Cortical Encoding of Pitch Contour Changes in Cochlear Implant Users: A Mismatch Negativity Study

This paper describes a logatome discrimination test for the assessment of speech perception in cochlear implant users (CI users), based on a multilingual speech database, the Oldenburg Logatome Corpus, which was originally recorded for the comparison of human and automated speech recognition. The logatome discrimination task is based on the presentation of 100 logatome pairs (i.e., nonsense syllables) with balanced representations of alternating “vowel-replacement” and “consonant-replacement” paradigms in order to assess phoneme confusions. Thirteen adult normal hearing listeners and eight adult CI users, including both good and poor performers, were included in the study and completed the test after their speech intelligibility abilities were evaluated with an established sentence test in noise. Furthermore, the discrimination abilities were measured electrophysiologically by recording the mismatch negativity (MMN) as a component of auditory event-related potentials. The results show a clear MMN response only for normal hearing listeners and CI users with good performance, correlating with their logatome discrimination abilities. Higher discrimination scores for vowel-replacement paradigms than for the consonant-replacement paradigms were found. We conclude that the logatome discrimination test is well suited to monitor the speech perception skills of CI users. Due to the large number of available spoken logatome items, the Oldenburg Logatome Corpus appears to provide a useful and powerful basis for further development of speech perception tests for CI users.

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Saliency of Vowel Features in Neural Responses of Cochlear Implant Users

Clinical EEG and Neuroscience ◽

10.1177/1550059418770051 ◽

2018 ◽

Vol 49 (6) ◽

pp. 388-397

Author(s):

François Prévost ◽

Alexandre Lehmann

Keyword(s):

Speech Recognition ◽

Cochlear Implant ◽

Fundamental Frequency ◽

Mismatch Negativity ◽

Free Field ◽

Event Related Potentials ◽

Oddball Paradigm ◽

Aural Rehabilitation ◽

Spectral Components ◽

Related Potentials

Cochlear implants restore hearing in deaf individuals, but speech perception remains challenging. Poor discrimination of spectral components is thought to account for limitations of speech recognition in cochlear implant users. We investigated how combined variations of spectral components along two orthogonal dimensions can maximize neural discrimination between two vowels, as measured by mismatch negativity. Adult cochlear implant users and matched normal-hearing listeners underwent electroencephalographic event-related potentials recordings in an optimum-1 oddball paradigm. A standard /a/ vowel was delivered in an acoustic free field along with stimuli having a deviant fundamental frequency (+3 and +6 semitones), a deviant first formant making it a /i/ vowel or combined deviant fundamental frequency and first formant (+3 and +6 semitones /i/ vowels). Speech recognition was assessed with a word repetition task. An analysis of variance between both amplitude and latency of mismatch negativity elicited by each deviant vowel was performed. The strength of correlations between these parameters of mismatch negativity and speech recognition as well as participants’ age was assessed. Amplitude of mismatch negativity was weaker in cochlear implant users but was maximized by variations of vowels’ first formant. Latency of mismatch negativity was later in cochlear implant users and was particularly extended by variations of the fundamental frequency. Speech recognition correlated with parameters of mismatch negativity elicited by the specific variation of the first formant. This nonlinear effect of acoustic parameters on neural discrimination of vowels has implications for implant processor programming and aural rehabilitation.

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Mismatch Negativity in Children with Cochlear Implant

International Archives of Otorhinolaryngology ◽

10.1055/s-0039-1688967 ◽

2019 ◽

Vol 23 (03) ◽

pp. e292-e298

Author(s):

Natalia Martinez Fernandes ◽

Daniela Gil ◽

Marisa Frasson de Azevedo

Keyword(s):

Speech Perception ◽

Language Development ◽

Cochlear Implant ◽

Cochlear Implants ◽

Family Involvement ◽

Mismatch Negativity ◽

Control Group ◽

Study Group ◽

Cross Sectional ◽

Hearing Children

Introduction The mismatch negativity (MMN) is a negative long-latency auditory potential elicited by any discriminable change in a repetitive aspect of auditory stimulation. This evoked potential can provide cortical information about the sound processing, including in children who use cochlear implants. Objective To identify MMN characteristics regarding latency, amplitude, and wave area in cochlear implanted children and to identify associations among language development, speech perception and family involvement. Methods This is a descriptive, observational, cross-sectional study, which compared two groups: study group—children with cochlear implant, and control group—hearing children. The children were submitted to MMN evaluation with non-verbal tone burst stimulus, differing in frequency in sound field at 70 dBHL, with SmartEP equipment (Intelligent Hearing Systems, Miami, FL, USA). Speech perception and language development questionnaires were also applied, and the family participation in the rehabilitation process was classified. Results The occurrence of MMN was 73.3% for the control group and 53.3% for the study group. Values of latency, amplitude and area of MMN of children using cochlear implants were similar to those of hearing children, and did not differ between groups. The occurrence of MMN was not correlated to the variables of hearing, language and family categories. Conclusion Children with cochlear implants showed similar MMN responses to those of the children in the control group, with mean latency, amplitude and area of 208.9 ms (±12.8), -2.37 μV (±0.38) and 86.5 μVms (±23.4), respectively. There was no correlation between the presence of MMN and children's performance in the auditory and language development tests or family involvement during rehabilitation.

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