scholarly journals A simplified analytical model of sound propagation in the human ear

2019 ◽  
Author(s):  
Wiktor L. Gambin
Keyword(s):  
Elastic Wave ◽  
Sound Wave ◽  
Sound Source ◽  
Sound Propagation ◽  
Basilar Membrane ◽  
Round Window ◽  
Round Window Membrane ◽  
Ear Canal ◽  
Stapes Footplate ◽  
Human Ear

AbstractA simple mechanical model of sound propagation in the human ear from the entrance to the ear canal up to the round window membrane is outlined. The model shows the outer, middle and inner ear as two waveguides connected by a lever mechanism. The case when a sound wave from a sound source at a given frequency and intensity goes into the ear is considered. The sound as a plane elastic wave in the air of the ear canal is partially reflected from the eardrum and after relocation by a lever of the ossicles; it runs as a plane elastic wave in the cochlea fluid to be finally damped at the round window membrane. The basilar membrane excited by the running sound wave in the cochlea is taken as a chain of separate fibers. The power of the sound reaching the ear is compared with the power of the sound carriers in the ear. As a result, simple rules for the amplitude of the stapes footplate as well as for the amplitude and pressure of the forced acoustic wave in the cochlea are obtained. The formulas for the amplitudes of the membrane of the round window and the basilar membrane are also shown. The results of calculations based on these rules were compared with the measurements made on temporal bone specimens. The tests were done for the level of the sound source intensity of 90 dB and a set of frequencies from the range of 400-10,000 Hz. The amplitudes of the stapes-footplate and the round window membrane were measured. A mean difference, between the calculated and the measured values, for the stapes-footplate reached 31%, and for the round window membrane, it was 21%. A ratio of the basilar membrane velocity to the stapes footplate velocity as a function of the frequencies was shown. The obtained graph was close to that got by others as a result of the measurements.

3D Finite Element Modeling of Blast Wave Transmission From the External Ear to a Spiral Cochlea

2021 ◽  
Author(s):  
Marcus Brown ◽  
John Bradshaw ◽  
Rong Z. Gan
Keyword(s):  
Finite Element ◽  
Middle Ear ◽  
Basilar Membrane ◽  
Transverse Motion ◽  
Fe Model ◽  
Ear Canal ◽  
Blast Overpressure ◽  
Stapes Footplate ◽  
Human Ear ◽  
Temporal Bones

Abstract Blast-induced injuries affect the health of veterans, in which the auditory system is often damaged, and blast-induced auditory damage to the cochlea is difficult to quantify. A recent study modeled blast overpressure (BOP) transmission throughout the ear utilizing a straight, two-chambered cochlea, but the spiral cochlea's response to blast exposure has yet to be investigated. In this study, we utilized a human ear finite element (FE) model with a spiraled, two-chambered cochlea to simulate the response of the anatomical structural cochlea to BOP exposure. The FE model included an ear canal, middle ear, and two and half turns of two-chambered cochlea and simulated a BOP from the ear canal entrance to the spiral cochlea in a transient analysis utilizing fluid-structure interfaces. The model's middle ear was validated with experimental pressure measurements from the outer and middle ear of human temporal bones. The results showed high stapes footplate displacements up to 28.5µm resulting in high intracochlear pressures and basilar membrane (BM) displacements up to 43.2µm from a BOP input of 30.7kPa. The cochlea's spiral shape caused asymmetric pressure distributions as high as 4kPa across the cochlea's width and higher BM transverse motion than that observed in a similar straight cochlea model. The developed spiral cochlea model provides an advancement from the straight cochlea model to increase the understanding of cochlear mechanics during blast and progresses towards a model able to predict potential hearing loss after blast.

scholarly journals Sound transmission by chamber prosthesis of the middle ear

2020 ◽  
Author(s):  
Wiktor L. Gambin
Keyword(s):  
Middle Ear ◽  
Sound Wave ◽  
Round Window ◽  
Sound Transmission ◽  
Sound Frequency ◽  
Round Window Membrane ◽  
Stapes Footplate ◽  
Flow Through ◽  
Temporal Bones ◽  
Vibrating Plate

AbstractTests done on specimens cut from the temporal bones show, that the stapedotomy can be more effective, if instead of the piston prosthesis, the ear chamber prosthesis is used. In that case, the vibrations of the eardrum are transferred to a plate with attachment sticked to the incus. The plate is suspended on a membrane stretched on the base of conical chamber which is filled with a fluid and placed in the middle ear cave. The sound wave caused by a vibrating plate, is focused at the chamber outlet placed in a small hole drilled in the stapes footplate. As in the case of the piston prosthesis behavior of the round window membrane differs from that observed in the normal ear. The flow through a narrow outlet of the conical chamber makes a more deflection of the central part of the round window membrane. The properties of the prosthesis elements are close to those of the removed parts of the middle ear. In spite of this, one can observe a different sound transmission inside the ear. When the sound is higher than 1000 Hz, the vibration amplitude of the plate is 5-10 dB higher than that for the stapes footplate in the healthy ear. However, when the sound is lower than 1000 Hz, this amplitude is lower than that for the stapes footplate. To explain it, a simplified model of the sound propagation in the ear given in the prior work is used. To get a better agreement with the test results, the model takes into account a damping of the sound wave by the round window membrane. Next, the model is adapted to the ear with chamber prosthesis. The factors that may have an effect on the behavior of the sound wave are examined. The first is shortening of the incus. It increases the leverage of the ossicles and the force acting on the prosthesis plate compared to that in the normal ear. Next factor is a reduction of the mass of the vibrating plate what makes a growth of its resonance frequency. This slightly reduces the amplitude of the plate for the low sounds and increases it for the medium and the higher sounds. At end, the lack of the influence of the flow through the conical chamber on the sound wave energy is shown. The assumed model gives the rules for amplitudes of the chamber plate as functions of the sound frequency. Their values for the sound frequency from 400 Hz to 8000 Hz and its graphs are shown and compared with those for the stapes footplate in the normal ear. One can see that if the sound frequency is higher than 1000 Hz, then the chamber prosthesis makes higher amplitudes of the sound wave than the normal ear. To explain their drop for frequencies lower than 1000 Hz, needs more tests in this range.

FINITE ELEMENT ANALYSIS OF THE EFFECT OF ACTUATOR COUPLING CONDITIONS ON ROUND WINDOW STIMULATION

2015 ◽  
Vol 15 (04) ◽  
pp. 1550048 ◽  
Author(s):  
JIABIN TIAN ◽  
XINSHENG HUANG ◽  
ZHUSHI RAO ◽  
NA TA ◽  
LIFU XU
Keyword(s):  
Finite Element ◽  
Middle Ear ◽  
Round Window ◽  
Round Window Membrane ◽  
Fe Model ◽  
Ear Canal ◽  
Sound Stimulation ◽  
Fe Method ◽  
Coupling Conditions ◽  
Intracochlear Pressure

The finite element (FE) method was used to analyze the effect of coupling conditions between the actuator and the round window membrane (RWM) on the performance of round window (RW) stimulation. A FE model of the human ear consisting of the external ear canal, middle ear and cochlea was firstly developed, and then validation of this model was accomplished through comparison between analytical results and experimental data in the literature. Intracochlear pressure were derived from the model under normal forward sound stimulation and reverse RW stimulation. The equivalent sound pressure of RW stimulation was then calculated via comparing the differential intracochlear pressure produced by the actuator and normal ear canal sound stimulus. The actuator was simulated as a floating mass and placed onto the middle ear cavity side of RWM. Two aspects about the actuator coupling conditions were considered in this study: (1) the cross-section area of the actuator relative to the RWM; (2) the coupling layer between the actuator and the RWM. The results show that smaller actuator size can improve the implant performance of RW stimulation, and size requirements of the actuator can also be reduced by introducing a coupling layer between the actuator and RWM, which will benefit the manufacture of the actuator.

Round window reflex and oval window fistulae

1989 ◽  
Vol 103 (6) ◽  
pp. 562-565 ◽  
Author(s):  
D. S. Grewal
Keyword(s):  
Round Window ◽  
Oval Window ◽  
Round Window Membrane ◽  
Diagnostic Sign ◽  
Stapes Footplate ◽  
Ligament Disruption

AbstractThe round window reflex is normally absent in stapedial fixation. In this study, six cases of oval window fistula are described in which the round window reflex was absent. This is probably because there is insufficient pressure transmitted to the round window membrane through the perilymph because of leakage from the oval window. This is considered as an important diagnostic sign of oval window/stapes footplate ligament disruption.

scholarly journals The Influence of Piezoelectric Transducer Stimulating Sites on the Performance of Implantable Middle Ear Hearing Devices: A Numerical Analysis

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 782 ◽  
Author(s):  
Liu ◽  
Zhao ◽  
Yang ◽  
Rao
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Middle Ear ◽  
Hearing Aids ◽  
Piezoelectric Transducer ◽  
Basilar Membrane ◽  
Round Window ◽  
Element Model ◽  
Round Window Membrane ◽  
Hearing Devices

To overcome the inherent deficiencies of hearing aids, implantable middle ear hearing devices (IMEHDs) have emerged as a new treatment for hearing loss. However, clinical results show that the IMEHD performance varies with its transducer’s stimulating site. To numerically analyze the influence of the piezoelectric transducer’s stimulating sites on its hearing compensation performance, we constructed a human ear finite element model and confirmed its validity. Based on this finite element model, the displacement stimulation, which simulates the piezoelectric transducer’s stimulation, was applied to the umbo, the incus long process, the incus body, the stapes, and the round window membrane, respectively. Then, the stimulating site’s effect of the piezoelectric transducer was analyzed by comparing the corresponding displacements of the basilar membrane. Besides, the stimulating site’s sensitivity to the direction of excitation was also studied. The result of the finite element analysis shows that stimulating the incus body is least efficient for the piezoelectric transducer. Meanwhile, stimulating the round window membrane or the stapes generates a higher basilar membrane displacement than stimulating the eardrum or the incus long process. However, the performance of these two ideal sites’ stimulation is sensitive to the changes in the excitation’s direction. Thus, the round window membrane and the stapes is the ideal stimulating sites for the piezoelectric transducer regarding the driving efficiency. The direction of the excitation should be guaranteed for these ideal sites.

Research on coupling effects of actuator and round window membrane on reverse stimulation of human cochlea

2021 ◽  
pp. 095441192098796
Author(s):  
Lin Xue ◽  
Houguang Liu ◽  
Jianhua Yang ◽  
Songyong Liu ◽  
Yu Zhao ◽  
...  
Keyword(s):  
Middle Ear ◽  
Coupling Effect ◽  
Round Window ◽  
Ossicular Chain ◽  
Round Window Membrane ◽  
Coupling Impedance ◽  
Coupling Condition ◽  
Impedance Model ◽  
Middle Ear Implant ◽  
Human Ear

An active actuator of a middle-ear implant coupled to the round window membrane (RWM), which transmits vibration to the cochlea, has been used to compensate for hearing loss in patients. However, various factors affect the coupling condition between the actuator and the RWM, resulting in coupling leakage. In this study, a coupling impedance model of the human ear and the actuator was used to investigate the effect of inefficient coupling during reverse stimulation. First, the three-port circuit network model of the actuator was coupled with the acoustic impedance model of human ear reverse sound transmission. Meanwhile, the inefficient coupling impedance was estimated. Then, the effect of the actuator’s coupling on reverse stimulation was studied by comparing the reverse pressure transfer function. Furthermore, the inefficient coupling’s influence in the ear with middle-ear disorder was also investigated by simulating two typical forms of middle-ear disorder: otosclerosis and ossicular chain disarticulation. The results show that the change of the inefficient coupling impedance plays a significant role during reverse stimulation. Inefficient coupling of the actuator and the RWM deteriorates the cochlear response of reverse stimulation over the entire frequency range. Additionally, the coupling effect of the actuator does not change the influence tendency of middle-ear disorder on reverse stimulation’s performance, but changes the response amplitude of the reverse stimulation.

scholarly journals Why the middle ear piston prosthesis is not effective enough and how to change it?

2020 ◽  
Author(s):  
Wiktor L. Gambin
Keyword(s):  
Middle Ear ◽  
Sound Propagation ◽  
Basilar Membrane ◽  
Spherical Wave ◽  
Secondary Wave ◽  
Guide Tube ◽  
Primary Wave ◽  
Sound Perception ◽  
Cochlear Amplification ◽  
Stapes Footplate

AbstractPiston prostheses of the middle ear do not ensure sufficient audibility of high and low sounds. To find out the reason, the amplitudes of the vibrations for the stapes footplate and the piston end were compared. It was seen that for a given force that oscillates with a low frequency, the amplitude of the piston end was higher than the amplitude of the stapes footplate. This means that the stiffness of the tissue sealing up the piston in the footplate hole is lower than the stiffness of the stapes plate suspension. It was shown that as a result, for the case of the higher frequencies, the amplitude of the piston vibrations drops several times. Next, it was compared a sound propagation in the healthy ear with that in the ear after the stapedotomy. To do it, a previously prepared model of sound propagation in the ear was used. The model is simplified, but it gives all parameters of the sound wave in the cochlear fluid. According to it, a motion of the stapes footplate forms a plane wave, while the piston motion initially gives a wave similar to the spherical one. A part of the spherical wave with the front directed towards the apex forms the primary wave running in the cochlea. However, the rest of this wave has the front directed towards the stapes footplate. This wave part, after a reflection from the stapes footplate, creates a secondary wave that follows the primary wave. A splitting of the wavefront around the edge of the piston end is a source of disruptions in the sound perception. The shift of the secondary wave reduces the power of the primary wave; it disturbs the waving of the basilar membrane and may cause extra noise. To justify it, a graph of the level of the cochlear amplification for the ear with the piston prosthesis was shown. The result compared with a simulation for the healthy ear gave the values 5 dB lower. To remove these drawbacks, it was proposed to place the piston end, not inside the cochlea, but in a guide in the form of a tube ended with a funnel fixed in the hole made in the stapes footplate. The piston was suspended in a guide tube on an O-ring formed of silicone gel. It was shown that when the piston is in the guide, the level of cochlear amplification was the same as that in the healthy ear. Some design details of the new piston guide are given. It enables us to make the new piston prosthesis easily and put it into practice.

scholarly journals The Effects of Round Window Membrane Injury and the Use of a Model Electrode Application on Hearing in Rats

2021 ◽  
pp. 014556132199018
Author(s):  
Murat Koc ◽  
Abdullah Dalgic ◽  
Mehmet Ziya Ozuer
Keyword(s):  
Hearing Loss ◽  
Cochlear Implant ◽  
Round Window ◽  
Mechanical Trauma ◽  
Round Window Membrane ◽  
Albino Rats ◽  
Topical Steroids ◽  
Distortion Product ◽  
Significant Difference ◽  
Group 3

Objective: To investigate the effects of the mechanical trauma to the round window, a model electrode inserted into the scala tympani on the cochlear reserve, and the efficacy of topical steroids in preventing hearing loss. Materials and Methods: 21 male Wistar Albino rats were equally categorized into three groups. In all groups an initial mechanical injury to round window was created. Only subsequent dexamethasone injection was administrated into the cochlea in the subjects of group 2 while a multichannel cochlear implant guide inserted into the cochlea prior to dexamethasone administration for group 3. Distortion product otoacoustic emissions (DPOAEs) were obtained prior to and immediately after the surgical injury, eventually on postoperative seventh day (d 7). Mean signal/noise ratios (S/Ns) obtained at 2000, 3000, and 4000 Hz were calculated. Data sets were compared with non-parametric statistical tests. Results: The early intraoperative mean S/Ns were significantly less than preoperative measurements for group 1 and 2; however, preoperative and postoperative d 7 average S/Ns did not differ. There was statistically significant difference between preoperative, intraoperative and postoperative d 7 average S/Ns for group 3. Conclusion: We observed that hearing was restored approximately to the preoperative levels following early postoperative repair. However, an electrode insertion into the cochlea via round window subsequent to mechanical trauma seems to cause a progressive hearing loss. Therefore, a special care must be taken to avoid the injury to the round window membrane in the course of the placement of a cochlear implant electrode and surgery for the chronic otitis media.

scholarly journals Cochlear Implantation Following Explorative Tympanotomy in Patients With Sudden Sensorineural Hearing Loss: Surgical Features and Audiological Outcomes

2021 ◽  
pp. 014556132110091
Author(s):  
Robin Rupp ◽  
Joachim Hornung ◽  
Matthias Balk ◽  
Matti Sievert ◽  
Sarina Müller ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Connective Tissue ◽  
Sensorineural Hearing Loss ◽  
Cochlear Implantation ◽  
Round Window ◽  
Sudden Sensorineural Hearing Loss ◽  
Sensorineural Hearing ◽  
Round Window Membrane ◽  
Hearing Results ◽  
Round Window Niche

Objective: To investigate the anatomical status of the round window niche and hearing outcome of cochlear implantation (CI) after explorative tympanotomy (ExT) with sealing of the round window membrane in patients with sudden sensorineural hearing loss at a tertiary referral medical center. Methods: Between January 1, 2007, and July 30, 2020, 1602 patients underwent CI at our department. Out of these, all patients previously treated by ExT with sealing of the round window membrane because of unilateral sudden hearing loss were included in the study. A retrospective chart review was conducted concerning method of round window membrane sealing, intraoperative findings during CI, postoperative imaging, and hearing results. Results: Twenty one patients (9 females; 8 right ears; 54.3 years [± 12.9 years]) underwent ExT with sealing of the round window membrane with subsequent CI after 26.6 months (± 32.9 mo) on average. During CI, in 76% of cases (n = 16), the round window niche was blocked by connective tissue due to the previous intervention but could be removed completely in all cases. The connective tissue itself and its removal had no detrimental effects on the round window membrane. Postoperative computed tomography scan showed no electrode dislocation. Mean postoperative word recognition score after 3 months was 57.4% (± 17.2%) and improved significantly to 73.1% (± 16.4%, P = .005) after 2 years. Conclusion: Performing CI after preceding ExT, connective tissue has to be expected blocking the round window niche. Remaining tissue can be removed safely and does not alter the round window membrane allowing for a proper electrode insertion. Short- and long-term hearing results are satisfactory. Consequently, ExT with sealing of the round window membrane in patients with sudden sensorineural hearing loss does not impede subsequent CI that can still be performed safely.

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