Influence of Electric Frequency-to-Place Mismatches on the Early Speech Recognition Outcomes for Electric-Acoustic Stimulation Users.

PURPOSE: Cochlear implant (CI) recipients with hearing preservation experience significant improvements in speech recognition with electric-acoustic stimulation (EAS) as compared to with a CI alone, although outcomes across EAS users vary. The individual differences in performance may be due in part to default mapping procedures, which result in electric frequency-to-place mismatches for the majority of EAS users. This study assessed the influence of electric mismatches on the early speech recognition for EAS users. METHOD: Twenty-one participants were randomized at EAS activation to listen exclusively with a default or place-based map. For both groups, the unaided thresholds determined the acoustic cutoff frequency (i.e., > 65 dB HL). For default maps, the electric filter frequencies were assigned to avoid spectral gaps in frequency information but created varying magnitudes of mismatches. For place-based maps, the electric filter frequencies were assigned to avoid frequency-to-place mismatches. Recognition of consonant-nucleus-consonant words and vowels was assessed at activation and 1, 3, and 6 months postactivation. RESULTS: For participants with default maps, electric mismatch at 1500 Hz ranged from 2 to -12.0 semitones (Mdn = -5 semitones). Poorer performance was observed for those with larger magnitudes of electric mismatch. This effect was observed through 6 months of EAS listening experience. CONCLUSIONS: The present sample of EAS users experienced better initial performance when electric mismatches were small or eliminated. These data suggest the utility of methods that reduce electric mismatches, such as place-based mapping procedures. Investigation is ongoing to determine whether these differences persist with long-term EAS use. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.22096523.

Cochlear Implantation for Unilateral and Asymmetric Hearing Loss: Long-Term Subjective Benefit.

OBJECTIVES: Assess the long-term patterns of perceived tinnitus severity and subjective benefit for adult cochlear implant (CI) users with asymmetric or unilateral hearing loss (AHL or UHL). METHODS: Forty adults underwent cochlear implantation as part of a prospective clinical trial assessing the outcomes of CI use in cases of AHL (n = 20) and UHL (n = 20). Subjective measures included the Tinnitus Handicap Inventory (THI), the Speech, Spatial, & Qualities of Hearing Scale (SSQ), and the Abbreviated Profile of Hearing Aid Benefit (APHAB). Responses were obtained preoperatively and at routine intervals out to 5 years post-activation. RESULTS: For subjective benefit, participants with AHL and UHL reported a significant improvement as compared to preoperative abilities, which was maintained with long-term CI use. For perceived tinnitus severity, participants with AHL and UHL reported a significant reduction with CI use as compared to preoperative perceptions. The perceived tinnitus severity significantly differed for the AHL and UHL cohorts over time. This pattern of results is likely influenced by the worse perceived severity levels for the UHL cohort preoperatively and the fluctuating perceived severity levels for some participants in the AHL cohort post-activation. CONCLUSION: Adults with AHL and UHL report an early, significant reduction in perceived tinnitus severity and improvement in quality of life with CI use that is generally maintained with long-term device use. Questionnaires such as the THI, SSQ, and APHAB may contribute to a more holistic assessment of the benefits of cochlear implantation in this population. LEVEL OF EVIDENCE: 2 Laryngoscope, 133:2792-2797, 2023.

Cochlear implantation for paediatric and adult cases of unilateral and asymmetric hearing loss.

PURPOSE OF REVIEW: Children and adults with unilateral or asymmetric hearing loss (UHL/AHL) have poorer spatial hearing (e.g. speech understanding in complex maskers and localization) and quality of life compared with peers with normal hearing bilaterally. Patients with UHL/AHL experience limited benefits with contralateral-routing technologies (e.g. bone conduction, CROS hearing aid systems). Cochlear implantation allows for stimulation of the auditory pathway for the poorer hearing ear. The present study reviews the recent literature on outcomes of cochlear implant use for recipients with UHL/AHL. RECENT FINDINGS: Recent research corroborates previous investigations of the significant benefits on measures of spatial hearing, tinnitus severity and quality of life for adult cochlear implant recipients. These benefits are also observed in pediatric cochlear implant recipients, with an association of better outcomes with younger ages at implantation for congenital cases and shorter durations of UHL/AHL for acquired cases. In addition, randomized trials demonstrate better outcomes with cochlear implant use versus contralateral-routing technologies. SUMMARY: Cochlear implantation supports better spatial hearing and quality of life in children and adults with UHL/AHL as compared to alternative listening conditions. Current research supports the expansion of candidacy criteria and insurance coverage for cochlear implantation for patients with UHL/AHL to improve their binaural hearing.

Low-Frequency Hearing Preservation With Long Electrode Arrays: Inclusion of Unaided Hearing Threshold Assessment in the Postoperative Test Battery.

Purpose The goal of this work was to evaluate the low-frequency hearing preservation of long electrode array cochlear implant (CI) recipients. Method Twenty-five participants presented with an unaided hearing threshold of ≤ 80 dB HL at 125 Hz pre-operatively in the ear to be implanted. Participants were implanted with a long (31.5-mm) electrode array. The unaided hearing threshold at 125 Hz was compared between the preoperative and postoperative intervals (i.e., initial CI activation, and 1, 3, 6, 9, and 12 months after activation). Results Eight participants maintained an unaided hearing threshold of ≤ 80 dB HL at 125 Hz postoperatively. The majority (n = 5) demonstrated aidable low-frequency hearing at initial activation, whereas 3 other participants experienced an improvement in unaided low-frequency hearing thresholds at subsequent intervals. Conclusions CI recipients can retain residual hearing sensitivity with fully inserted long electrode arrays, and low-frequency hearing thresholds may improve during the postoperative period. Therefore, unaided hearing thresholds obtained within the initial weeks after surgery may not reflect later hearing sensitivity. Routine measurement of postoperative unaided hearing thresholds-even for patients who did not demonstrate aidable hearing thresholds initially after cochlear implantation-will identify CI recipients who may benefit from electric-acoustic stimulation. Supplemental Material https://doi.org/10.23641/asha.11356637.

Low-Frequency Pitch Perception in Cochlear Implant Recipients With Normal Hearing in the Contralateral Ear.

Purpose Three experiments were carried out to evaluate the low-frequency pitch perception of adults with unilateral hearing loss who received a cochlear implant (CI). Method Participants were recruited from a cohort of CI users with unilateral hearing loss and normal hearing in the contralateral ear. First, low-frequency pitch perception was assessed for the 5 most apical electrodes at 1, 3, 6, and 12 months after CI activation using an adaptive pitch-matching task. Participants listened with a coding strategy that presents low-frequency temporal fine structure (TFS) and compared the pitch to that of an acoustic target presented to the normal hearing ear. Next, participants listened with an envelope-only, continuous interleaved sampling strategy. Pitch perception was compared between coding strategies to assess the influence of TFS cues on low-frequency pitch perception. Finally, participants completed a vocal pitch-matching task to corroborate the results obtained with the adaptive pitch-matching task. Results Pitch matches roughly corresponded to electrode center frequencies (CFs) in the CI map. Adaptive pitch matches exceeded the CF for the most apical electrode, an effect that was larger for continuous interleaved sampling than TFS. Vocal pitch matches were variable but correlated with the CF of the 3 most apical electrodes. There was no evidence that pitch matches changed between the 1- and 12-month intervals. Conclusions Relatively accurate and asymptotic pitch perception was observed at the 1-month interval, indicating either very rapid acclimatization or the provision of familiar place and rate cues. Early availability of appropriate pitch cues could have played a role in the early improvements in localization and masked speech recognition previously observed in this cohort. Supplemental Material https://doi.org/10.23641/asha.8862389.

Electric-Acoustic Stimulation After Reimplantation: Hearing Preservation and Speech Perception.

OBJECTIVE: Hearing preservation after cochlear implantation allows for fitting of acoustic and cochlear implant technologies in the same ear, known as Electric-Acoustic Stimulation (EAS). Cochlear implant recipients with EAS who experience an internal device failure face the additional risk of residual hearing loss during reimplantation. This report reviews the case of an EAS recipient with long-term hearing preservation and significant benefit who experienced a device failure and underwent cochlear reimplantation. PATIENT: Case study who presented with an internal device failure after nearly 10 years of hearing preservation and significant benefit with an EAS device. INTERVENTION: Reimplantation with hearing preservation electrode array. MAIN OUTCOME MEASURES: Unaided residual hearing and aided speech perception with an EAS device using CNC words in quiet and CUNY sentences in noise. RESULTS: Low-frequency thresholds were similar when comparing residual hearing pre- and post-reimplantation. The patient does not use the acoustic portion of the EAS device due to normal low-frequency hearing sensitivity-even after two cochlear implantation procedures. At the 3-month follow-up interval, the patient demonstrated restoration of aided speech perception performance with the EAS device. CONCLUSIONS: Hearing preservation can be maintained with long-term use of EAS devices. Those with preserved low-frequency hearing who experience a device failure may maintain hearing preservation after reimplantation. Normal low-frequency hearing thresholds were maintained in the present case, and the patient continued to listen with the EAS device without the acoustic component. EAS recipients may experience rapid restoration in speech perception after reimplantation in the presence of hearing preservation.

Electric-Acoustic Stimulation Outcomes in Children.

OBJECTIVES: This study investigates outcomes in children fit with electric-acoustic stimulation (EAS) and addresses three main questions: (1) Are outcomes with EAS superior to outcomes with conventional electric-only stimulation in children? (2) Do children with residual hearing benefit from EAS and conventional electric-only stimulation when compared with the preoperative hearing aid (HA) condition? (3) Can children with residual hearing derive benefit from EAS after several years of listening with conventional electric-only stimulation? DESIGN: Sixteen pediatric cochlear implant (CI) recipients between 4 and 16 years of age with an unaided low-frequency pure tone average of 75 dB HL in the implanted ear were included in two study arms. Arm 1 included new recipients, and Arm 2 included children with at least 1 year of CI experience. Using a within-subject design, participants were evaluated unilaterally with the Consonant-Nucleus-Consonant (CNC) word list in quiet and the Baby Bio at a +5 dB SNR using an EAS program and a conventional full electric (FE) program. Arm 1 participants' scores were also compared with preoperative scores. RESULTS: Speech perception outcomes were statistically higher with the EAS program than the FE program. For new recipients, scores were significantly higher with EAS than preoperative HA scores for both the CNC and Baby Bio in noise; however, after 6 months of device use, results in the FE condition were not significantly better than preoperative scores. Long-term FE users benefited from EAS over their FE programs based on CNC word scores. CONCLUSIONS: Whether newly implanted or long-term CI users, children with residual hearing after CI surgery can benefit from EAS. Cochlear implantation with EAS fitting is a viable option for children with HAs who have residual hearing but have insufficient access to high-frequency sounds and poor speech perception.