As a researcher, my training is in auditory physiology, particularly the middle ear and cochlea, neuroscience, and acoustics. As an audiologist, I also have strong clinical interests. My research program focuses primarily on understanding the mechanics of the peripheral auditory system and applying that understanding in clinically useful ways. One of the main tools I use in my research is the measurement of otoacoustic emissions (OAEs), which are very low-level sounds produced in the cochlea.

Because otoacoustic emissions (OAEs) are generated by processes inside the cochlea, they play an important role in non-invasive measurement of hearing status. Until recently, most OAE measurements have been made at relatively low frequencies, due to technical limitations. This has limited our understanding of high-frequency areas of the cochlea. Some of my work has therefore focused on using innovative measurement techniques to enable measurement of high-frequency OAEs. Software adjustments can be used to overcome some of the current hardware limitations. I have described these techniques in some of my publications, and I have written my own custom software package implementing these adjustments. In addition to using the software for my own research, my software has been or is currently used in other research laboratories. Calibration of high-frequency stimuli has been another technical limitation. Recently, a new calibration technique has been proposed to overcome this limitation, and I have worked with several prominent researchers in this area, along with PhD students in my lab, to arrive at potential solutions.

  1. Mertes IB and Goodman SS (2013) Short-latency transient-evoked otoacoustic emissions as predictors of hearing status and thresholds. Journal of the Acoustical Society of America, 134(3), 2127-2135.
  2. Scheperle RA, Goodman SS, and Neely ST (2011) Further assessment of forward pressure level for in situ calibration. J. Acoust. Soc. Am., 130(6), 3882–3892.
  3. Keefe DH, Goodman SS, Ellison JE, Fitzpatrick DF, and Gorga MP (2011) Detecting high-frequency hearing loss with click-evoked otoacoustic emissions. Journal of the Acoustical Society of America, 129, 245-261.
  4. Goodman SS, Ellison JE, Fitzpatrick DE, Jesteadt W, and Keefe DH (2009) High-frequency click-evoked otoacoustic emissions and behavioral thresholds in humans. Journal of the Acoustical Society of America, 125, 1014-1032.

Some of my early work on one particular type of OAE, Transient-Evoked (TEOAE), used modified techniques to enable measurements at high frequencies and short latencies. Somewhat unexpectedly, in addition to successfully measuring high frequencies, I also measured packets of energy occurring much earlier in time than anticipated, even at lower frequencies. Little, if any attention had been previously paid to these early components, presumably because they were not visible using older measurement techniques. As a result, they had not played a role in theories of OAE generation and the mechanical cochlear processes underlying them. An important thrust of my research has been elucidating where in the cochlea these early components are generated and what the generation mechanism is.

  1. Lewis JD and Goodman SS (2015) Basal Contributions to Short-Latency Transient-Evoked Otoacoustic Emission Components. Journal of the Association for Research in Otolaryngology, 16(1):29-45.
  2. Lewis JD and Goodman SS (2014) The Effect of Stimulus Bandwidth on the Nonlinear-Derived Tone-Burst-Evoked Otoacoustic Emission. Journal of the Association for Research in Otolaryngology, 15(6), 915-931.
  3. Goodman SS, Mertes IB, Scheperle RA. (2011) “Delays and growth rates of early and late TEOAE components”. What Fire is in Mine Ears: Progress in Auditory Biomechanics.  AIP Conf. Proc., 1403, 279-285.

Growing out of my work on high-frequency TEOAEs has been research on measuring the effects of efferent neural activation on cochlear function. In noisy situations, an efferent feedback system in the auditory pathway modifies cochlear vibration patterns. These modifications enhance our ability to hear speech in noise and may be associated with protection from noise-induced hearing loss. The modified vibration patterns can be measured using OAEs. My work in this area extends measurement of efferent effects to high frequencies, where the neural innervation patterns in humans are not well understood.  This work has implications for predicting susceptibility to noise-induced hearing loss. Most previous work in this area has relied on group data to show effects. In contrast, my research focuses on measuring statistically significant effects in individual subjects, an important first step if these types of measurements are to find clinical use in the future.

  1. Mertes IB and Goodman SS. (2015) Repeatability of  Medial Olivocochlear Efferent Effects on Transient-evoked Otoacoustic Emissions. Ear and Hearing, Epub ahead of print.
  2. Goodman SS, Lewis JD, Mertes IB, and Weissbeck DK (2013) Medial olivocochlear-induced transient-evoked otoacoustic emission amplitude shifts in individual subjects. Journal of the Association for Research in Otolaryngology, 7, 125-139.
  3. Goodman SS and Keefe DH (2006) Simultaneous measurement of noise-activated middle-ear muscle reflex and stimulus frequency otoacoustic emissions. Journal of the Association for Research in Otolaryngology, 7, 125-139.


Auditory Research Laboratory
Dr. Shawn S. Goodman, Director
341 Wendell Johnson Speech and Hearing Center
The University of Iowa
Iowa City IA 52242