scholarly journals Chronic Bilateral Cochlear Implant Stimulation in Early-Deaf Rabbits Restores Neural Binaural Sensitivity

2019 ◽  
Author(s):  
Woongsang Sunwoo ◽  
Bertrand Delgutte ◽  
Yoojin Chung
Keyword(s):  
Cochlear Implant ◽  
Sound Localization ◽  
Temporal Coding ◽  
Functional Restoration ◽  
Single Neurons ◽  
Chronic Stimulation ◽  
Interaural Time Differences ◽  
Speech Reception ◽  
Bilateral Cochlear Implant ◽  
Auditory Experience

AbstractCochlear implant (CI) users with a pre-lingual onset of hearing loss show poor sensitivity to interaural time differences (ITD), an important cue for sound localization and speech reception in noise. Similarly, neural ITD sensitivity in the inferior colliculus (IC) of neonatally-deafened animals is degraded compared to animals deafened as adults. Here, we show that chronic bilateral CI stimulation during development can partly reverse the effect of early-onset deafness on ITD sensitivity. The prevalence of ITD sensitive neurons was restored to the level of adult-deaf rabbits in the early-deaf rabbits that received chronic stimulation with wearable bilateral sound processors during development. In contrast, chronic CI stimulation did not improve temporal coding in early-deaf rabbits. The present study is the first report showing functional restoration of ITD sensitivity with CI stimulation in single neurons and highlights the importance of auditory experience during development.

scholarly journals Improving Localization and Speech Reception in Noise for Bilateral Cochlear Implant Recipients

2019 ◽  
Vol 23 ◽  
pp. 233121651983149 ◽  
Author(s):  
Wendy B. Potts ◽  
Lakshmish Ramanna ◽  
Trevor Perry ◽  
Christopher J. Long
Keyword(s):  
Cochlear Implant ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Interaural Level Difference ◽  
Mean Square ◽  
Localization Accuracy ◽  
Speech In Noise ◽  
Speech Reception ◽  
Bilateral Cochlear Implant ◽  
Comparative Survey

This study looked at different methods to preserve interaural level difference (ILD) cues for bilateral cochlear implant (BiCI) recipients. One possible distortion to ILD is from automatic gain control (AGC). Localization accuracy of BiCI recipients using default versus increased AGC threshold and linked AGCs versus independent AGCs was examined. In addition, speech reception in noise was assessed using linked versus independent AGCs and enabling and disabling Autosensitivity™ Control. Subjective information via a diary and questionnaire was also collected about maps with linked and independent AGCs during a take-home experience. Localization accuracy improved in the increased AGC threshold and the linked AGCs conditions. Increasing the AGC threshold resulted in a 4° improvement in root mean square error averaged across all speaker locations. Using linked AGCs, BiCI participants experienced an 8° improvement for all speaker locations and a 19° improvement at the speaker location most affected by the AGC. Speech reception threshold in noise improved by an average of 2.5 dB when using linked AGCs versus independent AGCs. In addition, the effect of linked AGCs on speech in noise was compared with that of Autosensitivity™ Control. The Speech, Spatial, and Qualities of Hearing Scale-12 question comparative survey showed an improvement when using maps with linked AGCs. These findings support the hypothesis that ILD cues may be preserved by increasing the AGC threshold or linking AGCs.

scholarly journals Reducing the Device Delay Mismatch Can Improve Sound Localization in Bimodal Cochlear Implant/Hearing-Aid Users

2019 ◽  
Vol 23 ◽  
pp. 233121651984387 ◽  
Author(s):  
Stefan Zirn ◽  
Julian Angermeier ◽  
Susan Arndt ◽  
Antje Aschendorff ◽  
Thomas Wesarg
Keyword(s):  
Cochlear Implant ◽  
Sound Localization ◽  
Delay Line ◽  
Hearing Aid ◽  
Interaural Time Differences ◽  
Localization Accuracy ◽  
Everyday Situation ◽  
Acclimatization Period ◽  
Study Participants ◽  
Line P

In users of a cochlear implant (CI) together with a contralateral hearing aid (HA), so-called bimodal listeners, differences in processing latencies between digital HA and CI up to 9 ms constantly superimpose interaural time differences. In the present study, the effect of this device delay mismatch on sound localization accuracy was investigated. For this purpose, localization accuracy in the frontal horizontal plane was measured with the original and minimized device delay mismatch. The reduction was achieved by delaying the CI stimulation according to the delay of the individually worn HA. For this, a portable, programmable, battery-powered delay line based on a ring buffer running on a microcontroller was designed and assembled. After an acclimatization period to the delayed CI stimulation of 1 hr, the nine bimodal study participants showed a highly significant improvement in localization accuracy of 11.6% compared with the everyday situation without the delay line ( p < .01). Concluding, delaying CI stimulation to minimize the device delay mismatch seems to be a promising method to increase sound localization accuracy in bimodal listeners.

A SPIKE-BASED MODEL OF BINAURAL SOUND LOCALIZATION

1999 ◽  
Vol 09 (05) ◽  
pp. 447-452 ◽  
Author(s):  
CARSTEN SCHAUER ◽  
PETER PASCHKE
Keyword(s):  
Sound Localization ◽  
Hardware Implementation ◽  
Temporal Coding ◽  
Practical Application ◽  
Spike Response ◽  
Interaural Time Differences ◽  
Audio Data ◽  
Spike Response Model ◽  
Winner Take All ◽  
Binaural Sound

This paper describes a spike-based model of binaural sound localization using interaural time differences (ITDs). To handle the problem of temporal coding and to facilitate a hardware implementation all neurons are simulated by a spike response model, which includes postsynaptic potentials (PSPs) and a refractory period. A winner-take-all (WTA) network selects the dominant source from the representation of the sound's angles of incidences, and can be biased by a multisensory support, We use simulations on real audio data to investigate the function and the practical application of the system.

scholarly journals Pinna-Imitating Microphone Directionality Improves Sound Localization and Discrimination in Bilateral Cochlear Implant Users

2020 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Tim Fischer ◽  
Christoph Schmid ◽  
Martin Kompis ◽  
Georgios Mantokoudis ◽  
Marco Caversaccio ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Sound Localization ◽  
Bilateral Cochlear Implant

scholarly journals Reweighting of Binaural Localization Cues in Bilateral Cochlear-Implant Listeners

2021 ◽  
Author(s):  
Maike Klingel ◽  
Bernhard Laback
Keyword(s):  
Cochlear Implant ◽  
Sound Localization ◽  
Visual Information ◽  
Electrode Pair ◽  
Optimal Conditions ◽  
Visual Reinforcement ◽  
Pulse Trains ◽  
Before And After ◽  
Bilateral Cochlear Implant ◽  
Binaural Localization

AbstractNormal-hearing (NH) listeners rely on two binaural cues, the interaural time (ITD) and level difference (ILD), for azimuthal sound localization. Cochlear-implant (CI) listeners, however, rely almost entirely on ILDs. One reason is that present-day clinical CI stimulation strategies do not convey salient ITD cues. But even when presenting ITDs under optimal conditions using a research interface, ITD sensitivity is lower in CI compared to NH listeners. Since it has recently been shown that NH listeners change their ITD/ILD weighting when only one of the cues is consistent with visual information, such reweighting might add to CI listeners’ low perceptual contribution of ITDs, given their daily exposure to reliable ILDs but unreliable ITDs. Six bilateral CI listeners completed a multi-day lateralization training visually reinforcing ITDs, flanked by a pre- and post-measurement of ITD/ILD weights without visual reinforcement. Using direct electric stimulation, we presented 100- and 300-pps pulse trains at a single interaurally place-matched electrode pair, conveying ITDs and ILDs in various spatially consistent and inconsistent combinations. The listeners’ task was to lateralize the stimuli in a virtual environment. Additionally, ITD and ILD thresholds were measured before and after training. For 100-pps stimuli, the lateralization training increased the contribution of ITDs slightly, but significantly. Thresholds were neither affected by the training nor correlated with weights. For 300-pps stimuli, ITD weights were lower and ITD thresholds larger, but there was no effect of training. On average across test sessions, adding azimuth-dependent ITDs to stimuli containing ILDs increased the extent of lateralization for both 100- and 300-pps stimuli. The results suggest that low-rate ITD cues, robustly encoded with future CI systems, may be better exploitable for sound localization after increasing their perceptual weight via training.

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