scholarly journals Effect of chronic stimulation and stimulus level on temporal processing by cochlear implant listeners

2018 ◽  
Author(s):  
Robert P. Carlyon ◽  
François Guérit ◽  
Alexander J. Billig ◽  
Yu Chuen Tam ◽  
Frances Harris ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Temporal Processing ◽  
Dynamic Range ◽  
Stimulus Level ◽  
Adaptive Procedure ◽  
Direct Stimulation ◽  
Upper Limit ◽  
Upper Limits ◽  
Series Of Experiments ◽  
Rate Discrimination

AbstractA series of experiments investigated potential changes in temporal processing during the months following activation of a cochlear implant (CI) and as a function of stimulus level. Experiment 1 tested patients on the day of implant activation and two and six months later. All stimuli were presented using direct stimulation of a single apical electrode. The dependent variables were rate discrimination ratios (RDRs) for pulse trains with rates centred on 120 pulses per second (pps), obtained using an adaptive procedure, and a measure of the upper limit of temporal pitch, obtained using a pitch-ranking procedure.All stimuli were presented at their most comfortable level (MCL). RDRs decreased from 1.23 to 1.16 and the upper limit increased from 357 to 485 pps from 0 to 2 months post-activation, with no overall change from 2 to 6 months. Because MCLs and hence the testing level increased across sessions, two further experiments investigated whether the performance changes observed across sessions could be due to level differences. Experiment 2 re-tested a subset of subjects at 9 months post-activation, using current levels similar to those used at 0 months. Although the stimuli sounded softer, some subjects showed lower RDRs and/or higher upper limits at this re-test. Experiment 3 measured RDRs and the upper limit for a separate group of subjects at levels equal to 60%, 80%, and 100% of the dynamic range. RDRs decreased with increasing level. The upper limit increased with increasing level for most subjects, with two notable exceptions. Implications of the results for temporal plasticity are discussed, along with possible influences of the effects of level and of across-session learning.

scholarly journals Effect of Chronic Stimulation and Stimulus Level on Temporal Processing by Cochlear Implant Listeners

2018 ◽  
Vol 20 (2) ◽  
pp. 169-185 ◽  
Author(s):  
Robert P. Carlyon ◽  
François Guérit ◽  
Alexander J. Billig ◽  
Yu Chuen Tam ◽  
Frances Harris ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Temporal Processing ◽  
Stimulus Level ◽  
Chronic Stimulation

scholarly journals Amplitude Growth Functions of Auditory Nerve Responses to Electric Pulse Stimulation With Varied Interphase Gaps in Cochlear Implant Users With Ipsilateral Residual Hearing

2021 ◽  
Vol 25 ◽  
pp. 233121652110141
Author(s):  
Marina Imsiecke ◽  
Andreas Büchner ◽  
Thomas Lenarz ◽  
Waldo Nogueira
Keyword(s):  
Cochlear Implant ◽  
Dynamic Range ◽  
Electric Pulse ◽  
Objective Measure ◽  
Stimulus Level ◽  
Control Group ◽  
Electrode Impedance ◽  
Residual Hearing ◽  
Growth Functions ◽  
Amplitude Growth

Amplitude growth functions (AGFs) of electrically evoked compound action potentials (eCAPs) with varying interphase gaps (IPGs) were measured in cochlear implant users with ipsilateral residual hearing (electric-acoustic stimulation [EAS]). It was hypothesized that IPG effects on AGFs provide an objective measure to estimate neural health. This hypothesis was tested in EAS users, as residual low-frequency hearing might imply survival of hair cells and hence better neural health in apical compared to basal cochlear regions. A total of 16 MED-EL EAS subjects participated, as well as a control group of 16 deaf cochlear implant users. The IPG effect on the AGF characteristics of slope, threshold, dynamic range, and stimulus level at 50% maximum eCAP amplitude (level50%) was investigated. AGF threshold and level50% were significantly affected by the IPG in both EAS and control group. The magnitude of AGF characteristics correlated with electrode impedance and electrode-modiolus distance (EMD) in both groups. In contrast, the change of the AGF characteristics with increasing IPG was independent of these electrode-specific measures. The IPG effect on the AGF level50% in both groups, as well as on the threshold in EAS users, correlated with the duration of hearing loss, which is a predictor of neural health. In EAS users, a significantly different IPG effect on level50% was found between apical and medial electrodes. This outcome is consistent with our hypothesis that the influence of IPG effects on AGF characteristics provides a sensitive measurement and may indicate better neural health in the apex compared to the medial cochlear region in EAS users.

scholarly journals A Comparison of Place-Pitch-Based Interaural Electrode Matching Methods for Bilateral Cochlear-Implant Users

2021 ◽  
Vol 25 ◽  
pp. 233121652199732
Author(s):  
Kenneth K. Jensen ◽  
Stefano Cosentino ◽  
Joshua G. W. Bernstein ◽  
Olga A. Stakhovskaya ◽  
Matthew J. Goupell
Keyword(s):  
Cochlear Implant ◽  
Reference Electrode ◽  
Test Methods ◽  
Adaptive Procedure ◽  
Response Distribution ◽  
Direct Stimulation ◽  
Starting Point ◽  
Bilateral Cochlear Implant ◽  
Apical Half ◽  
Optimal Approach

Interaural place-of-stimulation mismatch for bilateral cochlear-implant (BI-CI) listeners is often evaluated using pitch-comparison tasks that can be susceptible to procedural biases. Bias effects were compared for three sequential interaural pitch-comparison tasks in six BI-CI listeners using single-electrode direct stimulation. The reference (right ear) was a single basal, middle, or apical electrode. The comparison electrode (left ear) was chosen from one of three ranges: basal half, full array, or apical half. In Experiment 1 (discrimination), interaural pairs were chosen randomly (method of constant stimuli). In Experiment 2 (ranking), an efficient adaptive procedure rank ordered 3 reference and 6 or 11 comparison electrodes. In Experiment 3 (matching), listeners adjusted the comparison electrode to pitch match the reference. Each experiment was evaluated for testing-range bias (point of subjective equality [PSE] vs. comparison-range midpoint) and reference-electrode slope bias (PSE vs. reference electrode). Discrimination showed large biases for both metrics; matching showed a smaller but significant reference-electrode bias; ranking showed no significant biases in either dimension. Ranking and matching were also evaluated for starting-point bias (PSE vs. adaptive-track starting point), but neither showed significant effects. A response-distribution truncation model explained a nonsignificant bias for ranking but it could not fully explain the observed biases for discrimination or matching. It is concluded that (a) BI-CI interaural pitch comparisons are inconsistent across test methods; (b) biases must be evaluated in more than one dimension before accepting the results as valid; and (c) of the three methods tested, ranking was least susceptible to biases and therefore emerged as the optimal approach.

scholarly journals Perceptual learning of pitch provided by cochlear implant stimulation rate

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0242842
Author(s):  
Susan R. S. Bissmeyer ◽  
Shaikat Hossain ◽  
Raymond L. Goldsworthy
Keyword(s):  
Individual Differences ◽  
Cochlear Implant ◽  
Perceptual Learning ◽  
Predictive Power ◽  
Temporal Integration ◽  
Stimulation Rate ◽  
Upper Limit ◽  
Spatial Tuning ◽  
Consistent Manner ◽  
Rate Discrimination

Cochlear implant users hear pitch evoked by stimulation rate, but discrimination diminishes for rates above 300 Hz. This upper limit on rate pitch is surprising given the remarkable and specialized ability of the auditory nerve to respond synchronously to stimulation rates at least as high as 3 kHz and arguably as high as 10 kHz. Sensitivity to stimulation rate as a pitch cue varies widely across cochlear implant users and can be improved with training. The present study examines individual differences and perceptual learning of stimulation rate as a cue for pitch ranking. Adult cochlear implant users participated in electrode psychophysics that involved testing once per week for three weeks. Stimulation pulse rate discrimination was measured in bipolar and monopolar configurations for apical and basal electrodes. Base stimulation rates between 100 and 800 Hz were examined. Individual differences were quantified using psychophysically derived metrics of spatial tuning and temporal integration. This study examined distribution of measures across subjects, predictive power of psychophysically derived metrics of spatial tuning and temporal integration, and the effect of training on rate discrimination thresholds. Psychophysical metrics of spatial tuning and temporal integration were not predictive of stimulation rate discrimination, but discrimination thresholds improved at lower frequencies with training. Since most clinical devices do not use variable stimulation rates, it is unknown to what extent recipients may learn to use stimulation rate cues if provided in a clear and consistent manner.

Auditory Cortical Images of Cochlear-Implant Stimuli: Dependence on Electrode Configuration

2002 ◽  
Vol 87 (1) ◽  
pp. 478-492 ◽  
Author(s):  
Julie Arenberg Bierer ◽  
John C. Middlebrooks
Keyword(s):  
Cochlear Implant ◽  
Guinea Pigs ◽  
Common Ground ◽  
Dynamic Range ◽  
Primary Auditory Cortex ◽  
Stimulus Level ◽  
Electrode Configuration ◽  
Spatiotemporal Pattern ◽  
Active Electrode ◽  
Sensitive Site

This study examines patterns of auditory cortical activity elicited by single-pulse cochlear implant stimuli that vary in electrode configuration, cochlear place of stimulation, and stimulus level. Recordings were made from the primary auditory cortex (area A1) of ketamine-anesthetized guinea pigs. The spatiotemporal pattern of neural spike activity was measured simultaneously across 16 cortical locations spanning approximately 2–3 octaves of the tonotopic axis. Such a pattern, averaged over 40 presentations of any particular stimulus, was defined as the “cortical image” of that stimulus. Acutely deafened guinea pigs were implanted with a 6-electrode animal version of the 22-electrode Nucleus banded electrode array (Cochlear). Cochlear electrode configurations consisted of monopolar (MP), bipolar (BP + N) with N inactive electrodes between the active and return electrodes (0 ≤ N ≤ 4), tripolar (TP) with one active electrode and two flanking return electrodes, and common ground (CG) with one active electrode and as many as five return electrodes. Cortical images typically showed a focus of maximum spike probability and minimum latency. Spike probabilities tended to decrease, and latencies tended to increase, with increasing cortical distance from that focus. Cortical images of TP stimuli were the most spatially compact, followed by BP + N images, and then MP images, which were the broadest. Images of CG stimuli were rather variable across animals and stimulus channels. The locations of cortical images shifted systematically from caudal to rostral as the cochlear place of stimulation changed from basal to apical. At the most sensitive cortical site for each condition, the dynamic ranges over which spike rates increased with increased current level were restricted to about 1–2 dB, regardless of configuration. Dynamic ranges tended to increase with increasing cortical distance from the most sensitive site. Electrode configurations that produced compact cortical images (e.g., TP and BP + 0) showed the greatest range of thresholds within each cortical image and the largest dynamic range at cortical sites removed from the most sensitive site.

Estimates of Loudness, Loudness Discomfort, and the Auditory Dynamic Range: Normative Estimates, Comparison of Procedures, and Test-Retest Reliability

2005 ◽  
Vol 16 (02) ◽  
pp. 085-100 ◽  
Author(s):  
LaGuinn P. Sherlock ◽  
Craig Formby
Keyword(s):  
Reference Values ◽  
Dynamic Range ◽  
Test Methods ◽  
Intersubject Variability ◽  
Retest Reliability ◽  
Growth Functions ◽  
Upper Limit ◽  
Series Of Experiments ◽  
Test Retest Reliability ◽  
Loudness Growth

The purpose of this series of experiments was to establish normative reference values for absolute and relative judgements of loudness discomfort and for the auditory dynamic range (DR), and to evaluate intersubject variability and intrasubject test-retest reliability for the respective measures of loudness discomfort. To establish the normal auditory DR, audiometric thresholds and loudness discomfort levels (LDLs) were measured from a group of 59 normal-hearing adults without sound tolerance problems. The resulting estimates of the LDL and DR were on the order of 100 dB HL and 95 dB, respectively. A subset (n = 18) of this larger group participated in further studies in which loudness growth functions and the upper limit of the auditory DR were measured by categorical scaling judgments. The findings revealed no significant differences between the test methods for absolute (LDL) and relative (categorical scaling) judgements of loudness discomfort, intersubject variability, or intrasubject test-retest reliability, and suggest that the simple LDL estimate of loudness discomfort is an efficient and valid clinical measure for characterizing the "threshold of discomfort."

Vitamin-A-Exzess durch Pferdefleischprodukte mit hohen Leberanteilen

2013 ◽  
Vol 41 (01) ◽  
pp. 31-36
Author(s):  
E. Kienzle ◽  
N. Becker
Keyword(s):  
Vitamin A ◽  
Eine Analyse ◽  
Upper Limit ◽  
Upper Limits

ZusammenfassungIm Rahmen einer Eliminationsdiät wird regelmäßig Pferdefleisch eingesetzt. Aus Gründen der Praktikabilität verwenden Tierbesitzer häufig kommerziell erhältliches Pferdefleisch aus der Dose. Aufgrund eines Berichts von Zervikalspondylosen bei einer auf Futtermittel allergischen Katze erfolgte eine Analyse verschiedener auf Pferdefleisch basierender Produkte hinsichtlich des Vitamin-AGehalts.In 14 Pferdefleischerzeugnissen wurde der Vitamin-A-Gehalt (Retinol) analysiert. Der Gehalt an umsetzbarer Energie wurde mithilfe von Schätzformeln auf Basis der Deklaration berechnet.In Produkten mit deklarierten Anteilen von Leber, Innereien oder tierischen Nebenprodukten konnten zum Teil erhebliche Vitamin-A-Gehalte festgestellt werden. Bei alleiniger Verfütterung eines dieser Produkte (Deckung des durchschnittlichen Energiebedarfs) würde die Vitamin-A-Versorgung nur knapp unter dem Safe Upper Limit der Katze sowie oberhalb des Safe Upper Limits beim Hund liegen.Bei All-Meat-Produkten sollte nicht nur die Deklaration, sondern auch der Inhalt näher betrachtet werden, um einen Hinweis auf eventuell hohe Leberanteile zu erhalten.Aufgrund der Ergebnisse ist eine exzessive Vitamin-A-Aufnahme bei langfristiger Verfütterung von Pferdefleischprodukten mit hohen Leberanteilen nicht auszuschließen.

Effect of different input dynamic range variables on cochlear implant performance in postlingual cochlear implant in adults

2019 ◽  
Vol 69 (3) ◽  
Author(s):  
Tarek A. Ghannoum ◽  
Mona H. Selim ◽  
Amira M. El-Shennawy ◽  
Zahraa M. Elbohy
Keyword(s):  
Cochlear Implant ◽  
Dynamic Range

scholarly journals Search for π0 decays to invisible particles

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
E. Cortina Gil ◽  
◽  
A. Kleimenova ◽  
E. Minucci ◽  
S. Padolski ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Ratio ◽  
Standard Model Higgs Boson ◽  
Scalar Mixing ◽  
Upper Limit ◽  
Upper Limits ◽  
The Standard Model ◽  
Model Independent

Abstract The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.

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