Realizing the potential of otoacoustic emissions (OAEs) as noninvasive probes of cochlear function requires understanding the physical and physiological mechanisms that generate and shape these sounds. To address important unresolved issues of cochlear mechanics while improving our understanding of OAE generation, we propose three aims involving innovative theoretical modeling rigorously tested by experimental measurements.
The first Aim studies the action of ?suppressor? tones on OAE generation by testing the hypothesis that suppressors can both reduce the strength of existing OAE sources and create new sources of wave reflection within the cochlea. We determine whether suppressors can accurately map out the distribution of OAE generators in models where the distribution is known in advance and test whether eliminating sources created by the suppressor can improve the measurement of cochlear frequency selectivity using OAE suppression tuning curves.
The second Aim studies the nature of the micromechanical irregularity believed necessary for the generation of reflection-source OAEs. We test whether efferent-induced changes in OAEs can be explained by the hypothesis that activation of medial olivocochlear (MOC) efferents alters the spatial pattern of irregularity. Using both measurements and models, we also explore the hypothesized but previously unrecognized role of irregularity on the generation of distortion-source OAEs and its modulation by contralateral acoustic stimulation.
The third Aim explores the micromechanics of cochlear wave amplification and its consequences for OAE generation. Modeling work studies OAE generation in models incorporating forms of spatial feed-forward/backward amplification suggested by the oblique geometry of the outer hair cells. We also combine state-of-the-art measurements of organ of Corti vibration using optical coherence tomography (OCT) with theoretical inverse methods to study how the assumed coupling between the modes affects the generation and propagation of OAEs. Completion of these Aims will significantly enhance our understanding of OAE generation and its relationship to cochlear mechanics.
The Aims are also directly relevant to improving the power of OAE-based diagnostics and other technological applications?such as hearing aids and preprocessors for speech-recognition devices?that benefit from knowledge of cochlear amplification, nonlinearity, and signal processing.
Our experiments and models address the mechanisms by which healthy ears generate sound. Sounds from the ear, known as otoacoustic emissions (OAEs), are widely used for noninvasive tests of hearing function. By improving our understanding of how OAEs are produced within the cochlea, and how they can be used to probe aspects of cochlear function important for human communication, the proposed work will enhance the power of clinical hearing tests and help improve the design of auditory prosthetic devices.
| Sumner, Christian J; Wells, Toby T; Bergevin, Christopher et al. (2018) Mammalian behavior and physiology converge to confirm sharper cochlear tuning in humans. Proc Natl Acad Sci U S A 115:11322-11326 |
| Gruters, Kurtis G; Murphy, David L K; Jenson, Cole D et al. (2018) The eardrums move when the eyes move: A multisensory effect on the mechanics of hearing. Proc Natl Acad Sci U S A 115:E1309-E1318 |
| Abdala, Carolina; Guardia, Yeini C; Shera, Christopher A (2018) Swept-tone stimulus-frequency otoacoustic emissions: Normative data and methodological considerations. J Acoust Soc Am 143:181 |
| Moleti, Arturo; Sisto, Renata; Shera, Christopher A (2018) Introducing Causality Violation for Improved DPOAE Component Unmixing. AIP Conf Proc 1965: |
| Charaziak, Karolina K; Siegel, Jonathan H; Shera, Christopher A (2018) Spectral Ripples in Round-Window Cochlear Microphonics: Evidence for Multiple Generation Mechanisms. J Assoc Res Otolaryngol 19:401-419 |
| Abdala, Carolina; Ortmann, Amanda J; Shera, Christopher A (2018) Reflection- and Distortion-Source Otoacoustic Emissions: Evidence for Increased Irregularity in the Human Cochlea During Aging. J Assoc Res Otolaryngol 19:493-510 |
| Christensen, Anders T; Abdala, Carolina; Shera, Christopher A (2018) Probing Apical-Basal Differences in the Human Cochlea Using Distortion-Product Otoacoustic Emission Phase. AIP Conf Proc 1965: |
| Sisto, Renata; Shera, Christopher A; Moleti, Arturo (2018) Negative-delay sources in distortion product otoacoustic emissions. Hear Res 360:25-30 |
| Charaziak, Karolina K; Dong, Wei; Shera, Christopher A (2018) Temporal Suppression of Clicked-Evoked Otoacoustic Emissions and Basilar-Membrane Motion in Gerbils. AIP Conf Proc 1965: |
| Shera, Christopher A; Charaziak, Karolina K (2018) Cochlear Frequency Tuning and Otoacoustic Emissions. Cold Spring Harb Perspect Med : |
Showing the most recent 10 out of 71 publications
