Effects of age and background noise on processing a mistuned harmonic in an otherwise periodic complex sound
Hearing Research
Older adults presented with short (i.e., 40 ms) harmonic complex tones show a reduced likelihood of
hearing the mistuned harmonic as a separate sound. Here, we examined whether this age difference for
the mistuned harmonic would generalize to a longer signal duration (i.e., 200 ms). We measured
auditory evoked fields (AEFs) using magnetoencephalography while young and older adults were presented
with harmonic complex tones that either had all partials of the tones in tune (single sound object)
or contained a 4 or 16% mistuned harmonic (dual sound objects). The auditory stimuli were presented in
isolation or embedded in low or moderate levels of continuous white noise. For each participant, we
modeled the AEFs with a pair of dipoles in the superior temporal plane and examined the effects of age
and noise on the amplitude and latency of the resulting source waveforms. The present study reveals
similar noise-induced increases in N1m and object-related negativity in young and older adults which
may be mediated via efferent feedback connections and/or changes in the temporal window of integration.
We observed less age-related differences in concurrent sound segregation for stimuli that
matched the duration of the temporal integration window of auditory perception (i.e.,w200 ms) than for
short duration sounds (i.e., 40 ms). Possible explanations for this duration-dependent age-related decline
in concurrent sound perception are a general slowing in auditory processing and/or lengthening of the
temporal integration window.
283
2012
126-135
Alain C., McDonald K., Van Roon P. &
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