Math 596a (September 2008) - Auditory Periphery
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Overview
Dates/Times: Tuesday afternoons at 3:30 PM throughout September 2008 (9/9/08, 9/16, 9/23 & 9/30)
Location: Keating 103
The purpose of this section is to focus on a unique property of the auditory periphery: the emission of acoustic energy from the inner ear. In addition to being a mechano-electro transducer (converting incoming acoustical energy in electrical signals that trigger synapsed auditory nerve fibers), the ear also generates and subsequently emits energy spontaneously (in the absence of any external stimuli). These spontaneous otoacoutic emissions (SOAEs) typically only occur in healthy ears and are thought to be a by-product of amplification mechanisms present in the inner ear. Indeed, SOAEs are the most striking evidence for the notion of an 'active ear'. Our basic approach will be to examine basic SOAE properties and various classes of mathematical models for their generation.
The structure of this section will be a bit different than the others. There will be a series of papers that the students will read and subsequently present that will form the backbone of the section and the subsequent discussions. The first week a background lecture on the auditory periphery will be given to get the student's acquainted with the flavor of the problem. Groups/papers will be assigned at this point in time. The next two weeks will be comprised entirely of student presentations.
On the final week, we will have a group discussion based upon questions formulated by each group with respect to the other student's presentations (see below). The goal is to try to come to some consensus in terms of understanding the mechanisms underlying the generation of spontaneous otoacoustic emissions. Furthermore, we would like to discuss what (if anything) we can conclude about the notion of an 'active cochlea'. Lastly, each group will give a brief presentation on their analysis of actual SOAE data (see below).
Overview slides from 9/9 lecture can be found here
Student-submitted discussion questions can be found here
Questions? Contact cbergevin [AT] math.arizona.edu
Schedule
- Week 1 (9/9) - Background lecture (by C. Bergevin) on basic auditory physiology, OAEs and the idea of an 'active ear'. Groups will be assigned (each comprised of at least two students).
- Week 2 (9/16) - Groups 1-3 will each give a 20-25 min. presentation on their respective papers. All non-presenting groups will be expected to do two things:
a. submit a one page critique of the presenting group with regard to content, clarity (e.g. how well do they understand the material?) and style; these critiques will subsequently be given to the respective group in order to provide them with direct and critical feedback
b. formulate two 'critical questions' based upon the presentation's content that will be used as discussion points for Week 4
NOTE: these two assignments will be due before the following week's session (and can thus be submitted electronically)
- Week 3 (9/23) - Groups 4-6 will each give a 20-25 min. presentation on their respective papers. Similarly, all non-presenting groups will be expected to do as outlined for the 9/16 case.
- Week 4 (9/30) - Group discussion focused on the 'critical questions' each group composed (w/ respect to the other group's presentations). Also, each group will be expected to present their results based upon heir actual SOAE measurements and subsequent data analysis (described further below).
Papers
Each group is assigned a given paper to present, but each student is expected to read all the papers (i.e. at least look over). For the presentations, each group can take whatever approach they seem fit. Basically, we would expect some description of the underlying biology, how mathematics were introduced to get some traction on the problem, the main take-home message the authors wanted to convey and whether or not you agree with it. A computer/projector will be available if students choose to use such.
Week 2 (9/16)
- Group 1 (Sanket) - The first paper (Zurek, JASA 1981) describes early SOAE measurements.
- Group 2 (Mark) - This paper (Bialek and Wit, Phys. Rev. 1984) posits a simple model for SOAE generation based upon 'quantum-limited oscillations'.
- Group 3 (Christoph) - This paper (van Dijk and Wit, JASA 1990) examines some statistical properties of SOAEs and describes various incarnations of a second-order oscillator model for SOAE generation.
Week 3 (9/23)
- Group 4 David & Joe) - This paper (Talmadge et al., JASA 1991) presents a SOAE model based upon a self-sustained oscillator that has various forms of nonlinearity incorporated into it.
- Group 5 (Suzzanne & Rosalyn) - The model in this paper (Shera, JASA 2003) takes a different slant and considers emissions as arising from the ear as a whole.
- Group 6 (Ben) - This paper (Vilfan and Duke, Biophys. J. 2008) considers SOAEs from lizard ears as arising from a series of coupled oscillators.
Lab
At some point between Weeks 2 and 4 (i.e. 9/16-9/30), students will have an opportunity to measure SOAE time waveforms from their own ears. The actual data acquisition will take in an acoustic booth in the Speech and Hearing building. The data can than be transferred and analyzed in whatever fashion the groups seem fit. Times can be scheduled at each group's convenience. This data analysis of will form part of the discussion on Week 4 (9/30).