FEA for Outer Ear Acoustic Analysis
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The purpose of this study is to evaluate the accuracy of hearing test equipment in testing new-born infants. Infants are born with a wide range of outer ear sizes and shapes. As a result the sound signals sent from the outside reach the ear drum at different amplitude levels. This makes the tests inconsistent. One way to remedy the problem is to quantify the extent of sound loss in the outer ear canal as an effective "impedance" and use it to adjust the signal level from the test device. |
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Detailed Ear Geometry from MRI Scan Data |
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To avoid invasive procedures on patients, a Finite Element Analysis (FEA) approach is adopted. Prior to simulating a detailed ear shape, an acoustic problem for a simplified rectangular duct with known analytic solution was simulated and validated. |
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Rectangular Duct Acoustic Validation Problem |
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Imaginary and Real Pressure Solution
(within 1% error for all points) |
Resolved Resonance Frequency Modes
(within 0.4% error up to mode 9) |
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Having validated our numerical model, we moved on to the simulation of the outer ear canal. At the canal entrance, we imposed single tone signals with specific amplitude and frequency levels typical of the hearing test process. The pressure and frequency responses on the ear drum were collected at each combination. |
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Real part of Pressure Solution |
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This data is finally utilized to estimate the outer ear canal acoustic impedance as a function of signal frequency. In addition, resonant frequencies characteristic of the ear canal shape and size were also compiled. At resonant frequencies, the outer ear canal imposes the least impedance to the |
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Resonant Frequency Modes |
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