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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

NRT Double Peaks revisited

Meeting Abstract

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  • corresponding author W. Lai - ENT Clinic, University Hospital, Zürich, Switzerland
  • N. Dillier - ENT Clinic, University Hospital, Zürich, 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. Doc05omci017

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

Published: May 31, 2005

© 2005 Lai 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.




The standard response waveform of evoked compound action potentials (ECAPs) recorded using Neural Response Telemetry (NRT) Recordings is characterized by a negative peak followed by a smaller positive peak. In a small but significant number of cases, however, the response waveform shows a double peak structure

Materials and Methods

One proposed model [1] attributes the two peaks to the presence of surviving dendritic structures. The origin of the two peaks has been questioned in that the double peak structure could be merely an artifact.


The new CIC4 research implant from Nucleus allows higher resolution recordings of the ECAP without having to resort to multiple data buffers, and also features several novel stimulus artifact cancellation/reduction techniques which do not depend on forward masking. Neural response recordings with double peaks have also been obtained with the CIC4 implant.


The implications of the results comparing the recordings with the current CIC3 (CI24M) implant and those with the CIC4 implant will be discussed.


Lai WK, Dillier N. A simple two-component model of the electrically evoked compound action potential in the human cochlea. Audiology & Neurootology, 2000; 5: 333-345.