Effect of current level on electrode discrimination in electrical stimulation

• Published in: Hearing research Vol. 136; no. 1; pp. 159 - 164
• Main Authors: McKay, Colette M, O’Brien, Anna, James, Chris J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.1999; Elsevier
• Subjects: Analysis of Variance; Biological and medical sciences; Choice Behavior; Cochlear implant; Cochlear Implants; Current level; Discrimination (Psychology); Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology; Electric Stimulation; Electrical stimulation; Electricity; Electrode discrimination; Electrodes; Humans; Medical sciences; Non tumoral diseases; Otorhinolaryngology. Stomatology; Cochlear implant; Electrical stimulation; Current level; Electrode discrimination; Electrodes; Human; Implant; Internal ear disease; Electrical stimulus; Auditory disorder; Cochlea; Instrumentation therapy; ENT disease; Stimulus intensity; Discrimination task; Hearing loss
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/S0378-5955(99)00121-5

The effect of the stimulation intensity (current amplitude) on the ability to discriminate electrodes was tested in an experiment with four adult users of the Nucleus-22 cochlear implant. A total of 12 adjacent pairs of electrodes were used in the four-interval forced-choice discrimination task with random current variation. Tests were carried out at three average stimulation levels: 40 and 70% of the dynamic range and close to maximum comfortable loudness. Analysis of variance revealed a significant ( P<0.0001) deterioration in electrode discrimination with a decreasing level. However, the overall effect was very small, representing a deterioration in the discrimination score of only 18% correct from the highest to lowest levels tested. The reason for the small deterioration in discriminability with a decreasing level is difficult to determine from this experiment, however, the results are consistent with the hypothesis that changes in the ‘peak’ or ‘edge’ of the excitation pattern are more important for discrimination tasks than the relative amount of non-overlap of the excitation areas from the two electrodes.