• Jill B Firszt, Dawn Burton Koch, Mark Downing, and Leonid Litvak.
• Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St.Louis, Missouri 63110, USA. firsztj@wustl.edu
• Otol. Neurotol. 2007 Aug 1; 28 (5): 629-36.

ObjectiveThe number of spectral channels is the number of discriminable pitches heard as current is delivered to distinct locations along the cochlea. This study aimed to determine whether cochlear implant users could hear additional spectral channels using current "steering." Current steering involves the simultaneous delivery of current to adjacent electrodes, where stimulation can be steered to sites between the contacts by varying the proportion of current delivered to each electrode in an electrode pair. Current steering may increase the number of spectral channels beyond the number of fixed electrode contacts.Study DesignProspective clinical study.SettingTwelve tertiary care centers in North America.PatientsThe subjects were 106 adults with postlingual onset of severe-to-profound hearing loss.InterventionsSubjects received the Advanced Bionics CII or HiResolution 90K device (Advanced Bionics Corporation, Valencia, CA, USA).Main Outcome MeasuresAfter loudness balancing and pitch ranking the 3 electrode pairs (2 and 3, 8 and 9, and 13 and 14), the subjects identified the electrode with the higher pitch while current was varied proportionally between the electrodes in each pair. The smallest change in proportion yielding a discriminable change in pitch was defined as the spectral resolution.ResultsThe data from 115 ears indicate that the number of spectral channels averaged 3.8 for the basal pair, 6.0 for the midarray pair, and 5.3 for the apical pair. Assuming that the number of channels on these 3 electrode pairs represents the entire array, the total potential number of spectral channels was calculated and ranged from 8 to 451, with an average of 63.ConclusionThese results indicate that additional pitch percepts can be created using current steering.

20 keywords...

hide…