Comparing cochlear implant users' speech performance with processor fittings based on conventionally determined T and C levels or on compound action potential thresholds and live-voice speech in a prospective balanced crossover study.

OBJECTIVE

The objective of the present study is to improve the efficiency of the fitting procedure of cochlear implant processors by making use of measurements of the electrically evoked compound actio potential (ECAP) and live-voice speech.

DESIGN

In a randomised prospective cross-over design we compare speech performance of eighteen adult subjects when following the conventional fitting procedure to a procedure in which we use the profile of the ECAP threshold levels across the full electrode array measured intra-operatively. The overall level of the profile is shifted (by an equal amount of current units per electrode) until we find the threshold for live speech (new T levels) and the loudness comfort level (new C levels). Each fitting procedure is tested for 6 wk. Speech performance is measured in quiet and in noise every other week.

RESULTS

The results show little difference between the scores (Dutch CVC words) for the conventional fitting procedure and the ECAP based fitting, although the T and C levels may differ markedly.

CONCLUSION

The new fitting procedure is much faster and easier in the initial phase. Further improvement of performance may be obtained in a later stage of the fitting procedure by changing some individual electrodes on the basis of subjective responses.