Skip to main content

28.07.2017 | Research Article | Ausgabe 5/2017 Open Access

Journal of the Association for Research in Otolaryngology 5/2017

Spatial Selectivity in Cochlear Implants: Effects of Asymmetric Waveforms and Development of a Single-Point Measure

Journal of the Association for Research in Otolaryngology > Ausgabe 5/2017
Robert P. Carlyon, John M. Deeks, Jaime Undurraga, Olivier Macherey, Astrid van Wieringen


Three experiments studied the extent to which cochlear implant users’ spatial selectivity can be manipulated using asymmetric waveforms and tested an efficient method for comparing spatial selectivity produced by different stimuli. Experiment 1 measured forward-masked psychophysical tuning curves (PTCs) for a partial tripolar (pTP) probe. Maskers were presented on bipolar pairs separated by one unused electrode; waveforms were either symmetric biphasic (“SYM”) or pseudomonophasic with the short high-amplitude phase being either anodic (“PSA”) or cathodic (“PSC”) on the more apical electrode. For the SYM masker, several subjects showed PTCs consistent with a bimodal excitation pattern, with discrete excitation peaks on each electrode of the bipolar masker pair. Most subjects showed significant differences between the PSA and PSC maskers consistent with greater masking by the electrode where the high-amplitude phase was anodic, but the pattern differed markedly across subjects. Experiment 2 measured masked excitation patterns for a pTP probe and either a monopolar symmetric biphasic masker (“MP_SYM”) or pTP pseudomonophasic maskers where the short high-amplitude phase was either anodic (“TP_PSA”) or cathodic (“TP_PSC”) on the masker’s central electrode. Four of the five subjects showed significant differences between the masker types, but again the pattern varied markedly across subjects. Because the levels of the maskers were chosen to produce the same masking of a probe on the same channel as the masker, it was correctly predicted that maskers that produce broader masking patterns would sound louder. Experiment 3 exploited this finding by using a single-point measure of spread of excitation to reveal significantly better spatial selectivity for TP_PSA compared to TP_PSC maskers.

Unsere Produktempfehlungen

e.Med Interdisziplinär


Mit e.Med Interdisziplinär erhalten Sie Zugang zu allen CME-Fortbildungen und Fachzeitschriften auf Zusätzlich können Sie eine Zeitschrift Ihrer Wahl in gedruckter Form beziehen – ohne Aufpreis.

e.Med HNO


Mit e.Med HNO erhalten Sie Zugang zu CME-Fortbildungen des Fachgebietes HNO, den Premium-Inhalten der HNO-Fachzeitschriften, inklusive einer gedruckten HNO-Zeitschrift Ihrer Wahl.

Über diesen Artikel

Weitere Artikel der Ausgabe 5/2017

Journal of the Association for Research in Otolaryngology 5/2017 Zur Ausgabe

Neu im Fachgebiet HNO

Mail Icon II Newsletter

Bestellen Sie unseren kostenlosen Newsletter Update HNO und bleiben Sie gut informiert – ganz bequem per eMail.