Project Background
Auditory perception depends on the acoustic characteristics of a given sound and brain processing that shapes the neural representation of that sound. The brain controls the response of the sensory organ of hearing (i.e., the cochlea) through efferent neural pathways. Efferent pathways send information from the brain to the peripheral nervous system, including sensory systems. The medial olivocochlear (MOC) reflex includes efferent pathways that control how much the cochlea amplifies certain aspects of incoming sounds. This efferent pathway is likely influenced by attention and therefore may facilitate hearing during challenging listening environments like understanding speech in a noisy background. We will assess the effect of the MOC reflex on human auditory nerve responses using a custom-made sensor. The reflex will be evoked by presenting noise to the opposite ear from which measurements are recorded. Results from this study will demonstrate that human auditory nerve responses are affected by efferent pathways and provide evidence that such effects have the capacity to influence hearing in noisy backgrounds. These findings will pave the way for clinical assessment of auditory efferent pathways and the identification of pathologies that lead to difficulty understanding speech in background noise among adults with hearing loss.
Student Role
Student research assistants will participate in the design, execution, analysis, and publication of research. Primarily responsibilities will include running and documenting data collection sessions, summarizing data collected in tables and figures, summarizing research findings in reports written to the lab manager, and reviewing/discussing pertinent literature on the project. Data collection for perceptual experiments will involve working with a customized graphical user interface in Matlab to quantify the sensitivity of human participants to specific features of sound.
Student Learning Outcomes and Benefits
Skyler Jennings
The long-term goal of my research is to understand how the auditory system and brain process sound in noisy backgrounds to achieve robust speech understanding. My current projects center on the hypothesis that efferent feedback automatically calibrates the auditory system to the ever-changing acoustic soundscape. This hypothesis predicts that individuals with cochlear hearing impairment suffer from an inability to adapt to new acoustic environments, since loss of outer hair cell (OHC) function is expected to negatively influence an important efferent subsystem called the medial olivocochlear (MOC) reflex. Despite physiological evidence linking MOC activity to improved signal-to-noise ratios, behavioral studies in humans have yet to provide compelling results to support this claim. This lack of evidence provides the impetus for my recent research interests and activities.
Mentoring Philosophy
My teaching philosophy is summarized in three statements: 1) be a chef, not a cook!, 2) understand the graphs, and 3) rise to the challenge.
Be a chef, not a cook!: I found the major difference between student "chefs" and "cooks" is the ability to master concepts rather than master facts. I teach concepts in hearing science by packaging them into a model or framework. I introduce and develop these models through examples, figures, drawings, formulas, and succinct summary statements.
Understand the graphs: Data is at the heart of the concepts and models in hearing science. Analyzing a graph is an essential skill for learning new ideas and refining the models and frameworks that drive research.
Rise to the challenge: I believe the rigor and quality of education is substantially increased when instructors facilitate in-depth learning and "raise the bar" on academic performance in these areas. My experience is that students will rise to the instructor's expectations if the appropriate support structure is in place. I challenge students with advanced topics in acoustic impedance, signals and systems, Fourier analysis, cochlear physiology, models of the auditory periphery, and psychophysical models of auditory perception. I support students with these challenges by carefully designing assignments, being responsive to email and face-to-face communication, and facilitating interaction with other research assistants. Students in my lab benefit from mentoring activities such as guided literature reviews, impromptu whiteboard discussions, mini-teaching/discussion sessions during lab meetings, and brainstorming sessions about research and how to improve the lab where students are full and valued participants.