Improved Speech Perception in Cochlear Implant Users With Interleaved High-Rate Pulse Trains.

OBJECTIVE: Electrical stimulation with a cochlear implant (CI) elicits abnormally high neural synchrony, which poses significant challenges for speech perception. Previous investigations showed that constant-amplitude high-rate pulse trains (HRPs) desynchronize neural responses and improve stimulus encoding. The study objective was to investigate the effects of HRP on speech perception in adult CI users. STUDY DESIGN: Prospective, within-subject design. SETTING: Tertiary CI center. PATIENTS: Ten adult CI recipients. INTERVENTION: Sentence stimuli were created by modifying a basic continuous interleaved sampling (CIS) strategy (1,000 pulses per second; pps) with interleaved biphasic pulse trains (3,000 pps) on even electrodes. Institute of Electrical and Electronics Engineers sentences in quiet and in noise were tested without HRP, and with HRPs of various stimulation levels. MAIN OUTCOME MEASURE: Sentence perception in percent correct was calculated for all conditions. The highest speech perception score with HRP stimulation was defined as "max-HRP." RESULTS: Group analyses showed significantly improved sentence perception in background noise with HRPs (p < 0.001). There was no significant difference for sentence perception in quiet for the group. However, seven of 10 subjects experienced some benefit from HRP stimuli in quiet and the degree of HRP benefit showed significant relationships with baseline performance and age at implantation, indicating that HRP stimuli may be most beneficial for older patients or poorer performers. CONCLUSIONS: Significant improvement in speech perception in noise was observed with HRP stimuli. Some recipients may also benefit from HRP stimulation in quiet. Interleaved HRPs hold promise as a novel stimulation paradigm with clinical sound processing strategies to improve patient performance.

Multicenter US Clinical Trial With an Electric-Acoustic Stimulation (EAS) System in Adults: Final Outcomes.

OBJECTIVE: To demonstrate the safety and effectiveness of the MED-EL Electric-Acoustic Stimulation (EAS) System, for adults with residual low-frequency hearing and severe-to-profound hearing loss in the mid to high frequencies. STUDY DESIGN: Prospective, repeated measures. SETTING: Multicenter, hospital. PATIENTS: Seventy-three subjects implanted with PULSAR or SONATA cochlear implants with FLEX electrode arrays. INTERVENTION: Subjects were fit postoperatively with an audio processor, combining electric stimulation and acoustic amplification. MAIN OUTCOME MEASURES: Unaided thresholds were measured preoperatively and at 3, 6, and 12 months postactivation. Speech perception was assessed at these intervals using City University of New York sentences in noise and consonant-nucleus-consonant words in quiet. Subjective benefit was assessed at these intervals via the Abbreviated Profile of Hearing Aid Benefit and Hearing Device Satisfaction Scale questionnaires. RESULTS: Sixty-seven of 73 subjects (92%) completed outcome measures for all study intervals. Of those 67 subjects, 79% experienced less than a 30 dB HL low-frequency pure-tone average (250-1000 Hz) shift, and 97% were able to use the acoustic unit at 12 months postactivation. In the EAS condition, 94% of subjects performed similarly to or better than their preoperative performance on City University of New York sentences in noise at 12 months postactivation, with 85% demonstrating improvement. Ninety-seven percent of subjects performed similarly or better on consonant-nucleus-consonant words in quiet, with 84% demonstrating improvement. CONCLUSION: The MED-EL EAS System is a safe and effective treatment option for adults with normal hearing to moderate sensorineural hearing loss in the low frequencies and severe-to-profound sensorineural hearing loss in the high frequencies who do not benefit from traditional amplification.

Differences in Perception of Musical Stimuli among Acoustic, Electric, and Combined Modality Listeners.

BACKGROUND: Cochlear implants have shown vast improvements in speech understanding for those with severe to profound hearing loss; however, music perception remains a challenge for electric hearing. It is unclear whether the difficulties arise from limitations of sound processing, the nature of a damaged auditory system, or a combination of both. PURPOSE: To examine music perception performance with different acoustic and electric hearing configurations. RESEARCH DESIGN: Chord discrimination and timbre perception were tested in subjects representing four daily-use listening configurations: unilateral cochlear implant (CI), contralateral bimodal (CIHA), bilateral hearing aid (HAHA) and normal-hearing (NH) listeners. A same-different task was used for discrimination of two chords played on piano. Timbre perception was assessed using a 10-instrument forced-choice identification task. STUDY SAMPLE: Fourteen adults were included in each group, none of whom were professional musicians. DATA COLLECTION AND ANALYSIS: The number of correct responses was divided by the total number of presentations to calculate scores in percent correct. Data analyses were performed with Kruskal-Wallis one-way analysis of variance and linear regression. RESULTS: Chord discrimination showed a narrow range of performance across groups, with mean scores ranging between 72.5% (CI) and 88.9% (NH). Significant differences were seen between the NH and all hearing-impaired groups. Both the HAHA and CIHA groups performed significantly better than the CI groups, and no significant differences were observed between the HAHA and CIHA groups. Timbre perception was significantly poorer for the hearing-impaired groups (mean scores ranged from 50.3-73.9%) compared to NH (95.2%). Significantly better performance was observed in the HAHA group as compared to both groups with electric hearing (CI and CIHA). There was no significant difference in performance between the CIHA and CI groups. Timbre perception was a significantly more difficult task than chord discrimination for both the CI and CIHA groups, yet the easier task for the NH group. A significant difference between the two tasks was not seen in the HAHA group. CONCLUSIONS: Having impaired hearing decreases performance compared to NH across both chord discrimination and timbre perception tasks. For chord discrimination, having acoustic hearing improved performance compared to electric hearing only. Timbre perception distinguished those with acoustic hearing from those with electric hearing. Those with bilateral acoustic hearing, even if damaged, performed significantly better on this task than those requiring electrical stimulation, which may indicate that CI sound processing fails to capture and deliver the necessary acoustic cues for timbre perception. Further analysis of timbre characteristics in electric hearing may contribute to advancements in programming strategies to obtain optimal hearing outcomes.

Recovery from forward masking in elderly cochlear implant users.

OBJECTIVE: To compare temporal aspects of peripheral neural responses and central auditory perception between groups of younger adult and elderly cochlear implant users. STUDY DESIGN: Cohort study. SETTING: Academic hospital and cochlear implant center. PATIENTS: Adult cochlear implant users aged 28 to 57 years in the younger group (n = 5) and 61 to 89 years (n = 9) in the elderly group. All subjects used Advanced Bionics devices. INTERVENTION: Diagnostic. MAIN OUTCOME MEASURES: Time constants of neural (i.e., electrically evoked compound action potentials [ECAPs]) and perceptual recovery from forward masking. Interstimulus intervals (ISIs) were varied in both experiments. RESULTS: ECAP recovery rates were equivalent between groups, and no correlation was found between ECAP recovery and age. No correlations were found between ECAP recovery and speech perception. Psychophysical recovery was significantly slower in the elderly compared with the younger subjects (p < 0.0005), with a significant effect of age (R2 = 0.70, p < 0.0005). At the longest ISI (240 ms), elderly subjects experienced a mean maximum threshold shift of 35.2% (relative to 1 ms ISI) versus 14.8% for younger subjects. There was a significant positive relationship between psychophysical recovery and consonant-nucleus-consonant word scores (R2 = 0.62, p < 0.001), although no relationship was found with Hearing in Noise Test sentences. CONCLUSION: These findings suggest that difficulties observed in speech perception by elderly CI users may be due to age-related changes in the central rather than peripheral auditory system. With further study, these results may provide information to allow clinicians to assess patients' temporal processing abilities and facilitate setting program parameters that will maximize their auditory perceptual experience with a cochlear implant.