We are generally interested in hearing, hearing loss, and hearing healthcare. One major focus of our work is in understanding the physiology and biophysics related to sounds created in the inner ear (otoacoustic emissions). We record these sounds using small microphones placed in the ear and attempt to understand the workings of the inner ear by analyzing them in various ways. We are also keenly interested in using these sounds to detect malfunction of the ear at the earliest. A second major focus is on hearing healthcare delivery. Here we are interested in understanding why so few people seek hearing health care. Once we identify barriers to access, we attempt to devise tools and methods to remove these barriers, thereby improving the affordability and accessibility of hearing health care.


Cochlear Mechanics and OAEs

Otoacoustic emissions (OAEs) provide a convenient noninvasive window into cochlear mechanics. OAEs also provide a tool that can be applied uniformly across species to explore and understand commonalities and differences. Finally, OAEs are ideally suited for clinical applications across all ages. Our study of OAEs as a window into cochlear mechanics forms the foundation upon which we build our applied research enterprise. In this specific area we are interested in how OAEs are generated and how they propagate out from the cochlea to the outer ear. We have investigated the origin of what has become known as cochlear fine structure or microstructure. The ultimate goal is to understand the normal function of the cochlea and then apply this knowledge to build accurate and sensitive clinical tools for detection of cochlear malfunction. Funded by NIH/NIDCD; ASHA Foundation; Knowles Hearing Center; American Hearing Research Foundation
  1. Glavin, CC, Dhar, S, Goodman, SS(2023)Measurement of swept level distortion product otoacoustic emission growth functions at multiple frequencies simultaneously. JASA Express Lett 3 (6):.
  2. Glavin, CC, Siegel, J, Dhar, S(2021)Distortion Product Otoacoustic Emission (DPOAE) Growth in Aging Ears with Clinically Normal Behavioral Thresholds. J Assoc Res Otolaryngol 22 (6):659-680.
  3. Wilson, US et al.(2021)Cochlear tuning estimates from level ratio functions of distortion product otoacoustic emissions. Int J Audiol 60 (11):890-899.
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Hearing Across the Lifespan

From before birth through every day of our lives, we count on our acute sense of hearing for life-critical functions. In this line of work we study the maturation and aging of hearing through the human lifespan. In particular we are interested in the changes in inner ear (cochlea) function. Over the last few years we have collaborated with developmental scientist Carolina Abdala (University of Souther California) to study the maturation of inner ear function in premature and term infants. In another collaboration with Northwestern colleague Jonathan Siegel, we have evaluated changes in inner ear function during middle age. While this major focus in our laboratory continues to reveal interesting new knowledge, we have already demonstrated remarkable changes in inner ear function much earlier in life than previously known. Our results seem to suggest that the human inner ear starts to show signs of age-related changes as early as the third decade of life and these changes accelerate in the next twenty years. This work has profound implications on when and how to deliver hearing health care. These findings also shed new light on the timeline of auditory aging.
  1. Poling, GL, Siegel, JH, Lee, J, Dhar, S(2022)The influence of self-reported noise exposure on 2ƒ12 distortion product otoacoustic emission level, fine structure, and components in a normal-hearing population. J Acoust Soc Am 151 (4):2391.
  2. Glavin, CC, Siegel, J, Dhar, S(2021)Distortion Product Otoacoustic Emission (DPOAE) Growth in Aging Ears with Clinically Normal Behavioral Thresholds. J Assoc Res Otolaryngol 22 (6):659-680.
  3. Cornwell, T et al.(2020)Walking With Ears: Altered Auditory Feedback Impacts Gait Step Length in Older Adults. Front Sports Act Living 2 :38.
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Hearing Healthcare

Hearing loss is incredibly prevalent, with one-in-three adults over the age of 65 suffering from disabling hearing loss, and even larger numbers experiencing mild or moderate loss. Along with collaborators at Northwestern University, University of Texas and the Mayo Clinic we are investigating health care for this growing population of individuals with hearing loss. We are seeking to improve access to care by removing barriers to entry, such as the medical waiver needed to purchase a hearing aid. Furthermore, we are developing research that will address the gaps in knowledge about hearing health care, focusing particularly on unrecognized barriers to care and the costs associated with the ongoing epidemic of hearing loss. Funded by NIH/NIDCD
  1. Klyn, NAM, Letendre, C, Shrestha, N, Lambert, BL, Dhar, S(2021)Interpretability of the audiogram by audiologists and physician non-specialists. Int J Audiol 60 (2):133-139.
  2. Klyn, NAM et al.(2019)CEDRA: A Tool to Help Consumers Assess Risk for Ear Disease. Ear Hear 40 (6):1261-1266.
  3. Kleindienst, SJ et al.(2018)Errors in Items and Algorithm in Questionnaire Used in Validation Study. JAMA Otolaryngol Head Neck Surg 144 (5):462.
  4. Klyn, NAM et al.(2018)A Retrospective Estimate of Ear Disease Detection Using the "Red Flags" in a Clinical Sample. Ear Hear 39 (5):1035-1038.
  5. Kleindienst, SJ et al.(2017)Development and Initial Validation of a Consumer Questionnaire to Predict the Presence of Ear Disease. JAMA Otolaryngol Head Neck Surg 143 (10):983-989.
  6. Kleindienst, SJ et al.(2016)Identifying and Prioritizing Diseases Important for Detection in Adult Hearing Health Care. Am J Audiol 25 (3):224-31.
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Participate in Research

We are looking for research participants between 7 and 79 years of age. Our projects typically require filling out questionnaires and participating in measurements of your hearing. The hearing tests are all done using regular earbuds much like the kind you might use to listen to a music player or phone.
Learn More About Participating

Tools For All


The Consumer Ear Disease Risk Assessment is a questionnaire to be used by seekers of hearing aids. The questionnaire gives you a risk score to help you determine whether you should see a physician or audiologist before purchasing hearing aids to rule out other ear diseases.


Sumitrajit (Sumit) Dhar

Sumitrajit (Sumit) Dhar

Principal Troublemaker

Sumit’s scientific interests include otoacoustic emissions, cochlear mechanics, and hearing health care.

Mary Meskan

Mary Meskan

Assistant Instigator

Mary is an audiologist with clinical and research experience.  Her interests include improving access to hearing healthcare.

Jasleen Singh

Jasleen Singh

Postdoctoral Fellow
Jasleen is a clinically trained audiologist. Her scientific interests include making hearing aid technologies more accessible to older adults, and improving access to hearing healthcare.
Courtney Coburn Glavin

Courtney Coburn Glavin

PhD Student

Courtney is a clinically trained audiologist. She is interested in using otoacoustic emissions to better understand how the ear changes with age and in response to environmental insults.

Anna Pitman

Anna Pitman

Research Study Coordinator
Anna is the Research Study Coordinator for the lab’s P-CHAT study. Her research interest at the lab is improving access to hearing healthcare.
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BibCat is our internal library of papers we have read.

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Contact Us

Address: Auditory Research Laboratory; 2240 Campus Drive, Evanston, Illinois 60208
Phone: 847 467 0123