1. AY-REU Project 7: Functional Model of a Cadaveric Human Middle Ear William Holden, Senior Chemical Engineering Margaret Welch, Pre-Junior Biomedical Engineering College of Engineering and Applied Science, University of Cincinnati; Cincinnati, Ohio Mentor: Dr. Vasile Nistor, CEAS-Biomedical Engineering Sponsored by the National Science Foundation Grant ID No.: DUE-0756921

2. Presentation Outline 1.Background 2.Experimental Objectives 3.Measurement and Analysis Methods 4.Results 5.Conclusions

3. Background Many ailments lead to middle ear damage A functional model is needed to better test prostheses and prepare surgeons Using MicroCT and rapid 3-D printing, models could be customized to patients 3-D Model of Incus bone created in previous senior design project

4. Experimental Objectives Long Term Goal: Create an accurate functional model of the human middle ear Our Project’s Goals: Develop measurement setup and techniques to evaluate model performance Determine repeatability of measurements Develop analysis methods from LDV measurements

5. Measurement Setup Tripod for mounting laser Middle Ear Model Driving piston Beam tracking Laser Doppler Vibrometer

6. Laser Doppler Vibrometry Laser sample beam directed at surface to be measured Vibrating surface reflects and Doppler shifts beam Doppler shift is measured to determine surface velocity

7. Measurement Methods Measure: Velocity of different parts of model: Malleus, Short Process, Stapes At different angles For different driving amplitudes For different driving frequencies Coleman, J. “Organs of Hearing." Biological Foundations of Language: Speaking and Hearing. (Apr. 4, 2013)

8. Analysis Methods Axis of motion Frequency spectrum of velocities Response linearity Measurement repeatability

9. Axis of Motion For stapes, motion was determined to be piston-like, in and out of the oval window Determining axis of motion of stapes can be point of comparison Axis of motion can be determined for different points Method could be extrapolated to three dimensions From: Chien, W., Rosowski, J. J., Ravicz, M. E., Rauch, S. D., Smullen, J., and Merchant, S. N. (2009). "Measurements of stapes velocity in live human ears." Hearing Research, 249(1-2), 54-61.

10. Axis of Motion V θ Sample Beam

11. Axis of Motion Measurements taken at different angles Beam path traced onto paper Angles between paths estimated

12. Axis of Motion Angle Average Peak Frequency (Hz) Stdev (Hz) Average Peak Velocity (um/sec) Stdev (um/sec) Estimated θ (deg) V T *Cos(β-θ) Difference divided by Standard Deviation 0degree499.470.061242790.01251 0.12 Angle1499.690.36270210520.12630 0.68 Angle2499.640.10372414142.13767 0.30 Angle3499.860.5259356-8.4619 0.48 1 2 3 True Axis Model Equation:

13. Axis of Motion Defined 0° Determined Axis Usual Assumed Measured

14. Frequency Spectrum of Velocities Several publications use this form of measurement Velocities are measured for interval of frequencies Velocity versus frequency plot is made

15. Frequency Spectrum of Velocities Stapes Head Malleus Driving Piston: Frequency Range: 10-90 Hz Amplitude: 3 Volts Measurement Points: Stapes & Malleus

16. Frequency Spectrum of Velocities

19. Response Linearity Previous work has shown a linear response of measured velocities for changing pressures We tested linearity of measured velocity for changing driving voltages

20. Response Linearity These measurements were made on the Malleus of the model.

21. Response Linearity These measurements were made on the Malleus of the model.

22. Measurement Repeatability Measurement repeatability was tested by taking multiple measurements Between measurements, the setup was reconstructed

23. Measurement Repeatability These measurements were made on the Malleus of the model.

24. Conclusions LDV measurement setup and techniques have been successfully demonstrated LDV measurement repeatability has been verified Analysis methods have been created that allow for model performance to be evaluated Analysis methods will allow for improvement of future models with increasing accuracy

25. Project #7 - Functional Model of a Cadaveric Human Middle Ear Long Term Goal: Create an accurate functional model of the human middle ear Our Project’s Goals: Develop measurement setup and techniques to evaluate model performance Determine repeatability of measurements Develop analysis methods from LDV measurements