Enhancement of interaural level differences for bilateral cochlear implant users

Gajęcki, Tom; Nogueira, Waldo

doi:10.1016/j.heares.2021.108313

Cited by 4 publications

(2 citation statements)

References 60 publications

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“…One recent study explored the enhancement of ILDs using an artificial current-versus-angle function to modify the levels delivered by the contralateral CI's basal electrodes. This resulted in improvements in sound source discrimination on the frontal horizontal plane for some BiCI users [43].…”

Section: Discussionmentioning

confidence: 99%

A Mixed-Rate Strategy on a Bilaterally-Synchronized Cochlear Implant Processor Offering the Opportunity to Provide Both Speech Understanding and Interaural Time Difference Cues

Dennison,

Thakkar,

Kan

et al. 2024

JCM

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Background/Objective: Bilaterally implanted cochlear implant (CI) users do not consistently have access to interaural time differences (ITDs). ITDs are crucial for restoring the ability to localize sounds and understand speech in noisy environments. Lack of access to ITDs is partly due to lack of communication between clinical processors across the ears and partly because processors must use relatively high rates of stimulation to encode envelope information. Speech understanding is best at higher stimulation rates, but sensitivity to ITDs in the timing of pulses is best at low stimulation rates. Methods: We implemented a practical “mixed rate” strategy that encodes ITD information using a low stimulation rate on some channels and speech information using high rates on the remaining channels. The strategy was tested using a bilaterally synchronized research processor, the CCi-MOBILE. Nine bilaterally implanted CI users were tested on speech understanding and were asked to judge the location of a sound based on ITDs encoded using this strategy. Results: Performance was similar in both tasks between the control strategy and the new strategy. Conclusions: We discuss the benefits and drawbacks of the sound coding strategy and provide guidelines for utilizing synchronized processors for developing strategies.

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Section: Discussionmentioning

confidence: 99%

A Mixed-Rate Strategy on a Bilaterally-Synchronized Cochlear Implant Processor Offering the Opportunity to Provide Both Speech Understanding and Interaural Time Difference Cues

Dennison,

Thakkar,

Kan

et al. 2024

JCM

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“…As a result, many HAD users have limited spatial hearing capabilities (Dorman et al, 2016;Fletcher et al, 2020a;Pastore et al, 2021). While there is a growing interest in approaches for improving spatial hearing in hearing-impaired listeners (e.g., Moore et al, 2016;Williges et al, 2018;Fletcher and Zgheib, 2020;Fletcher et al, 2020a,b;Gajecki and Nogueira, 2021), clinical testing of spatial hearing ability remains limited.…”

Section: Introductionmentioning

confidence: 99%

A Compact Two-Loudspeaker Virtual Sound Reproduction System for Clinical Testing of Spatial Hearing With Hearing-Assistive Devices

Hamdan

Fletcher

2022

Front. Neurosci.

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Exciting developments in hearing aid and cochlear implant technology for linking signal processing across the ears have improved spatial hearing outcomes. This has resulted in an increased emphasis on clinical assessment of the spatial hearing abilities of hearing-assistive device users. Effective assessment of spatial hearing currently requires a large and costly loudspeaker array system, housed in a heavily acoustically treated testing room. This imposes economic and logistical constraints that limit proliferation of array systems, particularly in developing nations. Despite their size and cost, the ability of current clinical array systems to reproduce realistic spatial sound fields is limited, which substantially reduces the range of realistic acoustic scenes that can be used for diagnostic testing. We propose an alternative low-cost, compact virtual acoustics system with just two loudspeakers. This system uses crosstalk cancelation to reproduce pressure signals at the device microphones that match those for real-world sound sources. Furthermore, in contrast to clinical array systems, the system can adapt to different room acoustics, removing the requirement for a heavily acoustically treated testing environment. We conducted a proof-of-concept study in two stages: in the first, we evaluated the physical performance of the system for a stationary listener in anechoic conditions and in a small audiological testing booth with moderate acoustic treatment. To do this, a head and torso simulator was fitted with specially adapted hearing-assistive devices that allowed direct access to the microphone signals. These microphone signals were compared for real and virtual sound sources at numerous source locations. In the second stage, we quantified the system’s robustness to head rotations with and without the system adapting for head position. In the stationary case, the system was found to be highly effective at reproducing signals, such as speech, at all tested source locations. When head rotation was added, it performed well for rotations of up to 2°, even without adapting. However, performance improved markedly for larger rotations when the system adapted. These findings suggest that a compact, low-cost virtual acoustics system can give wider access to advanced and ecologically valid audiological testing, which could substantially improve clinical assessment of hearing-assistive device users.

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Impact of processing-latency induced interaural delay and level discrepancy on sensitivity to interaural level differences in cochlear implant users

Körtje

Stöver

Baumann

et al. 2023

Eur Arch Otorhinolaryngol

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Purpose This study investigated whether an interaural delay, e.g. caused by the processing latency of a hearing device, can affect sensitivity to interaural level differences (ILDs) in normal hearing subjects or cochlear implant (CI) users with contralateral normal hearing (SSD-CI). Methods Sensitivity to ILD was measured in 10 SSD-CI subjects and in 24 normal hearing subjects. The stimulus was a noise burst presented via headphones and via a direct cable connection (CI). ILD sensitivity was measured for different interaural delays in the range induced by hearing devices. ILD sensitivity was correlated with results obtained in a sound localization task using seven loudspeakers in the frontal horizontal plane. Results In the normal hearing subjects the sensitivity to interaural level differences deteriorated significantly with increasing interaural delays. In the CI group, no significant effect of interaural delays on ILD sensitivity was found. The NH subjects were significantly more sensitive to ILDs. The mean localization error in the CI group was 10.8° higher than in the normal hearing group. No correlation between sound localization ability and ILD sensitivity was found. Conclusion Interaural delays influence the perception of ILDs. For normal hearing subjects a significant decrement in sensitivity to ILD was measured. The effect could not be confirmed in the tested SSD-CI group, probably due to a small subject group with large variations. The temporal matching of the two sides may be beneficial for ILD processing and thus sound localization for CI patients. However, further studies are needed for verification.

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Enhancement of interaural level differences for bilateral cochlear implant users

Cited by 4 publications

References 60 publications

A Mixed-Rate Strategy on a Bilaterally-Synchronized Cochlear Implant Processor Offering the Opportunity to Provide Both Speech Understanding and Interaural Time Difference Cues

A Mixed-Rate Strategy on a Bilaterally-Synchronized Cochlear Implant Processor Offering the Opportunity to Provide Both Speech Understanding and Interaural Time Difference Cues

A Compact Two-Loudspeaker Virtual Sound Reproduction System for Clinical Testing of Spatial Hearing With Hearing-Assistive Devices

Impact of processing-latency induced interaural delay and level discrepancy on sensitivity to interaural level differences in cochlear implant users

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