Karl Grosh
University of Michigan, MI·Biomedical Engineering
Hearing depends on a chain of mechanical events: sound moves the small bones of the middle ear, which drive fluid motion in the cochlea, the spiral inner-ear organ that converts vibration into nerve signals. Two projects work on either side of that chain.
- Fields
Biomedical Engineering
Engineering
Physiology
- Topics
cochlear mechanics
auditory prosthesis
cochlear implant
- Grants
- 2 known grants, through Apr 2029
What they work on
- Design and fabricate a multi-resonant piezoelectric MEMS accelerometer co-designed with an application-specific integrated circuit, and reach a 5-milligram packaged implantable sound sensor using flip-chip packaging that eliminates printed circuit board mounting.
- Characterize acoustic sensitivity and noise floor of the packaged accelerometer through benchtop calibration and by implanting it in male and female cadaveric temporal bone preparations under acoustic stimulation.
- Compare attachment locations along the ossicular chain, the middle-ear bones, to minimize disturbance of middle-ear mechanics, ease surgical implantation and maximize sensitivity to both translation and rotation.
- Quantify cochlear vibration in the absence of sound to establish the noise floor and test theories of the cochlear amplifier driven by outer hair cell motility.
- Predict cochlear responses to simple and complex sounds with coupled fluid–mechanical–electrical models, testing rate-dependent effects in mechano-electric transducer channel models, including adaptation, and in outer hair cell electromechanics.
- Determine how mechanical attachment of inner hair cell hair bundles to the tectorial membrane, the gel overlying the sensory cells, shapes cochlear excitation, and validate predictions against existing and newly designed experiments.
More about the research
One builds tiny implantable sensors that could replace the external microphone of a hearing aid or cochlear implant. The other builds mathematical models of how the healthy cochlea amplifies and sharpens sound, and of how it fails.
Why it matters
Hearing aids and cochlear implants with all parts hidden inside the body could allow continuous use, be safer and more cosmetically acceptable, and exploit the outer ear's natural directional cues, potentially expanding who is willing to use them. A predictive cochlear model could identify which inner-ear structures fail with loud sound or age, support noninvasive hearing diagnostics that link response abnormalities to specific pathologies, and inform better speech-processing or cochlear-implant stimulation algorithms.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Jong-Hoon Nam
University of Rochester, NY·Biomedical Engineering
Measure how length changes in outer hair cells deflect the stereocilia, the hair-like sensors on hair cells, using in vitro cochlear preparations where individual outer hair cells are controlled electrically, chemically and mechanically.
Joseph Santos-Sacchi
Yale University, CT·Biophysics
Determine the cryo-EM structure of prestin, the outer hair cell motor protein behind cochlear amplification, in the expanded state that voltage brings about, complementing the known contracted-state structure.
R. Burger
Lehigh University, PA·Neuroscience
Test whether overexpressing BMP7, a signaling protein that patterns the early ear, repatterns the frequency tuning of hair cells in the chick inner ear toward low-frequency types.
The school
University of Michigan: 124 labs on PI Pages, $2.1B a year on research, 963 research doctorates a year.
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