Elizabeth S. Olson, PhD

The cochlea, the auditory inner ear, receives the auditory stimulus, which has been transduced by the middle ear from acoustic pressure to fluid displacement at one of the cochlea’s windows, and converts it into a spike code in the auditory nerve.  Within the cochlea, the auditory stimulus is sorted by frequency along the long, narrow strip of sensory tissue that spirals within the snail-shaped bony capsule of the cochlea.  The frequency sorting is fundamentally achieved by the basic physics of the sensory tissue — stiffness of the tissue and inertia of the fluid, which produces a displacement and pressure wave that travels from the cochlea’s input window to the deepest locations along the cochlear spiral, peaking at frequency-dependent locations.  Molecular forces within the sensory hair cells that line the sensory tissue boost the wave’s amplitude by factors of many hundreds, and sharpen the frequency resolution.  This active boosting is termed the “cochlea amplifier.”  My lab studies how the cochlear amplifier works, with measurements of nanoscale sensory tissue motion, hair cell electrical responses, and intracochlear pressures, at frequencies up to and above 50 kHz.  A second area of focus is the development of an implantable microphone for a totally implanted cochlear implant, using a piezoelectric polymer as the pressure-sensing element.  We collaborate with Barnard and Columbia faculty in Biochemistry and Electrical Engineering, and  Engineering and Neurophysiology groups in the US and the UK.