The timbre perception of cochlear implantees (CI) is poor compared to normal hearing
(NH) listeners. The cues that are normally transmitted to NH listeners may be less salient
or even absent for CI users. From the literature, two spectral (brightness (Tb) and
irregularity (IRR)) and two temporal timbre parameters (log rise-time (LRT) and
sustain/decay (S/D) parameter (n)) have been identified as important timbre parameters.
Each of these parameters was extracted for a set of thirteen instruments. Sounds could be
resynthesized according to the specific timbre parameter set. The variation of loudness,
pitch and perceived duration as functions of the timbre parameters were investigated to
provide systematic balancing methods.
The just-noticeable differences (JNDs) were obtained for each of the parameters for
thirteen instruments for NH listeners and a reduced instrument set of nine instruments for
the CI users using a 1-up, 2-down, two-alternative, forced choice procedure. From the
JNDs, predicted confusion matrices were constructed. From the confusion matrices, a
feature information transmission analysis (FITA) indicated the salience of each of the
parameters and NH and CI results could be compared.
Dissertation (MEng)--University of Pretoria, 2011.