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Research Papers: Flows in Complex Systems

Pressure Distribution in a Simplified Human Ear Model for High Intensity Sound Transmission

[+] Author and Article Information
Takumi Hawa

School of Aerospace
and Mechanical Engineering,
The University of Oklahoma,
865 Asp Avenue,
Felgar Hall Room 218,
Norman, OK 73019
e-mail: hawa@ou.edu

Rong Z. Gan

School of Aerospace
and Mechanical Engineering
and OU Bioengineering Center,
The University of Oklahoma,
865 Asp Avenue,
Felgar Hall Room 218,
Norman, OK 73019
e-mail: rgan@ou.edu

lCorresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received July 30, 2013; final manuscript received February 27, 2014; published online September 4, 2014. Assoc. Editor: John Abraham.

J. Fluids Eng 136(11), 111108 (Sep 04, 2014) (7 pages) Paper No: FE-13-1462; doi: 10.1115/1.4027141 History: Received July 30, 2013; Revised February 27, 2014

High intensity noise/impulse transmission through a bench model consisting of the simplified ear canal, eardrum, and middle ear cavity was investigated using the CFX/ANSYS software package with fluid-structure interactions. The nondimensional fluid-structure interaction parameter q and the dimensionless impulse were used to describe the interactions between the high intensity pressure impulse and eardrum or tympanic membrane (TM). We found that the pressure impulse was transmitted through the straight ear canal to the TM, and the reflected overpressure at the TM became slightly higher than double the incident pressure due to the dynamic pressure (shocks) effect. Deformation of the TM transmits the incident pressure impulse to the middle ear cavity. The pressure peak in the middle ear cavity is lower than the incident pressure. This pressure reduction through the TM was also observed in our experiments that have dimensions similar to the simulation bench model. We also found that the increase of the pressure ratio as a function of the incident pressure is slightly larger than the linear growth rate. The growth rate of the pressure ratio in this preliminary study suggests that the pressure increase in the middle ear cavity may become sufficiently high to induce auditory damage and injury depending on the intensity of the incident sound noise.

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References

Figures

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Fig. 1

Geometry of the model

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Fig. 2

A typical example of variation of the blast overpressure with time at the entrance of the ear canal model

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Fig. 3

Taylor's plot (momentum ratio, I/I0 versus q) for considering fluid-structure interaction

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Fig. 4

Reflected pressure wave magnitudes against a solid wall with various inlet or incident pressures

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Fig. 5

Pressure ratio dependence of the number of nodes in the flow field

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Fig. 6

TM deflection dependence of the number of nodes of the TM structure

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Fig. 7

(a) Illustration of the design of the bench model and (b) picture of the bench model with inserted pressure sensors placed inside of the blast or high intensity sound test chamber

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Fig. 8

(a) Typical waveform of p0 (pressure amplitude-time curve) measured in bench model and (b) waveform of p2 measured in bench model

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Fig. 9

A simulation of pressure propagation through the ear canal, TM, and cavity at six different times, t = 0.02, 0.04, 0.06, 0.08, 0.10, and 0.12 ms when t0 = 90 μs, ρs = 36 kg/m3, and EY = 6 × 105N/m2

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Fig. 10

Pressure ratio p0/p2 dependence of input pressure p0

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Fig. 11

Pressure ratio p0/p2 dependence on q

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