An elemental approach to modelling the mechanics of the cochlea

Elliott, Stephen J.; Ni, Guangjian

doi:10.1016/j.heares.2017.10.013

Cited by 24 publications

(24 citation statements)

References 38 publications

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“…The properties of the passive cochlea can be reasonably well reproduced if one-dimensional fluid coupling is assumed, together with single-degree-of-freedom dynamics of the cochlear partition, with an exponential distribution of natural frequencies 13 . An entirely acoustic system can also be designed to reproduce the behaviour of the cochlea, consisting of discrete elements, provided that a sufficiently large number of elements is used.…”

Section: Resultsmentioning

confidence: 95%

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Cochlea-inspired design of an acoustic rainbow sensor with a smoothly varying frequency response

Karlos

Elliott

2020

Sci Rep

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A number of physical arrangements for acoustic rainbow sensors have been suggested, where the aim is to separate different frequency components into different physical locations along the sensor. Although such spatial discrimination has been achieved with several designs of sensor, the resulting frequency responses at a given position along the sensor are generally not smoothly varying. In contrast, the cochlea provides an interesting natural example of a rainbow sensor, which has an exponential frequency distribution and whose response does vary smoothly with frequency. The design of a rainbow sensor is presented that has a number of discrete resonators and an exponential frequency distribution. We discuss the conditions for a smoothly varying frequency response in such a sensor, as part of a broader design strategy. It is shown that the damping within the resonators determines the trade-off between the frequency resolution and the number of elements required to achieve a smooth response. The connection is explained between this design and that of an effective acoustic absorber. The finite number of hair cells means that the cochlea itself can be thought of as being composed of discrete units and the conditions derived above are compared with those that are observed in the cochlea.

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Section: Resultsmentioning

confidence: 95%

“…The audible spectrum for young people is around 10 octaves 25 , leading to about 300 elements per octave. In the passive cochlea, the local resonance quality factor is around 13 2.5, which, according to Eq. (8), gives a minimum requirement of only about 8 elements per octave.…”

Section: Discussionmentioning

confidence: 99%

Cochlea-inspired design of an acoustic rainbow sensor with a smoothly varying frequency response

Karlos

Elliott

2020

Sci Rep

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“…where ν is the kinematic viscosity, ρ is the fluid density, and t is time. Fluid viscosity has been considered [15][16][17][18][19] or neglected [20][21][22][23] per the purpose of studies. To our knowledge, no previous study regarding cochlear fluids analyzed the effect of advection (the second term of Eq.…”

Section: Methodsmentioning

confidence: 99%

Mechanically facilitated micro-fluid mixing in the organ of Corti

Shokrian

Knox

Kelley

et al. 2020

Sci Rep

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The cochlea is filled with two lymphatic fluids. Homeostasis of the cochlear fluids is essential for healthy hearing. The sensory epithelium called the organ of Corti separates the two fluids. Corti fluid space, extracellular fluid space within the organ of Corti, looks like a slender micro-tube. Substantial potassium ions are constantly released into the Corti fluid by sensory receptor cells. Excess potassium ions in the Corti fluid are resorbed by supporting cells to maintain fluid homeostasis. Through computational simulations, we investigated fluid mixing within the Corti fluid space. Two assumptions were made: first, there exists a longitudinal gradient of potassium ion concentration; second, outer hair cell motility causes organ of Corti deformations that alter the cross-sectional area of the Corti fluid space. We hypothesized that mechanical agitations can accelerate longitudinal mixing of Corti fluid. Corti fluid motion was determined by solving the Navier–Stokes equations incorporating nonlinear advection term. Advection–diffusion equation determined the mixing dynamics. Simulating traveling boundary waves, we found that advection and diffusion caused comparable mixing when the wave amplitude and speed were 25 nm and 7 m/s, respectively. Higher-amplitude and faster waves caused stronger advection. When physiological traveling waves corresponding to 70 dB sound pressure level at 9 kHz were simulated, advection speed was as large as 1 mm/s in the region basal to the peak responding location. Such physiological agitation accelerated longitudinal mixing by more than an order of magnitude, compared to pure diffusion. Our results suggest that fluid motion due to outer hair cell motility can help maintain longitudinal homeostasis of the Corti fluid.

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“…Of American adults over age 18, 15% report having some difficulty in hearing [4]. Factors such as age, noise trauma, infection, and ototoxic drugs can lead to damage of sensory auditory hair cells in the inner ear (cochlea), leading to hearing impairment [4][5][6]. Any perturbation of the sound pathway can lead to hearing impairment.…”

Section: Introductionmentioning

confidence: 99%

Biocompatibility of Bone Marrow-Derived Mesenchymal Stem Cells in the Rat Inner Ear following Trans-Tympanic Administration

Eshraghi

Ocak

Zhu

et al. 2020

JCM

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Recent advancements in stem cell therapy have led to an increased interest within the auditory community in exploring the potential of mesenchymal stem cells (MSCs) in the treatment of inner ear disorders. However, the biocompatibility of MSCs with the inner ear, especially when delivered non-surgically and in the immunocompetent cochlea, is not completely understood. In this study, we determined the effect of intratympanic administration of rodent bone marrow MSCs (BM-MSCs) on the inner ear in an immunocompetent rat model. The administration of MSCs did not lead to the generation of any oxidative stress in the rat inner ear. There was no significant production of proinflammatory cytokines, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-12, due to BM-MSCs administration into the rat cochlea. BM-MSCs do not activate caspase 3 pathway, which plays a central role in sensory cell damage. Additionally, transferase dUTP nick end labeling (TUNEL) staining determined that there was no significant cell death associated with the administration of BM-MSCs. The results of the present study suggest that trans-tympanic administration of BM-MSCs does not result in oxidative stress or inflammatory response in the immunocompetent rat cochlea.

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An elemental approach to modelling the mechanics of the cochlea

Cited by 24 publications

References 38 publications

Cochlea-inspired design of an acoustic rainbow sensor with a smoothly varying frequency response

Cochlea-inspired design of an acoustic rainbow sensor with a smoothly varying frequency response

Mechanically facilitated micro-fluid mixing in the organ of Corti

Biocompatibility of Bone Marrow-Derived Mesenchymal Stem Cells in the Rat Inner Ear following Trans-Tympanic Administration

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