Clinical Research Studies

Two unique attributes of the Med-El cochlear implant system are a long electrode array allowing for apical stimulation of the cochlea and a speech processing strategy (FSP) which specifically provides fine temporal cues in the apex. The deep insertion of the Med-El array allows for encoding place pitch for a greater cochlear extent than the Nucleus and Advanced Bionics arrays. Additionally, the deep insertion allows for temporal encoding in apex where presumably temporal resolution is greatest. However, despite the advantages of the deeply inserted electrode array and the FSP speech processing strategy, there has been little evidence that apical stimulation has provided a consistent clinical benefit (e.g. Magnusson, 2011; Lorens et al., 2010; Riss et al., 2009; Riss et al., 2008). One potential limitation in clinical performance could come from individual variability in both spectral and temporal sensitivities in the apex such that some (but not all) patients benefit greatly from apical stimulation resulting in unimpressive improvements averaged across all subjects while truthfully some patients are receiving large benefits. Another potential limitation in performance could be a non-optimal implementation of temporal coding in FSP. In the following proposal, we will psychophysically explore the temporal and spectral parameter space in the apex to gain an understanding of the potential capabilities and limitations of apical stimulation. Additionally, we will correlate performance on our psychophysical tasks with performance on a speech in noise task and musical pitch task to determine how temporal and spectral cues relate to clinical performance. A correlation between either temporal or spectral resolution in the apex and clinical performance could be used to both guide future refinements of speech processing strategies as well as clinically predict who would benefit from specific processing strategies.