title: A single-ossicle ear: Acoustic response and mechanical properties measured in duck.
abstract: To date, the single-ossicle avian middle ear (ME) is poorly understood, despite its striking resemblance to the design of many currently used ossicular replacement prostheses. This study aims to improve comprehension of this system. The acoustic response and the mechanical properties of the mallard middle ear were studied by means of optical interferometry experiments and finite element (FE) simulations. A finite element model was constructed based on μCT data and validated using the experimental results. Stroboscopic holography was used to measure the full-field displacement of the tympanic membrane (TM) under acoustic stimulation, and the transfer function was obtained with laser Doppler vibrometry. A sensitivity analysis concluded that the most influential parameters for ME mechanics are the elasticity of the TM, the extracolumella (the cartilaginous part of the columella) and the annular ligament of the columellar footplate. Estimates for the Young's modulus of the TM were obtained by iteratively updating the FE model to match experimental data. A considerable inter-individual variability was found for the TM's elasticity. Comparison of the experimental results and the optimized FE model shows that, similar to the human middle ear, damping needs to be present in the TM to describe the specific spatial and frequency dependent vibrations of the TM. In summary, our results indicate which mechanical parameters are essential to the good functioning of the avian ME and provide a first estimation of their values.
authors.affiliation: Laboratory of Biophysics and Biomedical Physics, University of Antwerp, Groenenborgerlaan 121, 2020 Antwerp, Belgium. Electronic address: pieter.muyshondt@uantwerpen.be.
authors.forename: Pieter G G
authors.initials: PGG
authors.lastname: Muyshondt
authors.affiliation: Laboratory of Biophysics and Biomedical Physics, University of Antwerp, Groenenborgerlaan 121, 2020 Antwerp, Belgium.
authors.forename: Joris A M
authors.initials: JAM
authors.lastname: Soons
authors.affiliation: Laboratory of Biophysics and Biomedical Physics, University of Antwerp, Groenenborgerlaan 121, 2020 Antwerp, Belgium.
authors.forename: Daniël
authors.initials: D
authors.lastname: De Greef
authors.affiliation: Laboratory of Biophysics and Biomedical Physics, University of Antwerp, Groenenborgerlaan 121, 2020 Antwerp, Belgium; Department of Mechanical Engineering, Free University of Brussels, Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Felipe
authors.initials: F
authors.lastname: Pires
authors.affiliation: Functional Morphology, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Aerts
authors.affiliation: Laboratory of Biophysics and Biomedical Physics, University of Antwerp, Groenenborgerlaan 121, 2020 Antwerp, Belgium.
authors.forename: Joris J J
authors.initials: JJJ
authors.lastname: Dirckx
mesh_terms: D000161:Acoustic Stimulation; D000162:Acoustics; D000818:Animals; D004372:Ducks / Q000502:physiology*; D004429:Ear Ossicles / Q000502:physiology*; D004432:Ear, Middle / Q000502:physiology*; D055119:Elastic Modulus; D005260:Female; D020342:Finite Element Analysis; D006696:Holography; D006801:Humans; D007834:Lasers; D008297:Male; D008953:Models, Anatomic; D009998:Ossicular Prosthesis; D013199:Stapes / Q000502:physiology; D014432:Tympanic Membrane / Q000502:physiology*; D014732:Vibration
keywords: Avian middle ear; Finite element modeling; Laser vibrometry; Model optimization; Stroboscopic holography