meghe, Maharashtra, India, in the Department of Otorhinolaryngology and Department of Radiodiagnosis. HRCT scan was performed on temporal bones, 10 in live subjects with no otological complaints and 10 in cadaveric temporal bones. HRCT was also performed for all three ossicles after dissecting them out from the respective cadaveric temporal bones. Measurements of OD were taken using Universalmednet Software and vernier calipers and compared with published anatomic data.ResultsThe measurements taken using HRCT scans of the live subject and cadaveric bone as well as the ossicles taken using calipers fall within the range of published studies. Slight variation is seen in the measurements of stapes and incus, stapes total height is 3.17mm, less than 3.3. Conventional HRCT temporal bone in live patients when performed under set circumstances can be adopted as a standard method for measurement of ossicular sizes for the generation of normative data for different races, ethnicity and sex.ConclusionThe results of our study can have implications in terms of translational research as the measurements obtained can help in better understanding of middle ear biomechanics, prosthesis designing, developing ideal tympanoplasty methods in terms of size, shape and placement of autograft.

Polyharmonic Vibrations of Human Middle Ear Implanted by Means of Nonlinear Coupler.

This paper presents a possibility of quasi-periodic and chaotic vibrations in the human middle ear stimulated by an implant, which is fixed to the incus by means of a nonlinear coupler. The coupler represents a classical element made of titanium and shape memory alloy. A five-degrees-of-freedom model of lumped masses is used to represent the implanted middle ear for both normal and pathological ears. The model is engaged to numerically find the influence of the nonlinear coupler on stapes and implant dynamics. As a result, regions of parameters regarding the quasi-periodic, polyharmonic and irregular motion are identified as new contributions in ear bio-mechanics. The nonlinear coupler causes irregular motion, which is undesired for the middle ear. However, the use of the stiff coupler also ensures regular vibrations of the stapes for higher frequencies. As a consequence, the utility of the nonlinear coupler is proven.

Peaks between peaks: Comparative intra-ear correlations in spontaneous otoacoustic emissions

Spontaneous otoacoustic emissions (SOAEs) are a key facet of modern models of inner ear biomechanics, as the phenomenon provides crucial insight into the notion of the “active ear.” Manifesting as an idiosyncratic array of spectral peaks unique to a given ear, individual SOAE peaks have nonstationary properties (e.g., amplitude and frequency modulations). Further, it has been demonstrated that interpeak relations between these “AM” and “FM” properties can be correlated, indicative of coupling of the underlying generation mechanisms. This study takes a comparative approach to characterizing these correlations in a wide variety of species exhibiting SOAEs (humans, birds, lizards) despite relatively disparate inner ear morphologies. Initial results are consistent with previous reports (e.g., van Dijk and Wit, 1990, 1998) in that SOAE interpeak correlations for a given ear are themselves idiosyncratic: Sometimes peaks (adjacent or not) exhibit correlated (positive or negative) AM and/or FM fluctuations with delays up to the order of milliseconds (typically longer for humans, shorter for lizards), while sometimes no correlation is observed. We explore implications for how such may constrain models treating the inner ear as a spatially distributed tonotopic system (e.g., various biophysical roles for coupling).

Ethanol infiltration into the stapedio-vestibular joint reduces low-frequency vibration of the ossicular chain and round window membrane in the guinea pig

Background: The synovial stapedio-vestibular joint (SVJ), which serves as a bridge between the stape and oval window, can be found in guinea pigs and most human adults. Unlike the fibrous SVJs in other animals, the contribution of the synovial SVJ to middle ear sound transmission remains unknown.Aims/objectives: In this study, we investigate whether sclerosis of the synovial SVJ contributes to frequency-dependent vibration of the ossicular chain and round window membrane (RWM).Materials and methods: A model of SVJ sclerosis model was established in the guinea pig using 75% ethanol. A laser Doppler vibrometer was then used to measure vibrations of the RWM and the long process of the incus (LPI) under pure tone sound stimulations of 0.25–16 kHz. The influence of SVJ sclerosis was analysed by comparing structural vibration displacement between the normal and sclerosis groups.Results: Both LPI and RWM vibrations significantly decreased at low frequencies after infiltration of ethanol, which caused SVJ sclerosis.Conclusions: SVJ sclerosis reduces low-frequency vibration of the ossicular chain and RWM in the guinea pig, which indicates that the synovial SVJ is vital to low-frequency sound transmission in the middle ear.Significance: Providing useful data for further research regarding middle ear biomechanics.

Insect ear biomechanics: Passive and active processes that can inspire acoustic sensors

Biological systems provide an incredible wealth of archetypes that have emerged through evolutionary processes. Hearing organs are a good example of how different solutions, and adaptions, across different animal taxa, can often converge to solve similar sensory problems. Hearing has evolved independently multiple times across the insects, and the diversity of these biological solutions therefore provides a wealth of inspiration for the creation of novel acoustic sensors. Some biological solutions can be considered as purely passive mechanical constructs that accomplish some processing of the incoming sound. This talk will consider examples of this, including the frequency discrimination of the locust ear, and the directionality and wideband response of different moth ears. Several insects also display active hearing processes, whereby energy is used to actively change the hearing response, bearing some similarity to the processes found in the mammalian inner ear. This talk will thus discuss how some moths actively tune their ear, and how the mosquito ear actively utilizes gain and compression. Finally, the talk will discuss some examples of different acoustic sensors from the University of Strathclyde that take inspiration from these passive and active biological processes.

Surface strain-field determination of tympanic membrane using 3D-digital holographic interferometry

In order to increase the understanding of soft tissues mechanical properties, 3D Digital Holographic Interferometry (3D-DHI) was used to quantify the strain-field on a cat tympanic membrane (TM) surface. The experiments were carried out applying a constant sound-stimuli pressure of 90dB SPL (0.632Pa) on the TM at 1.2kHz. The technique allows the accurate acquisition of the micro-displacement data along the x, y and z directions, which is a must for a full characterization of the tissue mechanical behavior under load, and for the calculation of the strain-field in situ. The displacements repeatability in z direction shows a standard deviation of 0.062µm at 95% confidence level. In order to realize the full 3D characterization correctly the contour of the TM surface was measured employing the optically non-contact two-illumination positions contouring method. The x, y and z displacements combined with the TM contour data allow the evaluation its strain-field by spatially differentiating the u(m,n), v(m,n), and w(m,n) deformation components. The accurate and correct determination of the TM strain-field leads to describing its elasticity, which is an important parameter needed to improve ear biomechanics studies, audition processes and TM mobility in both experimental measurements and theoretical analysis of ear functionality and its modeling.

Holographic otoscope using dual-shot-acquisition for the study of eardrum biomechanical displacements

Recently an optoelectronic holography system was deployed in the clinic with the purpose of quantifying the tympanic membrane (TM) displacements of various mammal species, the objective being the understanding of their middle ear biomechanics. The optoelectronic holography system has an in-line configuration where the data gathered is decoded using lensless digital holography with the Fresnel approximation. This paper presents quantitative data obtained from an acoustically excited postmortem chinchilla's TM. To achieve this we used a robust customized windowed unwrapping method to unwrap the noisy optical phase obtained by subtracting phase maps of two recorded holograms and the results were compared with those obtained when using the unwrapping branch-cut algorithm. Additionally, phase maps obtained by the phase-stepping technique were compared applying both unwrapping methods. For in vivo applications particular emphasis is made on post-processing dual-shot-acquisition of holograms as one of various acquisition strategies and algorithms to diminish measurement error due to heartbeat, breathing, and patient's head motion as well as environment induced mechanical disturbances present in a noncontrolled environment, such as in a clinic. By recording only two holograms representing a stationary and deformed state of eardrum, respectively, we can increase the acquisition speed of the camera used to record faster events happening on the TM surface.

Dynamic Analysis of Human Ear during Sound Transmission

The aim of the present research is to simulate dynamic behavior of the human auditoria peripherals during sound transmission using the equivalent six-degrees-of-freedom lumped parameter mathematical model. Transmissibility analysis was employed to get a better insight into the sound transmission from tympanic membrane to malleus, incus, stapes, and cochlea. Furthermore, transmissibility from each member to corresponding adjacent member was carried out to functional analysis of the human ear. Simulation study illustrated that the results are in agreement with the experimental results published in the literature, and the proposed model provides more information in the dynamic analysis of middle ear biomechanics.

Computer Aided Modeling of Human Mastoid Cavity Biomechanics Using Finite Element Analysis

The aim of the present study was to analyze the human mastoid cavity on sound transmission using finite element method. Pressure distributions in the external ear canal and middle ear cavity at different frequencies were demonstrated. Our results showed that, first, blocking the aditus improves middle ear sound transmission in the 1500- to 2500-Hz range and decreases displacement in frequencies below 1000 Hz when compared with the normal ear. Second, at frequencies lower than 1000 Hz, the acoustic pressures were almost uniformly distributed in the external ear canal and middle ear cavity. At high frequencies, higher than 1000 Hz, the pressure distribution varied along the external ear canal and middle ear cavity. Third, opening the aditus, the pressures difference in dB between the middle ear cavity and external ear canal were larger than those of the closed mastoid cavity in low frequency (<1000 Hz). Finally, there was no significant difference in the acoustic pressure between the oval window and round window is noted and increased by 5 dB by blocking the aditus. These results suggest that our complete FE model including the mastoid cavity is potentially useful and can provide more information in the study of middle ear biomechanics.

Implantable hearing aids

The aim of this article is to give readers a general overview of the concepts involved in the latest generation of implantable hearing aids. A section on ear biomechanics has also been included to familiarize readers with the basic concepts involved. These devices have been developed over the last 20 years, driven by problems with conventional hearing aids and by advances in the understanding of middle-ear mechanics. The use of technology borrowed from cochlear implants has enabled the first generation of fully implantable aids to be trialled. The author examines the theoretical advantages and disadvantages of implantable hearing aids over conventional aids and then reviews the technology and clinical results of a range of devices that have been trialled.

Three‐Dimensional Reconstruction and Modeling of Middle Ear Biomechanics by High‐Resolution Computed Tomography and Finite Element Analysis

To present a systematic and practical approach that uses high-resolution computed tomography to derive models of the middle ear for finite element analysis. This prospective study included 31 subjects with normal hearing and no previous otologic disorders. Temporal bone images obtained from 15 right ears and 16 left ears were used for evaluation and reconstruction. High-resolution computed tomography of temporal bone was performed using simultaneous acquisition of 16 sections with a collimated slice thickness of 0.625 mm. All images were transferred to an Amira visualization system for three-dimensional reconstruction. The created three-dimensional model was translated into two commercial modeling packages, Patran and ANSYS, for finite element analysis. The characteristic dimensions of the model were measured and compared with previously published histologic section data. This result confirms that the geometric model created by the proposed method is accurate except that the tympanic membrane is thicker than when measured by the histologic section method. No obvious difference in the geometrical dimension between right and left ossicles was found (P > .05). The three-dimensional model created by finite element method and predicted umbo and stapes displacements are close to the bounds of the experimental curves of Nishihara's, Huber's, Gan's, and Sun's data across the frequency range of 100 to 8000 Hz. The model includes a description of the geometry of the middle ear components and dynamic equations of vibration. The proposed method is quick, practical, low-cost, and, most importantly, noninvasive as compared with histologic section methods.

Three-dimensional modeling of middle ear biomechanics and its applications.

This study investigated whether combined technologies of finite element (FE) analysis and three-dimensional reconstruction of human temporal bones could be used to construct a computational model, useful in describing normal and pathologic middle ear sound conduction. FE models for biologic systems have been used in ear biomechanics. Three-dimensional reconstructions have also been made, but not in combination with FE modeling and laser interferometry measuring of human temporal bones. Furthermore, an FE model for the human middle ear with its ossicular attachments has not been reported on the basis of temporal bone histologic sections and morphometric reconstruction, to the authors' best knowledge. Because of the size, variability, and complexity of the middle ear, accurate morphologic data and boundary conditions are necessary for accurate FE modeling. A fresh temporal bone was decalcified, embedded in celloidin, sectioned and stained, scanned, and digitized, and the normal middle ear was reconstructed. The histologic sections were used to construct a computer-aided design model with ligaments, muscles, and tendons as boundary conditions. The data thus obtained were converted into an FE mechanical model that was validated by comparison with displacements obtained by laser Doppler interferometry on 17 fresh human temporal bones. An FE model was generated, demonstrating dynamic behavior that moderately approximated the laser interferometric data from human temporal bones receiving 90-dB sound pressure level auditory frequencies at the tympanic membrane. Accurate FE modeling, incorporating both morphometric and interferometric performance data, predicted both normal and pathologic mechanical performance of the human ossicular chain.

Sequelae of Secretory Otitis Media: Changes in Middle Ear Biomechanics

Gaihede M, Lildholdt T, Lunding J. Sequelae of secretory otitis media: changes in middle ear biomechanics. Acta Otolaryngol (Stockh) 1997; 117: 382-389.A new method previously introduced investigating the pressure-volume relationship of the middle ear system describes dynamic mechanical properties of the system: the variables measured are hysteresis, compliance, and Pec0 expressing the zero position of the tympanic membrane. The present study investigates the mechanical properties in 69 adolescents treated with ventilation tubes during childhood due to secretory otitis media. The tympanic membranes displayed various degrees of atrophy, sclerosis, and retraction of the pars flaccida. Atrophy was quantitatively related to decreasing hysteresis and increasing compliance, while myringosclerosis showed opposite effects. Pec0 was significantly lower for the group of former secretory otitis media than for normals (p < 0.001). This reflects a retraction pattern of the tympanic membrane, which may be explained by a low opening pressure of the eustachian tube or previous pressure load of the drum. Signs of retraction were not found by tympanometry. Treatment with ventilation tubes was associated with a dramatic increase of tympanic membrane pathology (66%) compared to untreated ears (12%), as assessed by otomi-croscopy (p < 0.001). However, these changes specific to treatment were not found in the corresponding mechanical variables of the middle ear system, as the effects of combined atrophy and myringosclerosis tend to counterbalance.

Physical properties of fluids and structures of vestibular apparatus of the pigeon.

ARTICLESPhysical properties of fluids and structures of vestibular apparatus of the pigeonKE Money, L Bonen, JD Beatty, LA Kuehn, M Sokoloff, and RS WeaverKE Money, L Bonen, JD Beatty, LA Kuehn, M Sokoloff, and RS WeaverPublished Online:01 Jan 1971https://doi.org/10.1152/ajplegacy.1971.220.1.140MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByEvolution of thermoregulation as told by ear20 July 2022 | Nature, Vol. 607, No. 7920Inner ear biomechanics reveals a Late Triassic origin for mammalian endothermy20 July 2022 | Nature, Vol. 607, No. 7920Differential Activation of Canal and Otolith Afferents by Acoustic Tone Bursts in Rats4 April 2022 | Journal of the Association for Research in Otolaryngology, Vol. 23, No. 3Update on Nystagmus and Other Ocular OscillationsJournal of Clinical Neurology, Vol. 17, No. 3Positional alcohol nystagmus and serum osmolality: New insights into dizziness associated with acute alcohol intoxicationMedical Hypotheses, Vol. 138Persistent geotropic direction‐changing positional nystagmus with a null plane: The light cupula25 October 2013 | The Laryngoscope, Vol. 124, No. 1Anatomy of the Vestibular SystemHistological preparation of developing vestibular otoconia for scanning electron microscopyJournal of Neuroscience Methods, Vol. 125, No. 1-2Modeling the relation between head orientations and otolith responses in humansHearing Research, Vol. 173, No. 1-2A mathematical analysis of the peripheral auditory system mechanics in the goldfish (Carassius auratus)The Journal of the Acoustical Society of America, Vol. 108, No. 3New insights into positional alcohol nystagmus using three-dimensional eye-movement analysis1 January 2001 | Annals of Neurology, Vol. 45, No. 2The Papilla Neglecta of Turtles: A Detector of Head Rotations with Unique Sensory Coding Properties1 June 1998 | The Journal of Neuroscience, Vol. 18, No. 11Neuere Aspekte des vestibulookulären ReflexesOtolith Biomechanics1 July 1988Stabilizing gaze reflexes in the pigeon (Columba livia)Experimental Brain Research, Vol. 69, No. 3Effect of spaceflight on thresholds of perception of angular and linear motionArchives of Oto-Rhino-Laryngology, Vol. 244, No. 3The Influence of Semicircular Canal Morphology on Endolymph Flow Dynamics: An Anatomically Descriptive Mathematical Model8 July 2009 | Acta Oto-Laryngologica, Vol. 103, No. 1-2Investigations into the Cause of Canal Paresis in Meniere's Disease4 January 2009 | The Laryngoscope, Vol. 96, No. 11Mechanics of the otolith organ-dynamic responseAnnals of Biomedical Engineering, Vol. 14, No. 3Some hydrodynamic properties of the posterior canal in the frog labyrinth related to neuronal responsesNeuroscience Letters, Vol. 66, No. 3Sense OrgansReferences8 July 2009 | Acta Oto-Laryngologica, Vol. 100, No. sup427The high frequency limit of the fundamental vestibulo-ocular reflexArchives of Oto-Rhino-Laryngology, Vol. 239, No. 3Dimensional analysis and dynamic response characterization of mammalian peripheral vestibular structuresAmerican Journal of Anatomy, Vol. 169, No. 3Semicircular Canals: Measurement of Endolymphatic and Cupular Displacements at Threshold8 July 2009 | Acta Oto-Laryngologica, Vol. 93, No. 1-6The Influence of Duct and Utricular Morphology on Semicircular Canal ResponseA Species Comparison of Linear and Nonlinear Transfer Characteristics of Primary Afferents Innervating the Semicircular CanalNeuromorphometric features and dimensional analysis of the vestibular end organ in the little brown bat (Myotis lucifugus)The Journal of Comparative Neurology, Vol. 192, No. 4Displacement configuration of semicircular canal cupulaeNeuroscience, Vol. 4, No. 12Displacement of the semicircular canal cupula during sinusoidal rotationNeuroscience, Vol. 4, No. 12Cupula Motion in the Semicircular Canal of the Skate, RAJA ERINACEA An Experimental Investigation8 July 2009 | Acta Oto-Laryngologica, Vol. 87, No. 3-6The Vestibular System: Basic Biophysical and Physiological MechanismsSemicircular canal radii of curvature (R) in cat, guinea pig and manJournal of Morphology, Vol. 151, No. 1Semicircular duct and ampulla dimensions in cat, guinea pig and manJournal of Morphology, Vol. 151, No. 1Sense OrgansA scanning electron microscopic study of the morphology and geometry of neural surfaces and structures associated with the vestibular apparatus of the pigeonThe Journal of Comparative Neurology, Vol. 159, No. 2THE PERIPHERAL NEURONA computer program for graphical and iterative fitting of low and high order transfer functions to biological dataComputer Programs in Biomedicine, Vol. 4, No. 1The sensura neglecta in the pigeon: A scanning electron and light microscope studyThe Journal of Comparative Neurology, Vol. 154, No. 3Heavy water nystagmus and effects of alcoholNature, Vol. 247, No. 5440MECHANORECEPTIONThe Role Of The Perilymph In Semicircular Canal Stimulation8 July 2009 | Acta Oto-Laryngologica, Vol. 75, No. 2-6The vestibular system of the owlComparative Biochemistry and Physiology Part A: Physiology, Vol. 42, No. 2Physiological Range of Pressure Difference and Cupula Deflections in the Human Semicircular Canal: Theoretical ConsiderationsThe Physiological Range of Pressure Difference and Cupula Deflections in the Human Semicircular Canal: Theoretical Considerations8 July 2009 | Acta Oto-Laryngologica, Vol. 74, No. 1-6 More from this issue > Volume 220Issue 1January 1971Pages 140-147 Copyright & PermissionsCopyright © 1971 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1971.220.1.140PubMed5312607History Published online 1 January 1971 Published in print 1 January 1971 Metrics