Measurement of the electrically evoked compound action potential via a neural response telemetry system

The main aim of this study was to validate a new technique, neural response telemetry (NRT), for measuring the electrically evoked compound action potential in adult cochlear implant users via their Nucleus C124M implant. Thirty-eight adults were evaluated with a variety of measurement procedures with the NRT software. Electrically evoked compound action potentials were obtained in 31 of the 38 adults (81.6%) and in 132 of the 160 electrodes (82.5%) tested. In addition to validating this technique, we also established a set of default clinical test parameters

Effects of stimulation configurations on place pitch discrimination in cochlear implants

The present study aimed to examine the effect of electrode configuration, specifically monopolar (MP) or bipolar (BP) stimulation, on place pitch discrimination in cochlear implants (CIs). Twelve subjects implanted with the Nucleus Freedom device were presented with various pairs of stimulation across the electrode array, with varying degrees of distance between stimulation sites, and asked to judge the higher of the two in pitch. Each pair was presented either in the same mode or in different modes of stimulation for the within-mode or across-mode condition, respectively, at least 20 times. The result of the within-mode condition revealed that subjects, on average, were able to discriminate pitches significantly better in MP than in BP, with the sensitivity index (d′) for adjacent channels of 1.2 for MP and 0.8 for BP. The result of the across-mode condition revealed that while individual variability existed, there was a strong tendency for CI subjects to perceive a higher pitch in BP stimulation than in MP for a similar site of stimulation. In other words, an MP channel needed to be shifted in a basal direction by as much as two electrodes on average to elicit a pitch comparable to that of a BP channel

Performance and preference for ACE stimulation rates obtained with nucleus RP 8 and freedom system

Cochlear recently released the Nucleus Freedom System which has been based on the Nucleus Research Platform 8. Both systems make use of the same implant, the CI24RE, which includes expanded total stimulation rates up to 32 kHz. In this study the performance of the ACE strategy at 500, 1200 and 3500 pps/channel was investigated using an ABC-CBA design. At the end of each period speech tests were performed. In the CBA phase the patients completed a comparative questionnaire to determine the subjective rate preference. Preliminary results in 13 recipients indicate no differences in for the ACE strategy at rates ranging from 500 pps to 3500 pps/channel