Correction to: Effect of Stimulus Polarity on Detection Thresholds in Cochlear Implant Users: Relationships with Average Threshold, Gap Detection, and Rate Discrimination.

The middle initial of Julie G. Arenberg's name was incorrect in the original publication; it is correct as displayed here.

Effect of Stimulus Polarity on Detection Thresholds in Cochlear Implant Users: Relationships with Average Threshold, Gap Detection, and Rate Discrimination.

Previous psychophysical and modeling studies suggest that cathodic stimulation by a cochlear implant (CI) may preferentially activate the peripheral processes of the auditory nerve, whereas anodic stimulation may preferentially activate the central axons. Because neural degeneration typically starts with loss of the peripheral processes, lower thresholds for cathodic than for anodic stimulation may indicate good local neural survival. We measured thresholds for 99-pulse-per-second trains of triphasic (TP) pulses where the central high-amplitude phase was either anodic (TP-A) or cathodic (TP-C).

A Dynamically Focusing Cochlear Implant Strategy Can Improve Vowel Identification in Noise.

Objectives: The standard, monopolar (MP) electrode configuration used in commercially available cochlear implants (CI) creates a broad electrical field, which can lead to unwanted channel interactions. Use of more focused configurations, such as tripolar and phased array, has led to mixed results for improving speech understanding. The purpose of the present study was to assess the efficacy of a physiologically inspired configuration called dynamic focusing, using focused tripolar stimulation at low levels and less focused stimulation at high levels.

Rate discrimination, gap detection and ranking of temporal pitch in cochlear implant users.

Cochlear implant (CI) users have poor temporal pitch perception, as revealed by two key outcomes of rate discrimination tests: (i) rate discrimination thresholds (RDTs) are typically larger than the corresponding frequency difference limen for pure tones in normal hearing listeners, and (ii) above a few hundred pulses per second (i.e. the "upper limit" of pitch), CI users cannot discriminate further increases in pulse rate.

Examining the electro-neural interface of cochlear implant users using psychophysics, CT scans, and speech understanding.

This study examines the relationship between focused-stimulation thresholds, electrode positions, and speech understanding in deaf subjects treated with a cochlear implant (CI). Focused stimulation is more selective than monopolar stimulation, which excites broad regions of the cochlea, so may be more sensitive as a probe of neural survival patterns. Focused thresholds are on average higher and more variable across electrodes than monopolar thresholds.

Multipolar current focusing increases spectral resolution in cochlear implants.

Cochlear implants are highly successful neural prostheses that restore hearing in the deaf, often resulting in high levels of speech understanding in quiet listening conditions. In more challenging conditions, however, cochlear implant subjects often score much lower than their normal-hearing peers, possibly reflecting limits of the electrode-neural interface. In this study, we compare monopolar stimulation versus focused stimulation, using multipolar channels, to test if current focusing can increase spectral resolution.

Genetic algorithms for adaptive psychophysical procedures: recipient-directed design of speech-processor MAPs.

Objectives: The goal of the research is to evaluate the application of genetic algorithms (GAs) in listener-directed optimization of audio-processing designs. We hypothesize that cochlear-implant recipients can use a GA-guided adaptive psychophysical search procedure to select useful designs from among a large number of speech processor MAPS.

Design: An adaptive psychophysical procedure was developed in which a listener's preferred four out of eight speech processor MAPs were updated according to a genetic algorithm.