Improving the Auditory Brainstem Response using Patient-Specific Stimuli
Speaker: Matt Petoe, ITEE
When: 2006-12-13 09:30:00
Venue: 78-224
Host: Andrew P. Bradley
Abstract:The Auditory Brainstem Response (ABR) is a scalp-recorded electrical
response of the brain elicited by acoustic stimuli. They are
composed of several waves (peaks), which relate to the synchronous
electrical activity of the auditory brainstem structures. ABRs are
used for hearing threshold estimation, especially for neonatal
screening, long term monitoring of intensive care unit patients with
traumatic brain injury (TBI), and intraoperative monitoring (IOM)
for any skull base surgery.
The most commonly used acoustic stimuli are short-pulsed 'click'
stimuli, but recent studies have suggested that the click stimulus
does not produce maximal amplitudes of evoked response due to
temporal shifts within the inner ear. These studies have shown that
a rising 'chirp' stimulus produces simultaneous displacement maxima
along the entire length of the basilar membrane, hence achieving
improved neural synchrony. This evokes a larger response for
individual iterations of the ABR and hence can both reduce overall
test times and improve the diagnostic power of the ABR test.
However, in the studies to date, none have investigated the effect
of inter-subject physiology in the choice of chirp
parameters. Instead, researchers have based parameter selection
around data from population ensemble averages, using a
'one-size-fits-all' approach to the problem. Therefore, in this
thesis we will investigate a number of methods for customising the
auditory chirp stimuli to be specific to, and optimised for,
individual test subjects. We will present results from an initial
pilot study showing evidence of increased ABR wave amplitudes when
elicited by subject specific 'custom chirps' as compared to both
conventional click and chirp stimuli. Planned future research will
also be presented investigating how the chirp customisation process
can be both sped-up and made more robust.
Biography:Since completing a Diploma in Audio Engineering in 1997, Matt has
been developing his interests in audio, music, and now audiology. In
2001 he graduated from the University of Auckland with a BSc in
Electronics and Computing and elected to continue with a BE (Hons,
1st Class) at the University of Queensland, graduating in
2005. Currently he is undertaking a doctorate at the University of
Queensland, concerning improvements to the Auditory Brainstem
Response test and Neonatal Hearing Screening.
Type: Ph.D confirmation
Contact:Andrew P. Bradley, seminar host (a.bradley@itee.uq.edu.au)
or Guido Governatori (ITEE seminar co-ordinator)
(guido@itee.uq.edu.au)