PROFILES
Chris Bergevin
The job of an ear is to detect sound: when airborne vibrations pass into a
spiral-shaped structure in the inner ear called the cochlea, thousands of hair
cells vibrate in response and send signals to the brain as neural impulses.
Many people might be surprised to know that
healthy ears emit sounds too. These sounds,
called otoacoustic emissions (OAEs), are believed
to be generated by healthy ears from within the
cochlea and can be measured using a sensitive
microphone placed in the ear canal. In fact, OAE
tests are used routinely in clinical settings, such
as for testing the hearing of newborn babies.
“Scientists have assumed that OAEs are produced
by cellular vibrations in the cochlea, which then
propagate back out through the middle ear,”
said Chris Bergevin (Physics & Astronomy). “But
empirical evidence is weak and the biophysical
principles underlying OAEs are not well understood,
thereby limiting their potential use.”
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Bergevin is taking a comparative approach
to understanding how OAEs are generated
and why animals, including people, also
have a unique spectrum of emissions, like an
acoustic fingerprint. He has studied the ears
of humans, owls and tigers and is now focused
on a type of lizard called the green anole.
“Lizards have remarkable OAEs and their ears are
relatively simple, making them easier to study,”
explained Bergevin. He is collaborating with a team
at SickKids to relate the unique morphology of lizard
ears to their OAE characteristics. He hopes to fill a
major gap in understanding of how OAEs are created.