Table 1: Width at half maximum for average NRT tuning curves. The widths were obtained by fitting Gaussian curves to the tuning curves. For electrodes 1 and 20 the half-width-at-half-maximum is indicated. For electrodes 6, 11 and 16, full-width-at-half-maximum is indicated. Widths are indicated in number of electrode distances. The reduction of width due to modiolus hugging was significant for electrodes 1, 6 and 20 Electrode numberTuning width before Tuning width after (base to apex) modiolus hugging modiolus hugging 18 .9 (± 0.6) 6.2 (± 0.6) 61 0.9 (± 0.3) 9.4 (± 0.3) 11 12.3 (± 0.6) 11.2 (± 0.8) 1613.4 (± 0.5) 12.8 (± 0.6) 20 8.5 (± 0.3) 6.6 (± 0.4) Discussion and conclusionModiolus hugging gave a small but significant reduction of spread of neural excitation on the basal and apical apart of the Nucleus CI24R(CS) cochlear implant. There was no significant effect on the mid-section of the implant array. To our knowledge, our results are the first within-subject demonstration of the effect of modiolus hugging. Our intra-operative measurements had to be performed at a high stimulus level. At lower stimulation levels, closer to those an implant user would typically use, the reduction of the spread of excitation may be more pronounced, as is also suggested by Cohen et al. (2003). We conclude that modiolus hugging improves stimulation selectivity. This may improve speech discrimination and be beneficial for implant users.

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