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Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants

Medical University of Hannover

01.06. bis 04.06.2005, Hannover

The Evolution of Neural Response Telemetry

Meeting Abstract

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  • corresponding author J.F. Patrick - Cochlear Ltd, Australia
  • 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. Doc05omci012

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

Published: May 31, 2005

© 2005 Patrick 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's NRT™ development arose from research conducted at the University of Iowa in 1990, when Brown and colleagues reported that they could record the neural activity resulting from intra-cochlear electrical stimulation using the percutaneous connector of Ineraid cochlear implant recipients.

Materials and Methods

This work suggested that the threshold neural response might be an objective measure that could assist with programming, and the design of Nucleus® Cochlear Implant (CI24M) was modified to include an NRT measurement capability. The data format of the CI24M radio frequency link is unique among commercial cochlear implant systems, in that the method used to transmit power and data to the implant allows for this transmission to be switched off for short periods, so that the very small neural response signals can be measured without interference from the high level RF link.


Following the introduction of the CI24M series implants in January 1997, the NRT software was developed in close collaboration with the ORL clinic of the University Hospital Zürich. Since 1999, the use of NRT has been explored extensively by clinics around the world. With the recently introduced CI24RE series implants the telemetry circuits have been further refined, increasing the probability of measuring a response and reducing the time it takes for measurement.


In Europe, research into NRT measurement techniques, response interpretation and use has been coordinated through annual NRT workshops, under the leadership of Norbert Dillier. The 11th NRT workshop in Geneva last year attracted more than 100 participants. Several clinical algorithms have been developed, to accelerate and simplify the fitting process, moving toward the goal to provide an initial MAP based on objective measures in only a few minutes.