gms | German Medical Science

Cochlear company is currently developing a new cochlear implant system, the so-called system 4, otherwise known as RP8. It consists of a new implant, the CI24RE as well as a behind-the-ear speech processor the SP12, and a new software package called CustomSound for the fitting procedure and CustomSoundEP for electrophysiological measurement. In order to validate system 4, clinical studies are currently being undertaken in various clinical centers.

The current study presents the newly designed implementation of the Neural Response Telemetry (NRT) developed by Cochlear. Several improvements have been aimed at. Compared to the previous model, the newly designed implant is supposed to achieve an improved linearity of the amplifier at an improved signal-to-noise-ratio. The sample rate has been doubled to 20000 samples per second. A new automation algorithm has been designed in order to allow for completion of NRT measurement within shorter time and with much higher accuracy both on an intra-operative and post-operative level.

A sample of 9 patients had their NRT-thresholds measured postoperatively in 5 different places on the electrode array, both manually and via the automation tool. There is an average compliance between manual and automatical TNRT-values of up to 1% accuracy.

Time required for a TNRT-measurement via the 5 electrodes on the array is 7 minutes and therefore considerably reduced compared to software version 3.0. As the optimization measurements are no longer necessary or rather are being carried out automatically by the CustomSoundEP software, even less skilled staff will be in a position as to achieve highly accurate measurements.