Improved Postoperative Speech Recognition and Processor Use With Early Cochlear Implant Activation.

OBJECTIVE: To report speech recognition outcomes and processor use based on timing of cochlear implant (CI) activation. STUDY DESIGN: Retrospective cohort. SETTING: Tertiary referral center. PATIENTS: A total of 604 adult CI recipients from October 2011 to March 2022, stratified by timing of CI activation (group 1: ≤10 d, n = 47; group 2: >10 d, n = 557). MAIN OUTCOME MEASURES: Average daily processor use; Consonant-Nucleus-Consonant (CNC) and Arizona Biomedical (AzBio) in quiet at 1-, 3-, 6-, and 12-month visits; time to peak performance. RESULTS: The groups did not differ in sex ( p = 0.887), age at CI ( p = 0.109), preoperative CNC ( p = 0.070), or preoperative AzBio in quiet ( p = 0.113). Group 1 had higher median daily processor use than group 2 at the 1-month visit (12.3 versus 10.7 h/d, p = 0.017), with no significant differences at 3, 6, and 12 months. The early activation group had superior median CNC performance at 3 months (56% versus 46%, p = 0.007) and 12 months (60% versus 52%, p = 0.044). Similarly, the early activation group had superior median AzBio in quiet performance at 3 months (72% versus 59%, p = 0.008) and 12 months (75% versus 68%, p = 0.049). Both groups were equivalent in time to peak performance for CNC and AzBio. Earlier CI activation was significantly correlated with higher average daily processor use at all follow-up intervals. CONCLUSION: CI activation within 10 days of surgery is associated with increased early device usage and superior speech recognition at both early and late follow-up visits. Timing of activation and device usage are modifiable factors that can help optimize postoperative outcomes in the CI population.

Comprehensive behavioral and physiologic assessment of peripheral and central auditory function in individuals with mild traumatic brain injury.

Auditory complaints are frequently reported by individuals with mild traumatic brain injury (mTBI) yet remain difficult to detect in the absence of clinically significant hearing loss. This highlights a growing need to identify sensitive indices of auditory-related mTBI pathophysiology beyond pure-tone thresholds for improved hearing healthcare diagnosis and treatment. Given the heterogeneity of mTBI etiology and the diverse peripheral and central processes required for normal auditory function, the present study sought to determine the audiologic assessments sensitive to mTBI pathophysiology at the group level using a well-rounded test battery of both peripheral and central auditory system function. This test battery included pure-tone detection thresholds, word understanding in quiet, sentence understanding in noise, distortion product otoacoustic emissions (DPOAEs), middle-ear muscle reflexes (MEMRs), and auditory evoked potentials (AEPs), including auditory brainstem responses (ABRs), middle latency responses (MLRs), and late latency responses (LLRs). Each participant also received magnetic resonance imaging (MRI). Compared to the control group, we found that individuals with mTBI had reduced DPOAE amplitudes that revealed a compound effect of age, elevated MEMR thresholds for an ipsilateral broadband noise elicitor, longer ABR Wave I latencies for click and 4 kHz tone burst elicitors, longer ABR Wave III latencies for 4 kHz tone bursts, larger MLR Na and Nb amplitudes, smaller MLR Pb amplitudes, longer MLR Pa latencies, and smaller LLR N1 amplitudes for older individuals with mTBI. Further, mTBI individuals with combined hearing difficulty and noise sensitivity had a greater number of deficits on thalamic and cortical AEP measures compared to those with only one/no self-reported auditory symptoms. This finding was corroborated with MRI, which revealed significant structural differences in the auditory cortical areas of mTBI participants who reported combined hearing difficulty and noise sensitivity, including an enlargement of left transverse temporal gyrus (TTG) and bilateral planum polare (PP). These findings highlight the need for continued investigations toward identifying individualized audiologic assessments and treatments that are sensitive to mTBI pathophysiology.

Cochlear Implant Upper Stimulation Levels: eSRT vs. Loudness Scaling.

OBJECTIVE: To assess the difference in speech recognition and sound quality between programming upper stimulation levels using behavioral measures (loudness scaling) and electrically evoked stapedial reflex thresholds (eSRTs). STUDY DESIGN: Double-blinded acute comparison study. SETTING: Cochlear implant (CI) program at a tertiary medical center. PATIENTS: Eighteen adult (mean age = 60 years) CI users and 20 ears. MAIN OUTCOME MEASURES: Speech recognition scores and sound quality ratings. RESULTS: Mean word and sentence in noise recognition scores were 8 and 9 percentage points higher, respectively, for the eSRT-based map. The sound quality rating was 1.4 points higher for the eSRT-based map. Sixteen out of 20 participants preferred the eSRT-based map. CONCLUSIONS: Study results show significantly higher speech recognition and more favorable sound quality using an eSRT-based map compared with a loudness-scaling map using a double-blinded testing approach. Additionally, results may be understated as 18 of 20 ears had eSRTs measured before study enrollment. Results underscore the importance of incorporating eSRTs into standard clinical practice to promote best outcomes for CI recipients.

Development of an Optimized Protocol for Cochlear Implant Care to Increase Cochlear Implant Access.

OBJECTIVE: To develop an evidence-based protocol for audiology-based, cochlear implant (CI) programming in the first year after activation. STUDY DESIGN: Retrospective case review. SETTING: CI program at a tertiary medical center. PATIENTS: One-hundred seventy-one patients (178 ears; mean age at implantation, 62.3 yr; 44.4% female) implanted between 2016 and 2021 with postlingual onset of deafness and no history of CI revision surgery. Patients included here had confirmed CI programming optimization based on CI-aided thresholds in the 20- to 30-dB-HL range as well as upper stimulation levels guided by electrically evoked stapedial reflex thresholds. MAIN OUTCOME MEASURES: Consonant-nucleus-consonant monosyllabic word recognition scores in the CI-alone and bilateral best-aided conditions at five time points: preoperative evaluation, and 1, 3, 6, and 12 months after activation. RESULTS: For both the CI-alone and bilateral best-aided conditions, consonant-nucleus-consonant word recognition significantly improved from preoperative evaluation to all postactivation time points. For the CI-alone condition, no significant differences were observed between 3 and 6 months, or from 6 to 12 months after activation. In contrast, for the bilateral best-aided condition, significant differences were observed between 1 and 3 months, and 3 and 6 months, but no difference in scores between 6 and 12 months. CONCLUSIONS: Based on the current data set and associated analyses, CI centers programming adult patients could eliminate either the 3- or 6-month visit from their clinical follow-up schedule if patient mapping of lower and upper stimulation levels is validated via CI-aided audiometric thresholds and electrically evoked stapedial reflex thresholds, respectively.

Sound Level Changes the Auditory Cortical Activation Detected with Functional Near-Infrared Spectroscopy.

BACKGROUND: Functional near-infrared spectroscopy (fNIRS) is a viable non-invasive technique for functional neuroimaging in the cochlear implant (CI) population; however, the effects of acoustic stimulus features on the fNIRS signal have not been thoroughly examined. This study examined the effect of stimulus level on fNIRS responses in adults with normal hearing or bilateral CIs. We hypothesized that fNIRS responses would correlate with both stimulus level and subjective loudness ratings, but that the correlation would be weaker with CIs due to the compression of acoustic input to electric output. METHODS: Thirteen adults with bilateral CIs and 16 with normal hearing (NH) completed the study. Signal-correlated noise, a speech-shaped noise modulated by the temporal envelope of speech stimuli, was used to determine the effect of stimulus level in an unintelligible speech-like stimulus between the range of soft to loud speech. Cortical activity in the left hemisphere was recorded. RESULTS: Results indicated a positive correlation of cortical activation in the left superior temporal gyrus with stimulus level in both NH and CI listeners with an additional correlation between cortical activity and perceived loudness for the CI group. The results are consistent with the literature and our hypothesis. CONCLUSIONS: These results support the potential of fNIRS to examine auditory stimulus level effects at a group level and the importance of controlling for stimulus level and loudness in speech recognition studies. Further research is needed to better understand cortical activation patterns for speech recognition as a function of both stimulus presentation level and perceived loudness.

Early Datalogging Predicts Cochlear Implant Performance: Building a Recommendation for Daily Device Usage.

OBJECTIVE: To quantify the effect of datalogging on speech recognition scores and time to achievement for a "benchmark" level of performance within the first year, and to provide a data-driven recommendation for minimum daily cochlear implant (CI) device usage to better guide patient counseling and future outcomes. STUDY DESIGN: Retrospective cohort. SETTING: Tertiary referral center. PATIENTS: Three hundred thirty-seven adult CI patients with data logging and speech recognition outcome data who were implanted between August 2015 and August 2020. MAIN OUTCOME MEASURES: Processor datalogging, speech recognition scores, achievement of "benchmark speech recognition performance" defined as 80% of the median score for speech recognition outcomes at our institution. RESULTS: The 1-month datalogging measure correlated positively with word and sentences scores at 1, 3, 6, and 12 months postactivation. Compared with age, sex, and preoperative performance, datalogging was the largest predictive factor of benchmark achievement on multivariate analysis. Each hour/day increase of device usage at 1 month resulted in a higher likelihood of achieving benchmark consonant-nucleus-consonant and AzBio scores within the first year (odds ratio = 1.21, p < 0.001) as well as earlier benchmark achievement. Receiver operating characteristic curve analysis identified the optimal data logging threshold at an average of 12 hours/day. CONCLUSIONS: Early CI device usage, as measured by 1-month datalogging, predicts benchmark speech recognition achievement in adults. Datalogging is an important predictor of CI performance within the first year postimplantation. These data support the recommended daily CI processor utilization of at least 12 hours/day to achieve optimal speech recognition performance for most patients.

Cholinergic modulation of sensory perception and plasticity.

Sensory systems are highly plastic, but the mechanisms of sensory plasticity remain unclear. People with vision or hearing loss demonstrate significant neural network reorganization that promotes adaptive changes in other sensory modalities as well as in their ability to combine information across the different senses (i.e., multisensory integration. Furthermore, sensory network remodeling is necessary for sensory restoration after a period of sensory deprivation. Acetylcholine is a powerful regulator of sensory plasticity, and studies suggest that cholinergic medications may improve visual and auditory abilities by facilitating sensory network plasticity. There are currently no approved therapeutics for sensory loss that target neuroplasticity. This review explores the systems-level effects of cholinergic signaling on human visual and auditory perception, with a focus on functional performance, sensory disorders, and neural activity. Understanding the role of acetylcholine in sensory plasticity will be essential for developing targeted treatments for sensory restoration.

The Impact of Daily Processor Use on Adult Cochlear Implant Outcomes: Reexamining the Roles of Duration of Deafness and Age at Implantation.

OBJECTIVE: To quantify the roles and relationships between age at implantation, duration of deafness (DoD), and daily processor use via data logging on speech recognition outcomes for postlingually deafened adults with cochlear implants. STUDY DESIGN: Retrospective case review. SETTING: Cochlear implant (CI) program at a tertiary medical center. PATIENTS: Six-hundred fourteen postlingually deafened adult ears with CIs (mean age, 63 yr; 44% female) were included. MAIN OUTCOME MEASURES: A stepwise multiple regression analysis was completed to investigate the combined effects of age, DoD, and daily processor use on CI-aided speech recognition (Consonant-Nucleus-Consonant monosyllables and AzBio sentences). RESULTS: Results indicated that only daily processor use was significantly related to Consonant-Nucleus-Consonant word scores ( R2 = 0.194, p < 0.001) and AzBio in quiet scores ( R2 = 0.198, p < 0.001), whereas neither age nor DoD was significantly related. In addition, there was no significant relationship between daily processor use, age at implantation, or DoD and AzBio sentences in noise ( R2 = 0.026, p = 0.005). CONCLUSIONS: Considering the clinical factors of age at implantation, DoD, and daily processor use, only daily processor use significantly predicted the ~20% of variance in postoperative outcomes (CI-aided speech recognition) accounted for by these clinical factors.

Visually biased Perception in Cochlear Implant Users: A Study of the McGurk and Sound-Induced Flash Illusions.

The reduction in spectral resolution by cochlear implants oftentimes requires complementary visual speech cues to facilitate understanding. Despite substantial clinical characterization of auditory-only speech measures, relatively little is known about the audiovisual (AV) integrative abilities that most cochlear implant (CI) users rely on for daily speech comprehension. In this study, we tested AV integration in 63 CI users and 69 normal-hearing (NH) controls using the McGurk and sound-induced flash illusions. To our knowledge, this study is the largest to-date measuring the McGurk effect in this population and the first that tests the sound-induced flash illusion (SIFI). When presented with conflicting AV speech stimuli (i.e., the phoneme "ba" dubbed onto the viseme "ga"), we found that 55 CI users (87%) reported a fused percept of "da" or "tha" on at least one trial. After applying an error correction based on unisensory responses, we found that among those susceptible to the illusion, CI users experienced lower fusion than controls-a result that was concordant with results from the SIFI where the pairing of a single circle flashing on the screen with multiple beeps resulted in fewer illusory flashes for CI users. While illusion perception in these two tasks appears to be uncorrelated among CI users, we identified a negative correlation in the NH group. Because neither illusion appears to provide further explanation of variability in CI outcome measures, further research is needed to determine how these findings relate to CI users' speech understanding, particularly in ecological listening conditions that are naturally multisensory.

Effects of the Number of Channels and Channel Stimulation Rate on Speech Recognition and Sound Quality Using Precurved Electrode Arrays.

PURPOSE: This study investigated the relationship between the number of active electrodes, channel stimulation rate, and their interaction on speech recognition and sound quality measures while controlling for electrode placement. Cochlear implant (CI) recipients with precurved electrode arrays placed entirely within scala tympani and closer to the modiolus were hypothesized to be able to utilize more channels and possibly higher stimulation rates to achieve better speech recognition performance and sound quality ratings than recipients in previous studies. METHOD: Participants included seven postlingually deafened adult CI recipients with Advanced Bionics Mid-Scala electrode arrays confirmed to be entirely within scala tympani using postoperative computerized tomography. Twelve conditions were tested using four, eight, 12, and 16 electrodes and channel stimulation rates of 600 pulse per second (pps), 1,200 pps, and each participant's maximum allowable rate (1,245-4,800 pps). Measures of speech recognition and sound quality were acutely assessed. RESULTS: For the effect of channels, results showed no significant improvements beyond eight channels for all measures. For the effect of channel stimulation rate, results showed no significant improvements with higher rates, suggesting that 600 pps was sufficient for maximum speech recognition performance and sound quality ratings. However, across all conditions, there was a significant relationship between mean electrode-to-modiolus distance and all measures, suggesting that a lower mean electrode-to-modiolus distance was correlated with higher speech recognition scores and sound quality ratings. CONCLUSION: These findings suggest that even well-placed precurved electrode array recipients may not be able to take advantage of more than eight channels or higher channel stimulation rates (> 600 pps), but that closer electrode array placement to the modiolus correlates with better outcomes for these recipients.

Integration of fundamental frequency and voice-onset-time to voicing categorization: Listeners with normal hearing and bimodal hearing configurations.

This study investigates the integration of word-initial fundamental frequency (F0) and voice-onset-time (VOT) in stop voicing categorization for adult listeners with normal hearing (NH) and unilateral cochlear implant (CI) recipients utilizing a bimodal hearing configuration [CI + contralateral hearing aid (HA)]. Categorization was assessed for ten adults with NH and ten adult bimodal listeners, using synthesized consonant stimuli interpolating between /ba/ and /pa/ exemplars with five-step VOT and F0 conditions. All participants demonstrated the expected categorization pattern by reporting /ba/ for shorter VOTs and /pa/ for longer VOTs, with NH listeners showing more use of VOT as a voicing cue than CI listeners in general. When VOT becomes ambiguous between voiced and voiceless stops, NH users make more use of F0 as a cue to voicing than CI listeners, and CI listeners showed greater utilization of initial F0 during voicing identification in their bimodal (CI + HA) condition than in the CI-alone condition. The results demonstrate the adjunctive benefit of acoustic hearing from the non-implanted ear for listening conditions involving spectrotemporally complex stimuli. This finding may lead to the development of a clinically feasible perceptual weighting task that could inform clinicians about bimodal efficacy and the risk-benefit profile associated with bilateral CI recommendation.

Cochlear Implants for Single-Sided Deafness: Quality of Life, Daily Usage, and Duration of Deafness.

OBJECTIVE: To report our experience for adults undergoing cochlear implantation (CI) for single-sided deafness (SSD). METHODS: This is a retrospective case series for adults with SSD who underwent CI between January 2013 and May 2021 at our institution. CNC and AzBio speech recognition scores, Tinnitus Handicap Inventory (THI), Speech, Spatial, and Qualities of Hearing Scale (SSQ12), datalogging, and the Cochlear Implant Quality of Life (CIQOL)-10 Global measure were utilized. RESULTS: Sixty-six adults underwent CI for SSD (median 51.3 years, range 20.0-74.3 years), and 57 (86.4%) remained device users at last follow-up. Compared to pre-operative performance, device users demonstrated significant improvement in speech recognition scores and achieved peak performance at six months post-activation for CNC (8.0% increased to 45.6%, p < 0.0001) and AzBio in quiet (12.2% increased to 59.5%, p < 0.0001). THI was decreased at 6 months post-implantation (58.1-14.6, p < 0.0001), with 77% of patients reporting improved or resolved tinnitus. Patients demonstrated improved SSQ12 scores as well as the disease-specific CIQOL-10 Global questionnaire. Duration of deafness was not associated with significant differences in speech recognition performance. Average daily wear time was positively associated with CNC and AzBio scores as well as post-operative CIQOL-10 scores. CONCLUSIONS: Herein we present the largest cohort of adult CI recipients with SSD with data on speech recognition scores, tinnitus measures, and SSQ12. Novel insights regarding the correlation of datalogging, duration of deafness, and CI-specific quality of life (CIQOL-10) metrics are discussed. Data continue to support CI as an efficacious treatment option for SSD. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:2362-2370, 2023.

The Effects of Middle-ear Stiffness on the Auditory Brainstem Neural Encoding of Phase.

The middle-ear system relies on a balance of mass and stiffness characteristics for transmitting sound from the external environment to the cochlea and auditory neural pathway. Phase is one aspect of sound that, when transmitted and encoded by both ears, contributes to binaural cue sensitivity and spatial hearing. The study aims were (i) to investigate the effects of middle-ear stiffness on the auditory brainstem neural encoding of phase in human adults with normal pure-tone thresholds and (ii) to investigate the relationships between middle-ear stiffness-induced changes in wideband acoustic immittance and neural encoding of phase. The auditory brainstem neural encoding of phase was measured using the auditory steady-state response (ASSR) with and without middle-ear stiffness elicited via contralateral activation of the middle-ear muscle reflex (MEMR). Middle-ear stiffness was quantified using a wideband acoustic immittance assay of acoustic absorbance. Statistical analyses demonstrated decreased ASSR phase lag and decreased acoustic absorbance with contralateral activation of the MEMR, consistent with increased middle-ear stiffness changing the auditory brainstem neural encoding of phase. There were no statistically significant correlations between stiffness-induced changes in wideband acoustic absorbance and ASSR phase. The findings of this study may have important implications for understanding binaural cue sensitivity and horizontal plane sound localization in audiologic and otologic clinical populations that demonstrate changes in middle-ear stiffness, including cochlear implant recipients who use combined electric and binaural acoustic hearing and otosclerosis patients.

Guidelines for Best Practice in the Audiological Management of Adults Using Bimodal Hearing Configurations.

Clinics are treating a growing number of patients with greater amounts of residual hearing. These patients often benefit from a bimodal hearing configuration in which acoustic input from a hearing aid on 1 ear is combined with electrical stimulation from a cochlear implant on the other ear. The current guidelines aim to review the literature and provide best practice recommendations for the evaluation and treatment of individuals with bilateral sensorineural hearing loss who may benefit from bimodal hearing configurations. Specifically, the guidelines review: benefits of bimodal listening, preoperative and postoperative cochlear implant evaluation and programming, bimodal hearing aid fitting, contralateral routing of signal considerations, bimodal treatment for tinnitus, and aural rehabilitation recommendations.

Speech recognition as a function of the number of channels for pediatric cochlear implant recipients.

This study investigated the number of channels required for asymptotic speech recognition for ten pediatric cochlear implant (CI) recipients with precurved electrode arrays. Programs with 4-22 active electrodes were used to assess word and sentence recognition in noise. Children demonstrated significant performance gains up to 12 electrodes for continuous interleaved sampling (CIS) and up to 22 channels with 16 maxima. These data are consistent with the latest adult CI studies demonstrating that modern CI recipients have access to more than 8 independent channels and that both adults and children exhibit performance gains up to 22 channels.

A Five-Year Update on the Profile of Adults Undergoing Cochlear Implant Evaluation and Surgery-Are We Doing Better?

OBJECTIVE: To characterize the influence of expanding indications on the profile of adults undergoing cochlear implantation (CI) at a high-volume CI center. STUDY DESIGN: Retrospective review. SETTING: Tertiary referral center. PATIENTS: 774 adults undergoing CI evaluation from August 2015 to August 2020. MAIN OUTCOME MEASURES: Demographics; audiometry; speech recognition; speech, spatial, and qualities of hearing scale (SSQ-12). RESULTS: Of 745 (96.3%) patients qualifying for implantation, 642 (86.6%) pursued surgery. Median age at evaluation was 69 years; 56.3% were men; 88.2% were Caucasian. Median distance to our center was 95 miles. The majority (51.8%) had public insurance (Medicare, Medicaid), followed by private (47.8%) and military (0.4%). Mean PTA, CNC, and AzBio in quiet and noise for the ear to be implanted were 85.2 dB HL, 15.0%, and 19.2% and 3.5%, respectively. Hybrid/EAS criteria were met by 138 (18.5%) CI candidates, and 436 (77.0%) unilateral CI recipients had aidable contralateral hearing for bimodal hearing configurations. Younger age (odds ratio [OR], 0.96; 95% confidence interval, 0.93-0.99) and non-Caucasian race (OR, 6.95; 95% confidence interval, 3.22-14.98) predicted candidacy. Likelihood of surgery increased for Caucasian (OR, 8.08; 95% confidence interval, 4.85-13.47) and married (OR, 2.28; 95% confidence interval, 1.50-3.47) patients and decreased for those with public insurance (OR, 0.45; 95% confidence interval, 0.29-0.69). A lower SSQ-12 score predicted both candidacy and surgery. CONCLUSION: Despite expansions in criteria, speech understanding remained extremely low at CI evaluation. Younger age and non-Caucasian race predicted candidacy, and Caucasian, married patients with private insurance and lower SSQ scores were more likely to pursue surgery.

Cochlear implant spectral bandwidth for optimizing electric and acoustic stimulation (EAS).

Cochlear implantation with acoustic hearing preservation is becoming increasingly prevalent allowing cochlear implant (CI) users to combine electric and acoustic stimulation (EAS) in the implanted ears. Despite a growing EAS population, our field does not have definitive guidance regarding EAS technology optimization and the majority of previous studies investigating hearing aid (HA) and cochlear implant (CI) programming for EAS listeners have been mixed. Thus, the purpose of this exploratory study was to explore the effects of various EAS crossover frequencies-defined as the low-frequency (LF) CI cutoff-relative to the underlying spiral ganglion (SG) characteristic frequency associated with the most distal or apical electrode in the array. Speech recognition in semi-diffuse noise and subjective estimates of listening difficulty were measured for 15 adult CI recipients with acoustic hearing preservation in three listening conditions: 1) CI-alone, 2) bimodal (CI+HA), and best-aided EAS (CIHA+HA). The results showed no effect of LF CI cutoff for any of the three listening conditions such that there was no trend for increased performance or less subjective listening difficulty across LF CI cutoffs, referenced to underlying SG-place frequency. Consistent with past studies, the current results were also consistent with significant speech recognition and subject listening difficulty benefits for both bimodal (CI+HA) and best-aided EAS (CIHA+HA) as compared to CI-alone listening as well as significant additional benefits for best-aided EAS (CIHA+HA) compared to bimodal hearing (CI+HA). Future studies are necessary to investigate the efficacy of SG-place-based fittings for i) large samples of experienced EAS listeners for whom perceptual adaptation has occurred to the frequency mismatch provided by standard CI frequency allocations, and ii) EAS users at or close to CI activation as place-based approaches may ultimately yield greater outcomes, particularly for newly activated CI users for whom SG-place-based approaches may afford a steeper trajectory to performance asymptote.

Speech recognition as a function of the number of channels for Mid-Scala electrode array recipients.

This study investigated the number of channels needed for maximum speech understanding and sound quality in 15 adult cochlear implant (CI) recipients with Advanced Bionics (AB) Mid-Scala electrode arrays completely within scala tympani. In experiment I, CI programs used a continuous interleaved sampling (CIS)-based strategy and 4-16 active electrodes. In experiment II, CI programs used an n-of-m strategy featuring 16 active electrodes with either 8- or 12-maxima. Speech understanding and sound quality measures were assessed. For CIS programs, participants demonstrated performance gains using up to 4-10 electrodes on speech measures and sound quality ratings. For n-of-m programs, there was no significant effect of maxima, suggesting 8-maxima is sufficient for this sample's maximum performance and sound quality. These results are largely consistent with previous studies using straight electrode arrays [e.g., Fishman, Shannon, and Slattery (1997). J. Speech Lang. Hear. Res. 40, 1201-1215; Friesen, Shannon, Baskent, and Wang (2001). J. Acoust. Soc. Am. 110, 1150-1163; Shannon, Cruz, and Galvin (2011). Audiol. Neurotol. 16, 113-123; Berg, Noble, Dawant, Dwyer, Labadie, and Gifford (2020). J. Acoust. Soc. Am. 147, 3646-3656] and in contrast with recent studies looking at cochlear precurved electrode arrays [e.g., Croghan, Duran, and Smith (2017). J. Acoust. Soc. Am. 142, EL537-EL543; Berg, Noble, Dawant, Dwuer, Labadie, and Gifford (2019b). J. Acoust. Soc. Am. 145, 1556-1564], which found continuous improvements up to 16 independent channels. These findings suggest that Mid-Scala electrode array recipients demonstrate similar channel independence to straight electrode arrays rather than other manufacturer's precurved electrode arrays.

Functional localization of audiovisual speech using near infrared spectroscopy.

Visual cues are especially vital for hearing impaired individuals such as cochlear implant (CI) users to understand speech in noise. Functional Near Infrared Spectroscopy (fNIRS) is a light-based imaging technology that is ideally suited for measuring the brain activity of CI users due to its compatibility with both the ferromagnetic and electrical components of these implants. In a preliminary step toward better elucidating the behavioral and neural correlates of audiovisual (AV) speech integration in CI users, we designed a speech-in-noise task and measured the extent to which 24 normal hearing individuals could integrate the audio of spoken monosyllabic words with the corresponding visual signals of a female speaker. In our behavioral task, we found that audiovisual pairings provided average improvements of 103% and 197% over auditory-alone listening conditions in -6 and -9 dB signal-to-noise ratios consisting of multi-talker background noise. In an fNIRS task using similar stimuli, we measured activity during auditory-only listening, visual-only lipreading, and AV listening conditions. We identified cortical activity in all three conditions over regions of middle and superior temporal cortex typically associated with speech processing and audiovisual integration. In addition, three channels active during the lipreading condition showed uncorrected correlations associated with behavioral measures of audiovisual gain as well as with the McGurk effect. Further work focusing primarily on the regions of interest identified in this study could test how AV speech integration may differ for CI users who rely on this mechanism for daily communication.

HiRes Ultra Series Recall: Failure Rates and Revision Speech Recognition Outcomes.

OBJECTIVE: To report Advanced Bionics (AB) Ultra (V1) and Ultra 3D (V1) cochlear implant (CI) electrode failures and revision speech recognition outcomes for patients at a large CI program. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. PATIENTS: Patients receiving Ultra (V1) or Ultra 3D (V1) devices as of September 21, 2021. MAIN OUTCOME MEASURES: Failure rate, revision surgery, speech recognition scores. RESULTS: To data, 65 (21.1%) of the 308 implanted devices are known failures, with 63 (20.5%) associated with the recent voluntary field corrective action (FCA). Average time to failure was 2.2 ± 1.1 years. Fifty-two patients (82.5%) elected for revision surgery. Among adults, immediate prerevision scores demonstrated a significant decrease from best-achieved scores with the faulty implant, with mean difference of -15.2% (p = 0.0115) for consonant-nucleus-consonant (CNC) and -27.3% (p < 0.0001) for AzBio in quiet. By 3 months postactivation of the revised device, CNC (p = 0.9766) and AzBio in quiet (p = 0.9501) scores were not significantly different than best prerevision scores. Overall, 15 of 19 patients regained or improved their best prerevision CNC score. The current trajectory for FCA device failures is approximately 6% per year. CONCLUSION: Compared to manufacturer reporting, a high number of patients experienced hard failures of the Ultra (V1) and Ultra 3D (V1) devices. Early identification of failures is possibly because of the diligent use of electrical field imaging testing. Most patients affected by the FCA regain or exceed their prefailure speech recognition score as soon as 3 months after revision surgery.