The effects of adaptive directional microphone on auditory evoked cortical P300 response and speech performance in cochlear implant users

Mismatch negativity as a marker of music perception in individual cochlear implant users: A spike density component analysis study

OBJECTIVE

Ninety percent of cochlear implant (CI) users are interested in improving their music perception. However, only few objective behavioral and neurophysiological tests have been developed for tracing the development of music discrimination skills in CI users. In this study, we aimed to obtain an accurate individual mismatch negativity (MMN) marker that could predict behavioral auditory discrimination thresholds.

METHODS

We measured the individual MMN response to four magnitudes of deviations in four different musical features (intensity, pitch, timbre, and rhythm) in a rare sample of experienced CI users and a control sample of normally hearing participants. We applied a recently developed spike density component analysis (SCA), which can suppress confounding alpha waves, and contrasted it with previously proposed methods.

RESULTS

Statistically detected individual MMN predicted attentive sound discrimination ability with high accuracy: for CI users 89.2% (278/312 cases) and for controls 90.5% (384/424 cases). As expected, MMN was detected for fewer CI users when the sound deviants were of smaller magnitude.

CONCLUSIONS

The findings support the use of MMN responses in individual CI users as a diagnostic tool for testing music perception.

SIGNIFICANCE

For CI users, the new SCA method provided more accurate and replicable diagnostic detections than preceding state-of-the-art.

Is there a change in P300 evoked potential after 6 months in cochlear implant users?

OBJECTIVE

There are few studies on long-latency auditory evoked potential (P300) in people with hearing loss who use a cochlear implant. Central auditory system evaluation with behavioral and electrophysiological tests is believed to help understand the neuroplasticity mechanisms involved in auditory functioning after cochlear implant surgery. This study investigated the electrophysiological processing of cortical level acoustic signals in a group of 21 adult individuals with postlingual bilateral severe-to-profound hearing loss who were submitted to cochlear implant surgery.

METHODS

Data were collected in three phases: pre-cochlear implant surgery, at cochlear implant activation, and 6 months after surgery. P300 measures were also registered during all phases. Tone-burst and speech stimuli were used to elicit P300 and were presented in free field.

RESULTS

Mean P3 component latency with tone-burst and speech stimuli were 352.9 and 321.9 ms in the pre-cochlear implant phase, 364.9 and 368.7 ms in the activation phase, 336.2 and 343.6 ms 6 months after the surgery. The P3 component mean latency values using tone-burst at activation were significantly different from those 6 months after cochlear implant. They were also significantly different using speech, between pre-cochlear implant and activation phases. Lower P3 component latency occurred 6 months after cochlear implant activation with tone-burst and pre-cochlear implant with speech stimulus. There was a weak correlation between mean P3 component latency with speech stimulus and time of hearing loss. There was no difference in amplitude between phases or in the comparison with the other variables.

CONCLUSION

There were changes in P3 component latency during the period assessed, for both speech and pure-tone stimuli, with increased latency in the activation phase and similar lower results in the two other phases, Pre-CI and 6 months after CI use. Mean amplitude measures did not vary in the three phases.

Cross-cultural adaptation of the Nijmegen cochlear implant questionnaire into Turkish language: validity, reliability and effects of demographic variables

Purpose

The purpose of this study was to evaluate the validity and reliability of the Turkish version of the Nijmegen Cochlear Implant Questionnaire (Tr-NCIQ) and reveal the demographic factors contributing to the outcomes.

Methods

A group of 118 cochlear implant users aged between 18 and 70 years filled the Tr-NCIQ and the Turkish Hearing Handicapped Inventory for Adults (the Tr-HHI-Adult) via electronic survey. Cross-cultural adaptation of the Tr-NCIQ was performed. The reliability and validity of the questionnaire were evaluated utilizing internal consistency coefficient, split-half method, and predictive validity.

Results

The overall Cronbach’s alpha coefficient of the scale was 0.91, and the Spearman-Brown coefficient was 0.91. A moderately significant and negative correlation was present between the basic sound perception, speech production, self-esteem, activity, and social interactions subdomain scores and the HHI-Adult scores. Patients with post-lingual onset of hearing loss had significantly better results than those with pre-lingual onset, in the advanced sound perception subdomain. In addition, bilateral cochlear implant users had better results than the unilateral and bimodal users in the speech production subdomain and then the bimodal users in the self-esteem subdomain. There was no effect of age, duration of implant use, age at implantation, and the daily usage of cochlear implant (CI) on the quality-of-life outcomes.

Conclusion

The Tr-NCIQ is a reliable and valid tool to evaluate the subjective quality of life in CI users. In addition, as a standardized instrument, it can be easily self-administered both in clinical practice and for research purposes.