The Effect of Temporal Gap Identification on Speech Perception by Users of Cochlear Implants

Sagi, Elad; Kaiser, Adam R.; Meyer, Ted A.; Svirsky, Mario A.

doi:10.1044/1092-4388(2008/07-0219)

Cited by 29 publications

(26 citation statements)

References 33 publications

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“…A number of studies have shown relationships between perceptual temporal processing and speech perception (e.g., Fu, 2002; Luo et al, 2008; Sagi et al, 2009). If temporal inputs from the auditory nerve are the basis for perceptual temporal processing, then the results from the present study may have implications for changes to future speech-processing strategies.…”

Section: Resultsmentioning

confidence: 99%

Temporal response properties of the auditory nerve: Data from human cochlear-implant recipients

et al. 2012

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The primary goal of this study was to characterize the variability in auditory-nerve temporal response patterns obtained with the electrically evoked compound action potential (ECAP) within and across a relatively large group of cochlear-implant recipients. ECAPs were recorded in response to each of 21 pulses in a pulse train for five rates (900, 1200, 1800, 2400, and 3500 pps) and three cochlear regions (basal, middle, and apical). An alternating amplitude pattern was typically observed across the pulse train for slower rates, reflecting refractory properties of individual nerve fibers. For faster rates, the alternation ceased and overall amplitudes were substantially lower relative to the first pulse in the train, reflecting cross-fiber desynchronization. The following specific parameters were examined: (1) the rate at which the alternating pattern ceased (termed stochastic rate), (2) the alternation depth and the rate at which the maximum alternation occurred, and (3) the average normalized ECAP amplitude across the pulse train (measure of overall adaptation/desynchronization). Data from 29 ears showed that stochastic rates for the group spanned the entire range of rates tested. The majority of subjects (79%) had different stochastic rates across the three cochlear regions. The stochastic rate occurred most frequently at 2400 pps for basal and middle electrodes, and at 3500 pps for apical electrodes. Stimulus level was significantly correlated with stochastic rate, where higher levels yielded faster stochastic rates. The maximum alternation depth averaged 19% of the amplitude for the first pulse. Maximum alternation occurred most often at 1800 pps for basal and apical electrodes, and at 1200 pps for middle electrodes. These differences suggest some independence between alternation depth and stochastic rate. Finally, the overall amount of adaptation or desynchronization ranged from 63% (for 900 pps) to 23% (for 3500 pps) of the amplitude for the first pulse. Differences in temporal response properties across the cochlea within subjects may have implications for developing new speech-processing strategies that employ varied rates across the array.

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Section: Resultsmentioning

confidence: 99%

Temporal response properties of the auditory nerve: Data from human cochlear-implant recipients

et al. 2012

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“…If the mechanisms underlying improvement of GDTs as a function of level are related to loudness percepts, then examining the latter might improve temporal gap detection in CI users. There is a growing body of evidence suggesting a relation between GDTs and speech recognition (Muchnik et al, 1994; Sagi et al, 2009). Hence, the extent to which CI recipients are able to resolve temporal information, including their ability to detect a silent gap, should be maximized with the expectation that their speech performance would also improve.…”

Section: Discussionmentioning

confidence: 99%

Relationship between gap detection thresholds and loudness in cochlear-implant users

Garadat

Pfingst

2011

Hearing Research

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Gap detection threshold (GDT) is a commonly used measure of temporal acuity in cochlear implant (CI) recipients. This measure, like other measures of temporal acuity, shows considerable variation across subjects and also varies across stimulation sites within subjects. The aims of this study were (1) to determine whether across-site variation in GDTs would be reduced or maintained with increased stimulation levels; (2) to determine whether across-site variation in GDTs at low stimulation levels was related to differences in loudness percepts at those same levels; and (3) to determine whether matching loudness levels could reduce across-site differences in GDTs. Thresholds and maximum comfortable loudness levels were measured in postlingually deaf adults using all available sites in their electrode arrays. All sites were then surveyed at 30% of the dynamic range (DR) to examine across-site variation. Two sites with the largest difference in GDTs were then selected and for those two sites GDTs were measured at multiple levels of the DR (10%, 30%, 50%, 70%, and 90%). Stimuli consisted of 500 ms trains of symmetric-biphasic pulses, 40 μs/phase, presented at a rate of 1000 pps using a monopolar (MP1+2) electrode configuration. To examine perceptual differences in loudness, the selected sites were loudnessmatched at the same levels of the DR. Variations in GDTs and loudness patterns were observed across stimulation sites and across subjects. Variations in GDTs across sites tended to decrease with increasing stimulation levels. For the majority of the subjects, stimuli at a given level in %DR were perceived louder at sites with better GDTs than those presented at the same level in %DR at sites with poorer GDTs. These results suggest that loudness is a contributing factor to across-site variation in GDTs and that CI fittings based on more detailed loudness matching could reduce across-site variation and improve perceptual acuity.

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“…Although channel vocoding preserves the amplitude difference between primary-and secondary-stressed target words, listeners did not use this cue to lexical stress in the vocoder condition. There are several possible explanations for this result: (1) the small difference in amplitude may not be sufficient to help in distinguishing primary and secondary stress, (2) amplitude is not a reliable cue to the degree of lexical stress (e.g., Beckman, 1986;Fear et al, 1995;Mattys, 2000;Sluijter and Van Heuven, 1996) and seems to be a less important cue for lexical stress in English (e.g., Chrabaszcz et al, 2014;Fry, 1955Fry, , 1958Lehiste, 1970;Mattys, 2000), and/or (3) listeners' ability to perceive slight temporal and intensity changes in the spectrally degraded signal is reduced, as suggested by previous vocoder and CI studies (Oxenham and Kreft, 2014;Rogers et al, 2006;Sagi et al, 2009;Won et al, 2011).…”

Section: Discussionmentioning

confidence: 88%

Low-frequency fine-structure cues allow for the online use of lexical stress during spoken-word recognition in spectrally degraded speech

Kong

Jesse

2017

The Journal of the Acoustical Society of America

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English listeners use suprasegmental cues to lexical stress during spoken-word recognition. Prosodic cues are, however, less salient in spectrally degraded speech, as provided by cochlear implants. The present study examined how spectral degradation with and without low-frequency fine-structure information affects normal-hearing listeners' ability to benefit from suprasegmental cues to lexical stress in online spoken-word recognition. To simulate electric hearing, an eight-channel vocoder spectrally degraded the stimuli while preserving temporal envelope information. Additional lowpass-filtered speech was presented to the opposite ear to simulate bimodal hearing. Using a visual world paradigm, listeners' eye fixations to four printed words (target, competitor, two distractors) were tracked, while hearing a word. The target and competitor overlapped segmentally in their first two syllables but mismatched suprasegmentally in their first syllables, as the initial syllable received primary stress in one word and secondary stress in the other (e.g., "'admiral," ""admi'ration"). In the vocoder-only condition, listeners were unable to use lexical stress to recognize targets before segmental information disambiguated them from competitors. With additional lowpass-filtered speech, however, listeners efficiently processed prosodic information to speed up online word recognition. Low-frequency fine-structure cues in simulated bimodal hearing allowed listeners to benefit from suprasegmental cues to lexical stress during word recognition.

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The Effect of Temporal Gap Identification on Speech Perception by Users of Cochlear Implants

Cited by 29 publications

References 33 publications

Temporal response properties of the auditory nerve: Data from human cochlear-implant recipients

Temporal response properties of the auditory nerve: Data from human cochlear-implant recipients

Relationship between gap detection thresholds and loudness in cochlear-implant users

Low-frequency fine-structure cues allow for the online use of lexical stress during spoken-word recognition in spectrally degraded speech

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