The ability of cochlear implant users to use temporal envelope cues recovered from speech frequency modulation

Electrical stimulation of vestibular afferent neurons to partially restore semicircular canal sensation of head rotation and the stabilizing reflexes that sensation supports has potential to effectively treat individuals disabled by bilateral vestibular hypofunction. Ideally, a vestibular implant system using this approach would be integrated with a cochlear implant, which would provide clinicians with a means to simultaneously treat loss of both vestibular and auditory sensation. Despite obvious similarities, merging these technologies poses several challenges, including stimulus pulse timing errors that arise when a system must implement a pulse frequency modulation-encoding scheme (as is used in vestibular implants to mimic normal vestibular nerve encoding of head movement) within fixed-rate continuous interleaved sampling (CIS) strategies used in cochlear implants. Pulse timing errors caused by temporal discretization inherent to CIS create stair step discontinuities of the vestibular implant’s smooth mapping of head velocity to stimulus pulse frequency. In this study, we assayed electrically evoked vestibuloocular reflex responses in two rhesus macaques using both a smooth pulse frequency modulation map and a discretized map corrupted by temporal errors typical of those arising in a combined cochlear-vestibular implant. Responses were measured using three-dimensional scleral coil oculography for prosthetic electrical stimuli representing sinusoidal head velocity waveforms that varied over 50–400°/s and 0.1–5 Hz. Pulse timing errors produced negligible effects on responses across all canals in both animals, indicating that temporal discretization inherent to implementing a pulse frequency modulation-coding scheme within a cochlear implant’s CIS fixed pulse timing framework need not sacrifice performance of the combined system’s vestibular implant portion. NEW & NOTEWORTHY Merging a vestibular implant system with existing cochlear implant technology can provide clinicians with a means to restore both vestibular and auditory sensation. Pulse timing errors inherent to integration of pulse frequency modulation vestibular stimulation with fixed-rate, continuous interleaved sampling cochlear implant stimulation would discretize the smooth head velocity encoding of a combined device. In this study, we show these pulse timing errors produce negligible effects on electrically evoked vestibulo-ocular reflex responses in two rhesus macaques.

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Sensitivity to binaural temporal-envelope beats with single-sided deafness and a cochlear implant as a measure of tonotopic match (L)

The Journal of the Acoustical Society of America ◽

10.1121/10.0001305 ◽

2020 ◽

Vol 147 (5) ◽

pp. 3626-3630

Author(s):

Coral E. Dirks ◽

Peggy B. Nelson ◽

Matthew B. Winn ◽

Andrew J. Oxenham

Keyword(s):

Cochlear Implant ◽

Temporal Envelope ◽

Single Sided Deafness

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Cochlear implant employing frequency‐division multiplexing and frequency modulation

The Journal of the Acoustical Society of America ◽

10.1121/1.405274 ◽

1992 ◽

Vol 92 (3) ◽

pp. 1796-1796

Author(s):

Dean C. Jeutter ◽

Fabien J. Josse ◽

James C. Han

Keyword(s):

Cochlear Implant ◽

Frequency Modulation ◽

Frequency Division Multiplexing ◽

Frequency Division

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Discrimination of Stochastic Frequency Modulation by Cochlear Implant Users

Journal of the American Academy of Audiology ◽

10.3766/jaaa.14067 ◽

2015 ◽

Vol 26 (06) ◽

pp. 572-581 ◽

Cited By ~ 3

Author(s):

Stanley Sheft ◽

Min-Yu Cheng ◽

Valeriy Shafiro

Keyword(s):

Speech Perception ◽

Cochlear Implant ◽

Stimulus Duration ◽

Frequency Modulation ◽

Speech Intelligibility ◽

Signal To Noise Ratio ◽

Normal Hearing ◽

Signal To Noise ◽

Common Basis ◽

Low Rate

Background: Past work has shown that low-rate frequency modulation (FM) may help preserve signal coherence, aid segmentation at word and syllable boundaries, and benefit speech intelligibility in the presence of a masker. Purpose: This study evaluated whether difficulties in speech perception by cochlear implant (CI) users relate to a deficit in the ability to discriminate among stochastic low-rate patterns of FM. Research Design: This is a correlational study assessing the association between the ability to discriminate stochastic patterns of low-rate FM and the intelligibility of speech in noise. Study Sample: Thirteen postlingually deafened adult CI users participated in this study. Data Collection and Analysis: Using modulators derived from 5-Hz lowpass noise applied to a 1-kHz carrier, thresholds were measured in terms of frequency excursion both in quiet and with a speech-babble masker present, stimulus duration, and signal-to-noise ratio in the presence of a speech-babble masker. Speech perception ability was assessed in the presence of the same speech-babble masker. Relationships were evaluated with Pearson product–moment correlation analysis with correction for family-wise error, and commonality analysis to determine the unique and common contributions across psychoacoustic variables to the association with speech ability. Results: Significant correlations were obtained between masked speech intelligibility and three metrics of FM discrimination involving either signal-to-noise ratio or stimulus duration, with shared variance among the three measures accounting for much of the effect. Compared to past results from young normal-hearing adults and older adults with either normal hearing or a mild-to-moderate hearing loss, mean FM discrimination thresholds obtained from CI users were higher in all conditions. Conclusions: The ability to process the pattern of frequency excursions of stochastic FM may, in part, have a common basis with speech perception in noise. Discrimination of differences in the temporally distributed place coding of the stimulus could serve as this common basis for CI users.

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