1,720,967 research outputs found
Model-oriented Review and Multi-Body Simulation of the Ossicular Chain of the Human Middle Ear
No full textThe ossicular chain of the human middle ear has a key role in sound conduction since it transfers vibrations from the tympanic membrane to the cochlea, connecting the outer and the inner part of the hearing organ.
This study reports firstly a description of the main anatomical features of the middle ear to introduce a detailed survey of its biomechanics, focused on model development, with a collection of geometric, inertial and mechanical/material parameters. The joint issues are particularly discussed from the perspective of developing a model of the middle ear both explanatory and predictive. Such a survey underlines the remarkable dispersion of data, due also to the lack of a standardization of the experimental techniques and conditions.
Subsequently, a 3D multi-body model of the ossicular chain and other structures of the middle ear is described. Such an approach is justified as the ossicles were proven to behave as rigid bodies in the human hearing range and was preferred to the more widely used finite element one as it simplifies the model development and improves joint modeling. The displacement of the umbo (a reference point of the tympanic membrane) in the 0.3-6 kHz frequency range was defined as input of the model, while the stapes footplate displacement as output. A parameter identification procedure was used to find parameter values for reproducing experimental and numerical reference curves taken from the literature. This simple model might represent a valid alternative to more complex models and might provide a useful tool to simulate pathological/post-surgical/post-traumatic conditions and evaluate ossicular replacement prostheses
Comparison of finite element formulations for sound transmission modeling of the outer ear
No full textThe work described in this paper is part of a broader research activity on the development of a
virtual ear. The present study focuses on the tympanic membrane and auditory canal
modeling, which are main components in sound transmission.
The standard finite element method (FEM) and alternative methods (the spectral method
and the generalized finite element method) suitable for modeling sound propagation at high
frequencies were applied. Two domains (fluid and structural) for the auditory canal and the
tympanic membrane, respectively, were considered in order to evaluate the coupling of
different methods and to apply a fluid-structure interaction formulation.
The analysis results on an anatomical finite element model, which include pressure
distribution in the auditory canal and displacement distribution and frequency response of the
tympanic membrane, confirm experimental and theoretical data reported in the literature.
The spectral and generalized FE methods were implemented and applied to approximated
three-dimensional models of the outer ear. The validation of such methods with standard FEM
simulation at increasing mesh density shows their computational advantages in terms of
reduced mesh density required for accurate results
Integrazione di metodi FE avanzati per l'analisi fluido-strutturale dell'orecchio
No full textL’obiettivo della ricerca in cui si inserisce questo lavoro è lo sviluppo di un modello della percezione uditiva umana. Il presente studio è dedicato allo sviluppo di modelli del canale uditivo e della membrana timpanica, componenti fondamentali per la trasmissione del suono.
Sono stati applicati metodi ad elementi finiti classici (FEM) e metodi idonei per la simulazione della propagazione di onde acustiche ad alta frequenza nel canale uditivo. In questo lavoro, l’attenzione è stata rivolta principalmente al metodo generalizzato ad elementi finiti (GFEM) (combinazione del FEM standard e del metodo basato sulla partizione dell’unità (PU(FE)M)). Il problema, formulato con due domini (fluido e strutturale) rispettivamente per il canale uditivo e la membrana timpanica, ha permesso di valutare l’interfacciamento tra i metodi e l’applicazione di una formulazione di interazione fluido-strutturale (FSI).
I risultati ottenuti, in termini di distribuzione di pressione nel canale uditivo e di spostamento e di risposta in frequenza della membrana timpanica dello spostamento dell’umbo, , distribuzione di spostamento e di pressione rispettivamente nella membrana timpanica e nel canale uditivo, eviterei il termine umbo ignoto ai più confermano i dati sperimentali e teorici di letteratura. I metodi generalizzati, validati mediante infittimento della discretizzazione con metodo FEM standard, mostrano vantaggi in termini computazionali in quanto permettono di avere elevata accuratezza con discretizzazioni relativamente rade
Finite element formulations applied to outer ear modeling
No full textThe work described in this paper is part of a broader research activity on the development of a virtual ear. The present study focuses on the tympanic membrane and auditory canal modeling, which are important components in sound transmission. The standard finite element method (FEM) and an alternative method (the generalized FEM), suitable for modeling sound propagation at high frequencies, were applied. Two domains (fluid and structural) for the auditory canal and the tympanic membrane, respectively, were considered in order to evaluate the coupling of the different methods and to apply a fluid-structure interaction formulation. ANSYS® software was used for solving FEM analyses, while GFEM simulations were obtained by implementing the method in Wolfram Mathematica®. Simulation results include modal response, pressure distribution in the auditory canal and displacement distribution in the tympanic membrane. The identified modal frequencies of the auditory canal agree with published data reported in the literature. The validation of such method with standard FEM simulation at increasing mesh density shows that FEM is more suitable for simulations of the human ear in the audible frequency range, although the generalized formulation could be convenient if an ear model including the whole head or the ultrasound frequency range were investigated. © 2014 Journal of Mechanical Engineering
Biomechanics of the tympanic membrane
No full textThe tympanic membrane is a key component of the human auditory apparatus which is a complex biomechanical system, devoted to sound reception and perception. Over the past 30 years, various bioengineering approaches have been applied to the ear modeling and particularly to the middle part. The tympanic membrane, included in the middle ear, transfers sound waves into mechanical vibration from the ear canal into the middle ear. Changes in structure and mechanical properties of the tympanic membrane due to middle ear diseases or damages can deteriorate sound transmission. An accurate model of the tympanic membrane, which simulates the acoustic-mechanical transmission, could improve clinical surgical intervention.In this paper a detailed survey of the biomechanics and the modeling of the tympanic membrane focusing on the finite element method is conduced. Eight selected models are evaluated and compared deducing the main features and most design parameters from published models, mainly focusing on geometric, constraint and material aspects. Non-specified parameters are replaced with the most commonly employed values.Our simulation results (in terms of modal frequencies and umbo displacement), compared with published numerical and experimental results, show a good agreement even if some scattering appears to indicate the need of further investigation and experimental validation
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