Abstract
Objectives:
Compare MED-EL fine structure processing (FSP) and high-definition continuous interleaved sampling (HDCIS) in discrimination of musical instrument harmonic changes.
Methods:
Twelve MED-EL users were programmed with novel FSP and HDCIS maps. With each map they underwent discrimination testing of paired sound stimuli. The stimuli were native and harmonically-manipulated sound clips of a single note played by an instrument. The instruments tested were the trumpet, alto saxophone, and tuba. The harmonic manipulations consisted of removal of either the first or second harmonic. Discrimination was quantified by calculating d′; higher d′ values indicated better performance.
Results:
There were no significant differences in discrimination performance between FSP and HDCIS across conditions. However, for both strategies, significant differences in discrimination were observed between discrimination of the first and the second harmonic manipulation conditions for the trumpet and the tuba. For trumpet, significantly better performance was observed with removal of the second harmonic (d′ = 1.57) compared with removal of the first harmonic (d′ = 0.58; P < .05). For tuba, the opposite was observed (first d′ = 1.12, second d′ = 0; P < .05). Discrimination of the saxophone stimuli was significantly more difficult compared to the other instruments, which was likely related to the saxophone harmonics’ close frequency/channel proximity.
Conclusions:
Results from this novel-map study did not show a difference in harmonic cue discrimination between FSP and HDCIS. Evidence was found regarding important harmonic information for individual instruments tested. Perception of harmonic cues could be affected by channel discrimination. These results can be used to improve cochlear implant signal processing strategy.
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