• Dobie, Robert A (PI)

Project: Research project

Project Details


Short-latency auditory responses can be derived by cross-correlation of
continuous pseudorandom noise stimuli with averaged scalp responses in both
humans and experimental animals. Data are acquired very rapidly, and
responses to specific spectral regions of the stimulus can be derived
off-line. The method detects only frequency-following potentials and is
most sensitive to low and middle frequencies. It is thus complementary to
conventional auditory brainstem responses, which detect onset responses and
are most sensitive to high stimulus frequencies. A series of studies in
human subjects is proposed, withthe ultimate goal of developing a rapid and
effective method for clinical assessment of auditory thresholds, i.e.,
audiogram estimation. Parametric studies will determine optimal ranges for
stimulus/response duration and averaging time. Broadband masking,
replicating previous studies in guinea pigs, will determine the
contribution of cochlear microphonics in the earliest part of the response,
while studies using deaf subjects will provide an estimate of stimulus
artifact at high stimulus levels. High-pass masking studies will determine
the extent to which basal cochlear loci contribute to responses to low
frequencies. Low-pass masking will estimate the degree to which
low-frequency stimulus components interfere with basally-generated
responses to higher frequencies. Patients with low-frequency and
high-frequency hearing loss will be tested to determine whether the
thresholds for cross correlation functions in the corresponding spectral
regions are appropriately elevated. The effects of sedation will also be
studied. Finally, an objective method of threshold estimation using
coherence functions will be compared to simple inspection of replicated
cross-correlation functions. A protocol will be developed which can
subsequently be tested in patients with hearing loss, and in sleeping or
sedated children.
Effective start/end date7/1/866/30/90


  • National Institutes of Health


  • Medicine(all)
  • Neuroscience(all)


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