Full-array channel discrimination in cochlear implants: validation and clinical application.

Objective: We sought to validate our proposed tool for estimating channel discrimination of cochlear implant (CI) users along the full electrode array and to assess associations between place-pitch discrimination and speech perception.

Design: In two tests, participants identified one stimulus (probe) as the odd-one-out compared with two reference stimuli. Probe stimuli were evoked using dual electrode stimulation characterised by the current steering coefficient α.

The effect of stimulus level on excitation patterns of individual electrode contacts in cochlear implants.

Objective: Spread of excitation (SOE) in cochlear implants (CI) is a measure linked to the specificity of the electrode-neuron interface. The SOE can be estimated objectively by electrically evoked compound action potential (eCAP) measurements, recorded with the forward-masking paradigm in CI recipients. The eCAP amplitude can be plotted as a function of the roving masker, resulting in a spatial forward masking (SFM) curve.

Unravelling the temporal properties of human eCAPs through an iterative deconvolution model.

Objective: The electrically evoked compound action potential (eCAP) has been widely studied for its clinical value in evaluating cochlear implants (CIs). However, to date, single-fiber recordings have not been recorded from the human auditory nerve, and many unknowns remain about the firing properties that underlie the eCAP in patients with CIs. In particular, the temporal properties of auditory nerve fiber firing might contain valuable information that may be used to estimate the condition of the surviving auditory nerve fibers.

Effectiveness of Phantom Stimulation in Shifting the Pitch Percept in Cochlear Implant Users.

Objectives: Phantom electrode stimulation was developed for cochlear implant (CI) systems to provide a lower pitch percept by stimulating more apical regions of the cochlea, without inserting the electrode array deeper into the cochlea. Phantom stimulation involves simultaneously stimulating a primary and a compensating electrode with opposite polarity, thereby shifting the electrical field toward the apex and eliciting a lower pitch percept. The current study compared the effect sizes (in shifts of place of excitation) of multiple phantom configurations by matching the perceived pitch with phantom stimulation to that perceived with monopolar stimulation.

Test/Retest Variability of the eCAP Threshold in Advanced Bionics Cochlear Implant Users.

Objective: The reliability of the electrically evoked compound action potential (eCAP) threshold depends on its precision and accuracy. The precision of the eCAP threshold reflects its variability, while the accuracy of the threshold shows how close it is to the actual value. The objective of this study was to determine the test/retest variability of the eCAP threshold in Advanced Bionics cochlear implant users, which has never been reported before.

Channel discrimination along all contacts of the cochlear implant electrode array and its relation to speech perception.

Objective: To test the channel discrimination of cochlear implant (CI) users along all contacts of the electrode array and assess whether this is related to speech perception.

Design: CI recipients were tested with a custom-made channel discrimination test. They were asked to distinguish a target stimulus from two reference stimuli in a three-alternative forced choice (3AFC) task.

The Precision of eCAP Thresholds Derived From Amplitude Growth Functions.

Objective: An amplitude growth function (AGF) shows the amplitude of an electrically evoked compound action potential (eCAP) as a function of the stimulation current. AGFs can be used to derive the eCAP threshold, which represents the minimum amount of current needed to elicit a measurable eCAP. eCAP thresholds have been widely used clinically to, for example, assist with sound processor programming.

Use of Electrically Evoked Compound Action Potentials for Cochlear Implant Fitting: A Systematic Review.

Objectives: The electrically evoked compound action potential (eCAP) is widely used in the clinic as an objective measure to assess cochlear implant functionality. During the past decade, there has been increasing interest in applying eCAPs for fitting of cochlear implants. Several studies have shown that eCAP-based fitting can potentially replace time-consuming behavioral fitting procedures, especially in young children.

A Novel Algorithm to Derive Spread of Excitation Based on Deconvolution.

Objective: The width of the spread of excitation (SOE) curve has been widely thought to represent an estimate of SOE. Therefore, correlates between psychophysical parameters, such as pitch discrimination and speech perception, and the width of SOE curves, have long been investigated. However, to date, no relationships between these objective and subjective measurements have yet been determined.