Characterizing middle ear reflectance via pole-zero fitting

Robinson, Sarah

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https://hdl.handle.net/2142/44235 Copy

Description

Title

Characterizing middle ear reflectance via pole-zero fitting

Author(s)

Robinson, Sarah

Issue Date

2013-05-24T21:55:05Z

Director of Research (if dissertation) or Advisor (if thesis)

Allen, Jont B.

Department of Study

Electrical & Computer Eng

Discipline

Electrical & Computer Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• middle ear
• reflectance
• poles
• zeros
• bacterial biofilm

Abstract

This thesis characterizes middle ear complex acoustic reflectance (CAR) and impedance by fitting poles and zeros to real-ear measurements. The goal of this work is to establish a quantitative connection between pole-zero locations and the underlying physical properties of CAR data. Most previous studies have analyzed CAR magnitude; while the magnitude accounts for reflected power, it does not encode latency information. Thus, an analysis that studies the real and imaginary parts of the data together could be more powerful. This is accomplished by fitting poles and zeros to the complex data. CAR data compiled from various studies are examined using this method, including data from Voss and Allen [1994], Rosowski et al. [2012], Nakajima et al. [2012] and a new study of bacterial biofilm [Nguyen et al., 2013]. Recent measurements were taken using a middle ear acoustic power analyzer (MEPA) system (HearID, Mimosa Acoustics), which makes complex acoustic impedance and reflectance measurements in the ear canal over the 0.2 to 6.0 kHz frequency range. Pole-zero fits to measurements over this range are achieved with an average RMS relative error of less than 3% using 12 poles. Factoring the reflectance fit into its all-pass and minimum-phase components approximates the effect of the ear canal, allowing for comparison across measurements. It was found that individual CAR magnitude variations for normal middle ears in the 1 to 4 kHz range can be characterized by closely-placed pole-zero pairs in that frequency region. Additionally, the characteristics of the pole-zero fit, such as the locations of the poles and zeros in the s-plane, differ between normal and pathological middle ears. This thesis establishes a methodology for examining the physical and mathematical properties of CAR using a parametric model. Pole-zero modeling shows promise for concise parameterization of CAR data and for identification of middle ear pathologies. Results of a novel study of CAR in the presence of bacterial biofilm are also presented.

Graduation Semester

2013-05

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http://hdl.handle.net/2142/44235

Copyright and License Information

Copyright 2013 Sarah R. Robinson

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