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

Enhanced NRT research using the Nucleus® Electro-Physiology Software: CustomSound-EP™

Meeting Abstract

  • corresponding author M. Killian - Cochlear Technology Center, Belgium
  • D. Cafarelli Dees - Cochlear Europe Ltd, UK
  • E. von Wallenberg - Cochlear AG, Switzerland

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. Doc05omci013

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

Published: May 31, 2005

© 2005 Killian 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.




Interest in electrophysiological measurements and in particular the electrically evoked compound action potential (ECAP) has increased since 1997 with the ease of recording introduced by the Nucleus® Neural Response Telemetry (NRT™) within CI24 CI system. Cochlear recently released the Nucleus Freedom™ System with the Nucleus Freedom Cochlear Implant (CI24RE). The CI24RE contains an improved NRT™ amplifier with fine gain adjustments (range 40dB - 70dB), a low noise floor of 1μV rms at default gain of 60dB, an increased sampling rate of 20k samples/second and an up to 64 samples/recording. This new amplifier coupled with the new NRT/electro-physiology software allows for faster and more accurate NRT recordings.

Materials and Methods

CustomSound EP software is part of the CustomSound Suite and is designed to perform basic and advanced electrophysiology research to guide clinical fitting, diagnosis and monitoring using a common database and software environment. New artifact cancellation methods have been implemented as well as AutoNRT™, a fully automated algorithm.


AutoNRT™ facilitates measurement of T-NRT profiles to streamline objective fitting methods. Furthermore, a user-friendly and flexible environment is available for advanced NRT research on Amplitude Growth Functions, Recovery Functions, Spread Of Excitation and Rate Adaptation. NRT analysis can be customized and multiple graph panes are available for on-line monitoring.


CustomSound EP also facilitates triggering of external equipment to perform other electrophysiological measurements such as Electrically evoked Auditory Brainstem Responses (EABR), Electrically Stapedius Reflexes (ESRT) and Cortically Evoked Potentials(CEP). Measurement history and threshold profiles of these measurements can be stored in the custom database and used to streamline objective fitting methods. Examples of clinical applications and enhanced research possibilities will be discussed.