Binaural unmasking with temporal envelope and fine structure in listeners with cochlear implants

Todd, Ann E.; Goupell, Matthew J.; Litovsky, Ruth Y.

doi:10.1121/1.5102158

Cited by 8 publications

(7 citation statements)

References 44 publications

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“…Previously performed experiments which investigated the perception of dynamic ITDs used single-electrode stimulation and different signal durations and are therefore not directly comparable to the results obtained in this study (Todd et al, 2019;van Hoesel, 2007;Zirn et al, 2016). While single-electrode experiments are meaningful to probe physiological limits, we aimed to provide data under more life-like test conditions.…”

Section: A Headphone-based Experimentsmentioning

confidence: 75%

Effects of temporal fine structure preservation on spatial hearing in bilateral cochlear implant users

Fischer

Schmid

Kompis

et al. 2021

The Journal of the Acoustical Society of America

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Typically, the coding strategies of cochlear implant audio processors discard acoustic temporal fine structure information (TFS), which may be related to the poor perception of interaural time differences (ITDs) and the resulting reduced spatial hearing capabilities compared to normal-hearing individuals. This study aimed to investigate to what extent bilateral cochlear implant (BiCI) recipients can exploit ITD cues provided by a TFS preserving coding strategy (FS4) in a series of sound field spatial hearing tests. As a baseline, we assessed the sensitivity to ITDs and binaural beats of 12 BiCI subjects with a coding strategy disregarding fine structure (HDCIS) and the FS4 strategy. For 250 Hz pure-tone stimuli but not for broadband noise, the BiCI users had significantly improved ITD discrimination using the FS4 strategy. In the binaural beat detection task and the broadband sound localization, spatial discrimination, and tracking tasks, no significant differences between the two tested coding strategies were observed. These results suggest that ITD sensitivity did not generalize to broadband stimuli or sound field spatial hearing tests, suggesting that it would not be useful for real-world listening.

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Section: A Headphone-based Experimentsmentioning

confidence: 75%

Effects of temporal fine structure preservation on spatial hearing in bilateral cochlear implant users

Fischer

Schmid

Kompis

et al. 2021

The Journal of the Acoustical Society of America

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“…Unlike in normal-hearing listeners leveraging the advantages of ITD TFS , in bCI listeners, speech unmasking can be about equal for envelope cues, compared with fine-structure cues (van Hoesel et al, 2008). For bCI stimulation at high pulse rates typical of clinical CI processors, bCI listeners achieve about 9 dB of binaural unmasking when the temporal envelope is presented without fine structure using constant-rate pulses (Todd et al, 2019). This benefit from binaural envelope cues may be largely from IID with only minor support from ITD ENV , consistent with the much heavier weighting of IID than of ITD for localizing high-frequency sound, by the large majority of normal-hearing listeners (Macpherson & Middlebrooks, 2002).…”

Section: Implications For Listeners With Bilateral Cochlear Implantsmentioning

confidence: 99%

Sensitivity to Envelope Interaural Time Difference: Models of Diverse LSO Neurons

Brughera

Ballestero

McAlpine

2020

Preprint

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A potential auditory spatial cue, the envelope interaural time difference (ITDENV) is encoded in the lateral superior olive (LSO) of the brainstem. Here, we explore computationally modeled LSO neurons, in reflecting behavioral sensitivity to ITDENV. Transposed tones (half-wave rectified low-frequency tones, frequency-limited, then multiplying a high-frequency carrier) stimulate a bilateral auditory-periphery model driving each model LSO neuron, where electrical membrane impedance low-pass filters the inputs driven by amplitude-modulated sound, limiting the upper modulation rate for ITDENV sensitivity. Just-noticeable differences in ITDENV for model LSO neuronal populations, each distinct to reflect the LSO range in membrane frequency response, collectively reproduce the largest variation in ITDENV sensitivity across human listeners. At each stimulus carrier frequency (4-10 kHz) and modulation rate (32-800 Hz), the top-performing model population generally reflects top-range human performance. Model neurons of each speed are the top performers for a particular range of modulation rate. Off-frequency listening extends model ITDENV sensitivity above 500-Hz modulation, as sensitivity decreases with increasing modulation rate. With increasing carrier frequency, the combination of decreased top membrane speed and decreased number of model neurons capture decreasing human sensitivity to ITDENV.

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“…Researchers have developed specific speech processing strategies in an attempt to provide temporal fine-structure cues to bilateral CI users (Laback et al, 2015). Stimuli to both sides can be synchronized by using controlled electrical signals delivered by research processors (Todd et al, 2019). It is important to use these research processors when exploring the possibilities for bilateral CI users to use bilateral speech cues, but it does not give insight in the use of these cues in realistic listening situations with standard clinical speech processors.…”

Section: Binaural Unmaskingmentioning

confidence: 99%

Binaural summation, binaural unmasking and fluctuating masker benefit in bimodal and bilateral adult cochlear implant users

Graaff

Eikelboom

Sucher

et al. 2021

Cochlear Implants International

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Objectives: The number of bilateral adult cochlear implant (CI) users and bimodal CI users is expanding worldwide. The addition of a hearing aid (HA) in the contralateral non-implanted ear (bimodal) or a second CI (bilateral) can provide CI users with some of the benefits associated with listening with two ears. Our was to examine whether bilateral and bimodal CI users demonstrate binaural summation, binaural unmasking and a fluctuating masker benefit. Methods: Direct audio input was used to present stimuli to 10 bilateral and 10 bimodal Cochlear TM CI users. Speech recognition in noise (speech reception threshold, SRT) was assessed monaurally, diotically (identical signals in both devices) and dichotically (antiphasic speech) with different masking noises (steady-state and interrupted), using the digits-in-noise test.Results: Bilateral CI users demonstrated a trend towards better SRTs with both CIs than with one CI. Bimodal CI users showed no difference between the bimodal SRT and the SRT for CI alone. No significant differences in SRT were found between the diotic and dichotic conditions for either group. Analyses of electrodograms created from bilateral stimuli demonstrated that substantial parts of the interaural speech cues were preserved in the Advanced Combination Encoder, an n-of-m channel selection speech coding strategy, used by the CI users. Speech recognition in noise was significantly better with interrupted noise than with steady-state masking noise for both bilateral and bimodal CI users. Conclusion:Bilateral CI users demonstrated a trend towards binaural summation, but bimodal CI users did not. No binaural unmasking was demonstrated for either group of CI users. A large fluctuating masker benefit was found in both bilateral and bimodal CI users.

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Binaural unmasking with temporal envelope and fine structure in listeners with cochlear implants

Cited by 8 publications

References 44 publications

Effects of temporal fine structure preservation on spatial hearing in bilateral cochlear implant users

Effects of temporal fine structure preservation on spatial hearing in bilateral cochlear implant users

Sensitivity to Envelope Interaural Time Difference: Models of Diverse LSO Neurons

Binaural summation, binaural unmasking and fluctuating masker benefit in bimodal and bilateral adult cochlear implant users

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