Stimulus specific adaptation in humans using DPOAE measurements
This study aims
to investigate the phenomenon of stimulus-specific adaptation (short: SSA) by
measuring distortion-product otoacoustic emissions (short: DPOAE) in the human
otoacoustic emissions can be evoked by a two-tone stimulation and are well
detectable with a microphone in front of the tympanum. DPOAE are produced by
nonlinear mechanical amplification of low level sound in the cochlea and can be
used as a tool to derive cochlear sensitivity and sharpness of cochlear
frequency tuning. Stimulus-specific adaptation refers to a reduction in the
response of a neuron to a repeatedly presented sound stimulus. At the same
time, it remains sensitive to rarely presented sounds (Ulanovsky et al 2003).
SSA has already been detected in humans by EEG-Measurements (Briley et al.
2013), but there is a lack of knowledge about the underlying neuronal mechanisms.
experiments, we were able to detect frequency-specific, as well as
level-dependent amplifications of the SSA effect (also by measuring DPOAE) in
anaesthetized rodents. The main aim of this study is to extend these findings on
awake humans. It will be further investigated whether SSA can possibly
influence the subjective loudness perception.
measurements the participants are sitting in a comfortable chair in a
sound-proof chamber. The coupler, which contains the microphone and two
speakers, is placed in front of the tympanum, similar to in-ear headphones. The
sound levels of the used sound stimuli do not exceed 80 dB SPL and correspond
therefore to the volume range from soft to loud speech. Thus, the presented
stimuli cannot cause sound-damage to the ear.
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