ECAP Based CI-Fitting can be Easy. Final Report of a Multi-Center Study on Nucleus Fitting Software

Background

Fitting CI-processors is time-consuming and can be challenging for audiologists. Clinical fitting procedures are based on psychoacoustic and objective audiological measurements. But there is no generally accepted method.

Objective

Nucleus Fitting Software(NFS) was introduced to standardize the procedure and allow less experienced audiologists efficiently fit the CI-processor. The method is based on automatic recording of an ECAP threshold profile and behavioral estimates of loudness and sound. This study evaluated whether NFS provides CI-recipients with performances not inferior to clinically established fitting procedures.

Methods

This prospective, randomized, double-blind study was conducted at three experienced CI-centers. NFS modifications NFS-5, where 5 postoperatively measured ECAP thresholds(TNRT) are used to extrapolate the threshold-profile and NFS-22, where TNRTs of all electrodes are recorded, were compared with the clinical routine procedure. 48 newly unilaterally implanted, postlingually deafened adults were enrolled and distributed in six randomization groups. Seven evaluation sessions during 15 months allowed three months` familiarization with the various maps. Hearing performance was evaluated by subjective assessments(SSQ) and speech intelligibility in quiet(Freiburg monosyllabic words,OlSa) and in noise(OlSa).

Results

The speech intelligibility results showed a significant learning effect, whereas the results across the three adaptation methods were rather comparable. However, NFS-5 results were significantly worse in quiet and the main reasons for method related dropouts.

Conclusions

NFS-22 provides the majority of the participants with comparable hearing outcome to the clinically established fitting procedures. The development of an algorithm to identify patients, in which the use of the simplified fitting procedure is not effective, is still pending.