The human otitis media with effusion: a numerical-based study B. Areias a , M. P. L. Parente a,b , C. Santos b , F. Gentil c,d and R. M. Natal Jorge a,b a INEGI, Institute of Science and Innovation in Mechanical and Industrial Engineering, Porto, Portugal; b FEUP, Faculty of Engineering, University of Porto, Porto, Portugal; c ESS, Escola Superior de Saúde, P. Porto, Porto, Portugal; d Clínica ORL – Dr. Eurico de Almeida, Porto, Portugal ABSTRACT Otitis media is a group of inflammatory diseases of the middle ear. Acute otitis media and otitis media with effusion (OME) are its two main types of manifestation. Otitis media is common in children and can result in structural alterations in the middle ear which will lead to hearing losses. This work studies the effects of an OME on the sound transmission from the external auditory meatus to the inner ear. The finite element method was applied on the present biomechanical study. The numerical model used in this work was built based on the geometrical information obtained from The visible ear project. The present work explains the mechanisms by which the presence of fluid in the middle ear affects hearing by calculating the magnitude, phase and reduction of the normalized umbo velocity and also the magnitude and phase of the normalized stapes velocity. A sound pressure level of 90 dB SPL was applied at the tympanic membrane. The harmonic analysis was performed with the auditory frequency varying from 100 Hz to 10 kHz. A decrease in the response of the normalized umbo and stapes velocity as the tympanic cavity was filled with fluid was obtained. The decrease was more accentuated at the umbo. KEYWORDS Otitis media; middle ear; tympanic cavity; biomechanics 1. Introduction Otitis media is a common disease characterized by the inflammation of the middle ear mucosal, with or without an effusion (Swarts et al. 2014). Often begins when an infection that causes sore throats, colds or other respi- ratory problems which then spreads to the middle ear, through the Eustachian tube. Otitis media with effusion (OME) is defined as the presence of fluid in the middle ear without signs or symptoms of acute ear infection. It generally occurs spontaneously, due to a poor Eusta- chian tube function or as an inflammatory response, following an acute otitis media (American Academy of Family Physicians 2004). The Eustachian tube has been described with three main functions: protection, pressure regulation and clearance (Douglas Swarts & Bluestone 2003). This tube is normally closed and can be opened by the contractions of the tensor veli palatini muscle during swallowing or passively opened by increasing the middle ear or nasopharyngeal pressure to supra-ambient levels (Doyle et al. 2013; Swarts et al. 2014). Experiments in monkeys and other animal species demonstrated that an inability to open the Eustachian tube causes the suc- cessive development of negative middle ear pressures, mucosal inflammation and effusion accumulation in the normally air-filled tympanic cavity (TC) (Doyle 1984). Otitis media is the primary cause of hearing losses in the population and is associated with other complications such as balance disturbances and speech and language development delays in children (Doyle et al. 2013). In infants, the Eustachian tube is shorter, wider and more horizontal than in adults, so the protective function of the tube may be lower in this age group (Daniel et al. 1988). The fluid present in the middle ear can be serous, mucoid or glue-like and the TC may be partly or completely filled with fluid. Fluid in the middle ear has been associated with a conductive hearing loss of 25 to 30 dB (Ravicz et al. 2004). The frequent presence of fluid in the TC results in a decreased mobility of the tympanic membrane and serves as a barrier to sound conduction. Approximately, 90% of children report episodes of OME at some time before the school age (American Academy of Family Physicians 2004; Valente et al. 2010; Atkinson et al. 2015). There are several experimental studies about otitis media in chil- dren. Numerical studies are important to understand the alterations caused by this disease and thus contribute to the development of more effective treatment techniques. The study reported here intends to show the influence of OME in the normal functioning of the human ear. A 3D model of the human ear was developed and the finite element method was applied to obtain the responses in the umbo and in the stapes footplate. A comparison of the responses with previously published data in the literature