title: Effects of phase duration and electrode separation on loudness growth in cochlear implant listeners.
abstract: Loudness estimates were obtained in a group of four adult subjects implanted with the Nucleus-22 multielectrode cochlear implant device, for a range of pulse amplitudes and different fixed phase durations and electrode separations. The stimulus was a 200-ms long train of biphasic pulses presented at 500 pulses/s. Subjects estimated loudness as a number from 0 ("don't hear it") to 100 ("uncomfortably loud"). Loudness was found to grow exponentially with pulse amplitude, at a rate that was dependent upon the phase duration as well as the electrode separation. An equation of the form L = e(lambda + gamma M)(D theta)I, where L is the estimated loudness, M is the separation between electrodes of a stimulating pair, D is the phase duration, I is current amplitude, and lambda, gamma, and theta are constants, appears to describe the observed data adequately. The findings are remarkably consistent across subjects.
authors.affiliation: Department of Auditory Implants and Perception, House Ear Institute, Los Angeles, California 90057, USA. monita@hei.org
authors.forename: M
authors.initials: M
authors.lastname: Chatterjee
authors.forename: Q J
authors.initials: QJ
authors.lastname: Fu
authors.forename: R V
authors.initials: RV
authors.lastname: Shannon
mesh_terms: D000328:Adult; D000368:Aged; D019929:Cochlear Implantation; D004566:Electrodes; D006801:Humans; D008144:Loudness Perception / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D013067:Speech Perception / Q000502:physiology; D013997:Time Factors