Conditioning pulse trains in cochlear implants: effects on loudness growth.
OBJECTIVE
The addition of a high-rate (5 kpps) conditioning pulse train to the input signal of cochlear implants will result in shallower loudness growth across the dynamic range of cochlear implant patients.


BACKGROUND
High-rate conditioning pulse trains have been shown to increase the dynamic range of sinusoidal stimuli for cochlear implant recipients in a manner consistent with stochastic resonance. This study further characterizes the effects of conditioning stimuli on loudness by examining the loudness growth functions for sinusoidal stimuli both with and without conditioning.


METHODS
Seven post-lingually deafened adults using the Clarion CII cochlear implant participated in this study. The loudness growth functions of each subject were characterized using sinusoidal stimuli, both with and without the presence of a high-rate conditioner. Loudness was measured using magnitude estimation.


RESULTS
The loudness growth functions of all seven subjects demonstrate an increase in dynamic range for sinusoidal stimuli with the addition of the conditioning pulse train. Shallower loudness growth is seen across the dynamic range with the addition of a conditioner. This result was shown for loudness growth fitted to exponential, power, and cumulative gaussian functions.


CONCLUSIONS
The addition of high-rate conditioning pulse trains to sinusoidal stimuli presented to cochlear implant recipients results in larger dynamic ranges, with more gradual increases in loudness growth across the dynamic range. This suggests that signal-processing strategies incorporating conditioning may be clinically useful, requiring less compression of the input signal and leading to less distortion perceived by cochlear implant patients.
Hong
Robert S
RS
Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, USA.
Rubinstein
Jay T
JT
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003054:Cochlear Implants; D012048:Correction of Hearing Impairment; D003638:Deafness / Q000534:rehabilitation*; D004558:Electric Stimulation; D005260:Female; D006309:Hearing; D006801:Humans; D008144:Loudness Perception / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D016011:Normal Distribution; D016896:Treatment Outcome