gms | German Medical Science

Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants

Medical University of Hannover

01.06. bis 04.06.2005, Hannover

ECAP Measurements with the new Nucleus CI24RE Implant and the CustomSoundEP Software: Comparison of automatically and manually obtained results

Meeting Abstract

  • corresponding author L. Gärtner - Medizinische Hochschule Hannover
  • J. Pesch - Cochlear GmbH Hannover
  • A. Büchner - Medizinische Hochschule Hannover
  • R.D. Battmer - Medizinische Hochschule Hannover
  • T. Lenarz - Medizinische Hochschule Hannover

Medical University of Hannover, Department of Otolaryngology. Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants. Hannover, 01.-04.06.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05omci019

The electronic version of this article is the complete one and can be found online at:

Published: May 31, 2005

© 2005 Gärtner et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.




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 modular behind-the-ear speech processor the SP12, which can be used both as behind-the-ear and body-worn device, 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.

Materials and Methods

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. NRT thresholds (TNRT) can be estimated by the software in two different ways. First by emulating the audiologists procedure leading to a visual threshold, and second by extrapolation of the NRT response amplitude against stimulation level graph to find where the stimulation level axis was cut and hence the NRT amplitude was zero.


A sample of 10 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.