Correct placement of the electrode is crucial for cochlear implantation (CI) surgery. It determines the access to the auditory nerve and subsequent hearing performance. Here, we propose an objective measures tool that can partially verify the electrode position. The intracochlear spread of the electrical fields is measured and analyzed by means of multidimensional scaling resulting in an intuitive visual representation. The user can then detect major issues, such as electrode foldover or ossification. Other implantation issues, such as electrode migration into the scala vestibuli, may not significantly alter the electrical conduction pattern and remain undetected. Still, as the measurement is quick and readily available, it may be a valuable intraoperative verification tool.

Although the decision to implant should consider individual ear differences and other factors that might apply to a particular case, based on our data, all patients with preoperative scores of either 80% (phonemes correct) or 60% (words correct) and lower in an optimal-aided situation are potential candidates for a cochlear implant, provided that their preoperative speech perception score decreases below 50% (phonemes correct) or 20% (words correct), when background noise is added at a +5 dB signal to noise ratio.

The new test battery (or its reduced version), used as a measure of intelligibility, is a promising tool for guiding cochlear implant candidacy decisions and counseling for individual patients with prelingual deafness. Because intelligibility has superior predictive power in comparison to age at onset of deafness, the latter should be discarded as an exclusion criterion for cochlear implantation.

For prelingually deaf adults, intelligibility of the patient's speech-as represented by VOW-is a valid predictor of postimplant speech perception. A patient with a VOW score above a preset cutoff is much more likely to develop acceptable speech perception after implantation than a patient with a VOW score below that cutoff. The binary classification based on VOW and the associated probabilities of cochlear implant success in terms of speech perception can be used-in addition to existing criteria-to support the clinician in guiding patient expectations and in considering implant candidacy for individual patients.

CIS strategies tend to perform better than PPS strategies. PW, rate and paired stimulation have little effect on speech perception scores. However, they do have predictable and independent effects on both T and M levels for all strategies tested. The relationships found allow the improvement of the versatility of current fitting software and provide a basis to let the fitting software automatically adjust T and M levels if the PW or rate are adjusted in an existing program.