Bilateral Cochlear Implants Research Articles

Effects of frequency-to-place mismatch in children listening to simualted unilateral and bilateral cochlear implant configurations

Binaural cues are important for spatial speech recognition. While binaural cues can be partly restored by bilateral cochlear implants or a unilateral cochlear implant in patients with single-sided deafness, the benefits may be limited by frequency-to-place mismatch in both cases. Previous studies reported worse recognition of spatially separated speech as frequency-to-place mismatch increased in typical-hearing adults listening to acoustic simulations of bilateral cochlear implants (Thomas et al., 2022). This work also revealed that children were more sensitive to the spectral degradation and less able to use spatial cues for spatial speech recognition. The present study investigates the effects of frequency-to-place mismatch on binaural fusion in typical hearing children (7–9 years old) listening to acoustic simulations of bi- and unilateral cochlear implant configurations. The stimuli in the left ear were either unprocessed or processed by a 16-channel sinewave vocoder with a fixed insertion depth while the stimuli in the right ear were processed by 16-channel sinewave vocoders with varying insertion depth. Speech recognition threshold results from N = 10 children show an effect of interaural insertion depth mismatch upon speech recognition thresholds, with no differences by age. Comparisons with adult data will likewise be reported.

Perception of emotional music by children with cochlear implants reveals developmental plasticity

Cochlear implants provide poor access to the frequency components needed to accurately identify emotional music and speech. Nonetheless, a series of studies revealed that children with cochlear implants develop unique strategies to identify emotion in music. Although musical changes were difficult for them to detect, children with cochlear implants responded most accurately to rhythmic changes and also relied mainly on temporal information to judge whether music was happy or sad. By contrast, mode (frequency) information dominated perception of musical emotion in typically developing children and was used more clearly by bimodal device users (cochlear implant in one ear with acoustic hearing in the other) than children with bilateral deafness using unilateral or bilateral cochlear implants. Mode became the more dominant cue with increasing residual hearing in the non-implanted ear. Children with unilateral cochlear implants showed prolonged response times relative to a control group of normal hearing peers while judging whether music was happy or sad. Response times in children with bimodal devices and bilateral cochlear implants were more similar to controls. Together, these results demonstrate development of novel strategies for music listening and perception of emotion in music based on available cues in children with cochlear implants and suggest that these strategies require cognitive resource.

Lateralization of interaural time differences with mixed rates of stimulation in bilateral cochlear implant listeners.

While listeners with bilateral cochlear implants (BiCIs) are able to access information in both ears, they still struggle to perform well on spatial hearing tasks when compared to normal hearing listeners. This performance gap could be attributed to the high stimulation rates used for speech representation in clinical processors. Prior work has shown that spatial cues, such as interaural time differences (ITDs), are best conveyed at low rates. Further, BiCI listeners are sensitive to ITDs with a mixture of high and low rates. However, it remains unclear whether mixed-rate stimuli are perceived as unitary percepts and spatially mapped to intracranial locations. Here, electrical pulse trains were presented on five, interaurally pitch-matched electrode pairs using research processors, at either uniformly high rates, low rates, or mixed rates. Eight post-lingually deafened adults were tested on perceived intracranial lateralization of ITDs ranging from 50 to 1600 μs. Extent of lateralization depended on the location of low-rate stimulation along the electrode array: greatest in the low- and mixed-rate configurations, and smallest in the high-rate configuration. All but one listener perceived a unitary auditory object. These findings suggest that a mixed-rate processing strategy can result in good lateralization and convey a unitary auditory object with ITDs.

A longitudinal study of cortical auditory maturation and implications of the short inter-implant delay in children with bilateral sequential cochlear implants.

This longitudinal study aimed to investigate the maturational development of P1 latency and the effects of a short inter-implant delay in children who received bilateral sequential cochlear implants. Fourteen children (first CI mean age: 1.4±0.4 years and Second CI mean age: 3.3±0.5 years) who had received sequential bilateral cochlear implants during the sensitive period for auditory maturation participated in our study. The speech-evoked cortical P1 response was recorded after the activation of the second CI at four intervals (implant activation, 3 months, 6 months, 12 months) under three listening conditions (first CI, second CI, binaural). Our results showed that the P1 latencies of the second CI reached normative values within 3 months, but did not reach the P1 latency of the first CI until 12 months. We found a strong negative correlation between the inter-implant delay and the P1 latencies of the second CI when the second CI was activated. Changes in cortical auditory responses over time resulted in normal auditory maturation in children with sequential bilateral cochlear implants during the sensitive period. The results also provide evidence that the timing of auditory experience in the first ear during the sensitive period may influence the speed of compensation in children receiving sequential cochlear implants.

Impact of hearing impairment and cochlear implantation on productivity and social well-being in a professionally active but severely hearing-impaired group: protocol of the ‘Hear again, work again’ longitudinal prospective cohort study

IntroductionSevere hearing loss is a sensory deficit with considerable impact on the patient’s daily life and on society. Previous research has established occupational obstacles in professionally active patients with hearing...

The effects of background noise and reverberation on speech perception in cochlear implant users

Indoor noise and reverberation interfere with speech understanding for listeners. Degradation in cochlear implant (CI) processing presents additional challenges for CI users to understand noisy and reverberant speech. Inthis study, we investigated the effect of adverse acoustics on speech perception on three tasks that changed in difficulty and increasing need for top-down processing: (1) word recall, (2) sentence recognition, and (3) conversation comprehension. Each task was tested in five conditions that varied in combinations of adverse acoustics from reverberation (i.e., anechoic, 0.4s RT, vs 1.2s RT) and noise (i.e., quiet versus Speech-shaped-noise at −3dB). We compared performances from normal-hearing (NH) listeners and bilateral CI users between 15 and 25 years old. Preliminary results show that while NH listeners may have some tolerance for speech perception under adverse acoustics, CI users experienced more graded performance deterioration with increasing reverberation and noise. Moreover, we observed task-dependent performance change across adverse acoustic conditions in both NH and CI listeners: While some context (i.e., sentences) may help speech perception, comprehension based on pragmatic language processing (i.e., conversations) is vulnerable under difficult listening situations. These results provide insights on how NH and CI listeners differ in their access to top-down processing in real-world speech perception.

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.

Experience with 2D Exoscope System for Bilateral Simultaneous Cochlear Implant Surgery in the Era of the COVID-19 Pandemic.

We report the first case series utilizing the exoscope exclusively for bilateral simultaneous cochlear implant surgery and discuss the advantages, disadvantages, as well as surgical outcomes in the Covid-19 era. The VITOM® 2D is compatible with enhanced PPE and draping techniques which can improve safety while providing comparable surgical outcomes.

Early cochlear implantation in prelingual profound hearing loss in Italy, analyzed by means of a social media survey.

To assess newborn hearing screening (NHS) impact on timing of cochlear implant (CI) surgery of patients with prelingual bilateral profound hearing impairment (BPHI), in order to evaluate whether the NHS ultimately serves the needs of the target population in Italy. An online questionnaire was created to survey subjects affected by prelingual BPHL born between 1990 and 2018. Questions focused on age at BPHI diagnosis, first and second CI surgery (if performed), and the region in which the surgery was performed. The survey was distributed to potential participants via social media communities used by hearing impaired people or their family members for sharing advice and offering support. Responses were analyzed using descriptive statistics. Among the 318 respondents who completed the questionnaire, 276 (87%) reported having chosen CI surgery, 2/3 of them bilaterally. In the vast majority (97%) of cases the CI is used on a daily basis. Most of the people residing in the center (65%) and southern Italy (71%) had to move from their region of residence to perform the surgery. Late CI surgery was associated with failure to perform NHS (p = 0.007), birth before 2011 (p = 0.009), definitive diagnosis of BPHI after 6months of life (p = 0.002), and progressive hearing impairment (p < 0.001). The worldwide scientific approval of the NHS as the current best opportunity for early diagnosis and CI treatment for prelingual BPHI is confirmed by what patients and families reported via the online questionnaire used for this study. In recent years, early bilateral cochlear implantation has become increasingly available in Italy, but late diagnosis, progressive hearing loss, failure to perform the NHS and lack of follow-up are still open questions. A large proportion of families had to move from the region of residence to have their child undergo CI surgery, revealing inequalities in terms of geographical disparities. Social media has proved to be a valuable, fast and inexpensive tool for gathering information on the effectiveness of health prevention programs, involving a large sample of individuals in a short amount of time.

Speech Perception and Sound Localization Skills in Inner Ear Malformations: Children With Incomplete Partition Type-II.

The present study aimed to evaluate binaural auditory skills in bimodal and bilateral pediatric cochlear implant (CI) users with incomplete partition type-II (IP-II) and to reveal the effect of IP-II on performance by comparing the results to pediatric CI users with normal cochlear morphology. Cross-sectional study. Tertiary referral center. Forty-one CI users (mean age 8.8 ± 1.9) were grouped as bimodal (BIM-IP) and bilateral (BIL-IP) users with IP-II; bimodal (BIM-N) and bilateral (BIL-N) users with normal cochlear anatomy. Speech perception in noise and sound localization skills were compared under 2conditions; binaural (bilateral or bimodal) and monaural (first CI alone). BIM-IP and BIL-IP showed no performance difference in binaural tasks. The BIM-N group showed remarkably poor performance in comparison to the groups of BIL-IP (p = .007), BIM-IP (p < .001), and BIL-N (p = .004) in terms of speech-in-noise skills. In sound localization abilities, similar significant differences were found between the group of BIM-N and the groups of BIL-IP (p = .001), BIM-IP (p < .001), and BIL-N (p = .004). All groups showed statistically significant improvements in binaural condition on both tasks (p < .05). We revealed that bilateral and bimodal pediatric CI users with IP-II benefitted from implantation as much as bilateral users with normal anatomy. Differences in residual hearing between groups may explain the poor performance of bimodal users with normal cochlear morphology. To the best of our knowledge, it is the first study to unveil binaural performance characteristics in children diagnosed with a specific inner ear malformation subgroup.

Effect of interaural electrode insertion depth difference and independent band selection on sentence recognition in noise and spatial release from masking in simulated bilateral cochlear implant listening

PurposeInter-aural insertion depth difference (IEDD) in bilateral cochlear implant (BiCI) with continuous interleaved sampling (CIS) processing is known to reduce the recognition of speech in noise and spatial release from masking (SRM). However, the independent channel selection in the ‘n-of-m’ sound coding strategy might have a different effect on speech recognition and SRM when compared to the effects of IEDD in CIS-based findings. This study aimed to investigate the effect of bilateral ‘n-of-m’ processing strategy and interaural electrode insertion depth difference on speech recognition in noise and SRM under conditions that simulated bilateral cochlear implant listening.MethodsFive young adults with normal hearing sensitivity participated in the study. The target sentences were spatially filtered to originate from 0° and the masker was spatially filtered at 0°, 15°, 37.5°, and 90° using the Oldenburg head-related transfer function database for behind the ear microphone. A 22-channel sine wave vocoder processing based on ‘n-of-m’ processing was applied to the spatialized target-masker mixture, in each ear. The perceptual experiment involved a test of speech recognition in noise under one co-located condition (target and masker at 0°) and three spatially separated conditions (target at 0°, masker at 15°, 37.5°, or 90° to the right ear).ResultsThe results were analyzed using a three-way repeated measure analysis of variance (ANOVA). The effect of interaural insertion depth difference (F (2,8) = 3.145, p = 0.098, ɳ2 = 0.007) and spatial separation between target and masker (F (3,12) = 1.239, p = 0.339, ɳ2 = 0.004) on speech recognition in noise was not significant.ConclusionsSpeech recognition in noise and SRM were not affected by IEDD ≤ 3 mm. Bilateral ‘n-of-m’ processing resulted in reduced speech recognition in noise and SRM.

Anatomical and clinical aspects and outcomes of bilateral cochlear implantation in cochlear hypoplasia type IV - a case report

Cochlear hypoplasia is a congenital inner ear malformation (IEM) characterized by a reduced external cochlear dimension, usually accompanied by an abnormal internal architecture. Type IV cochlear hypoplasia is a cochlea with hypoplastic middle and apical turns. It may occur along with dislocation of the facial nerve, associated with semicircular abnormalities, less clearly marked promontory, or stapedial fixation. Such patients can present a broad spectrum of audiological test results, from sensorineural or mixed mild or profound hearing loss. The above anatomical changes may be responsible for intraoperative difficulties during cochlear implantation. In the studied case, a 6-month-old patient was diagnosed with an inner ear malformation - cochlear hypoplasia type IV on both sides. Computed tomography with multiplanar and 3D reconstruction was performed to analyze the middle and inner ear anatomy in detail. Both types of imaging reconstruction helped decide which cochlear implant electrode to choose. Perimodiolar-positioned cochlear implant electrode was found to be the most suitable choice. The patient underwent sequential bilateral cochlear implantation with expected incomplete electrode array insertion on both sides. First repeatable auditory responses were observed two months after the second implant activation. Good parental cooperation with therapists and adequately defined developmental goals in the presented patient allowed the multidisciplinary team to take advantage of the child's intellectual abilities and choose the suitable communication method; however, the patient's auditory responses were obtained slowly. The final auditory results cannot be predicted in inner ear malformations due to abnormal anatomical structure and, thus, heterogeneous innervation within the deformed cochlea. The programming of the sound processor must be individual in each case, based on the child's behavior observation and, if possible, objective test results. Patients with cochlear malformations usually require higher stimulation intensities to obtain sound sensations than patients with a typical cochlear structure.

Interaural asymmetry of dynamic range: Abnormal fusion, bilateral interference, and shifts in attention.

Speech information in the better ear interferes with the poorer ear in patients with bilateral cochlear implants (BiCIs) who have large asymmetries in speech intelligibility between ears. The goal of the present study was to assess how each ear impacts, and whether one dominates, speech perception using simulated CI processing in older and younger normal-hearing (ONH and YNH) listeners. Dynamic range (DR) was manipulated symmetrically or asymmetrically across spectral bands in a vocoder. We hypothesized that if abnormal integration of speech information occurs with asymmetrical speech understanding, listeners would demonstrate an atypical preference in accuracy when reporting speech presented to the better ear and fusion of speech between the ears (i.e., an increased number of one-word responses when two words were presented). Results from three speech conditions showed that: (1) When the same word was presented to both ears, speech identification accuracy decreased if one or both ears decreased in DR, but listeners usually reported hearing one word. (2) When two words with different vowels were presented to both ears, speech identification accuracy and percentage of two-word responses decreased consistently as DR decreased in one or both ears. (3) When two rhyming words (e.g., bed and led) previously shown to phonologically fuse between ears (e.g., bled) were presented, listeners instead demonstrated interference as DR decreased. The word responded in (2) and (3) came from the right (symmetric) or better (asymmetric) ear, especially in (3) and for ONH listeners in (2). These results suggest that the ear with poorer dynamic range is downweighted by the auditory system, resulting in abnormal fusion and interference, especially for older listeners.

The Effects of Multi-Mode Monophasic Stimulation with Capacitive Discharge on the Facial Nerve Stimulation Reduction in Young Children with Cochlear Implants: Intraoperative Recordings.

Facial nerve stimulation (FNS) is a potential complication which may affect the auditory performance of children with cochlear implants (CIs). We carried out an exploratory prospective observational study to investigate the effects of the electrical stimulation pattern on FNS reduction in young children with CI. Ten ears of seven prelingually deafened children with ages up to 6 years old who undergone a unilateral or bilateral CI surgery were included in this study. Electromyographic (EMG) action potentials from orbicularis oculi muscle were recorded using monopolar biphasic stimulation (ST1) and multi-mode monophasic stimulation with capacitive discharge (ST2). Presence of EMG responses, facial nerve stimulation thresholds (T-FNS) and EMG amplitudes were compared between ST1 and ST2. Intra-cochlear electrodes placement, cochlear-nerve and electrode-nerve distances were also estimated to investigate their effects on EMG responses. The use of ST2 significantly reduced the presence of intraoperative EMG responses compared to ST1. Higher stimulation levels were required to elicit FNS with ST2, with smaller amplitudes, compared to ST1. No and weak correlation was observed between cochlea-nerve and electrode-nerve distances and EMG responses, respectively. ST2 may reduce FNS in young children with CI. Differently from the electrical stimulation pattern, the cochlea-nerve and electrode-nerve distances seem to have limited effects on FNS in this population.

Temporal hyper-precision of brainstem neurons alters spatial sensitivity of binaural auditory processing with cochlear implants.

The ability to localize a sound source in complex environments is essential for communication and navigation. Spatial hearing relies predominantly on the comparison of differences in the arrival time of sound between the two ears, the interaural time differences (ITDs). Hearing impairments are highly detrimental to sound localization. While cochlear implants (CIs) have been successful in restoring many crucial hearing capabilities, sound localization via ITD detection with bilateral CIs remains poor. The underlying reasons are not well understood. Neuronally, ITD sensitivity is generated by coincidence detection between excitatory and inhibitory inputs from the two ears performed by specialized brainstem neurons. Due to the lack of electrophysiological brainstem recordings during CI stimulation, it is unclear to what extent the apparent deficits are caused by the binaural comparator neurons or arise already on the input level. Here, we use a bottom-up approach to compare response features between electric and acoustic stimulation in an animal model of CI hearing. Conducting extracellular single neuron recordings in gerbils, we find severe hyper-precision and moderate hyper-entrainment of both the excitatory and inhibitory brainstem inputs to the binaural comparator neurons during electrical pulse-train stimulation. This finding establishes conclusively that the binaural processing stage must cope with highly altered input statistics during CI stimulation. To estimate the consequences of these effects on ITD sensitivity, we used a computational model of the auditory brainstem. After tuning the model parameters to match its response properties to our physiological data during either stimulation type, the model predicted that ITD sensitivity to electrical pulses is maintained even for the hyper-precise inputs. However, the model exhibits severely altered spatial sensitivity during electrical stimulation compared to acoustic: while resolution of ITDs near midline was increased, more lateralized adjacent source locations became inseparable. These results directly resemble recent findings in rodent and human CI listeners. Notably, decreasing the phase-locking precision of inputs during electrical stimulation recovered a wider range of separable ITDs. Together, our findings suggest that a central problem underlying the diminished ITD sensitivity in CI users might be the temporal hyper-precision of inputs to the binaural comparator stage induced by electrical stimulation.

Hearing Preservation and Spatial Hearing Outcomes After Cochlear Implantation in Children With TMPRSS3 Mutations.

Investigate hearing preservation and spatial hearing outcomes in children with TMPRSS3 mutations who received bilateral cochlear implantation. Longitudinal case series report. Two siblings (ages, 7 and 4 yr) with TMPRSS3 mutations with down-sloping audiograms received sequential bilateral cochlear implantation with hearing preservation with low-frequency acoustic amplification and high-frequency electrical stimulation. Spatial hearing, including speech perception and localization, was assessed at three time points: preoperative, postoperative of first and second cochlear implant (CI). Both children showed low-frequency hearing preservation in unaided, acoustic-only audiograms. Both children demonstrated improvements in speech perception in both quiet and noise after CI activations. The emergence of spatial hearing was observed. Each child's overall speech perception and spatial hearing when listening with bilateral CIs were within the range or better than published group data from children with bilateral CIs of other etiology. Bilateral cochlear implantation with hearing preservation is a viable option for managing hearing loss for pediatric patients with TMPRSS3 mutations.

Capturing Visual Attention With Perturbed Auditory Spatial Cues.

Lateralized sounds can orient visual attention, with benefits for audio-visual processing. Here, we asked to what extent perturbed auditory spatial cues-resulting from cochlear implants (CI) or unilateral hearing loss (uHL)-allow this automatic mechanism of information selection from the audio-visual environment. We used a classic paradigm from experimental psychology (capture of visual attention with sounds) to probe the integrity of audio-visual attentional orienting in 60 adults with hearing loss: bilateral CI users (N = 20), unilateral CI users (N = 20), and individuals with uHL (N = 20). For comparison, we also included a group of normal-hearing (NH, N = 20) participants, tested in binaural and monaural listening conditions (i.e., with one ear plugged). All participants also completed a sound localization task to assess spatial hearing skills. Comparable audio-visual orienting was observed in bilateral CI, uHL, and binaural NH participants. By contrast, audio-visual orienting was, on average, absent in unilateral CI users and reduced in NH listening with one ear plugged. Spatial hearing skills were better in bilateral CI, uHL, and binaural NH participants than in unilateral CI users and monaurally plugged NH listeners. In unilateral CI users, spatial hearing skills correlated with audio-visual-orienting abilities. These novel results show that audio-visual-attention orienting can be preserved in bilateral CI users and in uHL patients to a greater extent than unilateral CI users. This highlights the importance of assessing the impact of hearing loss beyond auditory difficulties alone: to capture to what extent it may enable or impede typical interactions with the multisensory environment.

A model framework for simulating spatial hearing of bilateral cochlear implant users

Bilateral cochlear implants (CIs) greatly improve spatial hearing acuity for CI users, but substantial gaps still exist compared to normal-hearing listeners. For example, CI users have poorer localization skills, little or no binaural unmasking, and reduced spatial release from masking. Multiple factors have been identified that limit binaural hearing with CIs. These include degradation of cues due to the various sound processing stages, the viability of the electrode-neuron interface, impaired brainstem neurons, and deterioration in connectivity between different cortical layers. To help quantify the relative importance and inter-relationship between these factors, computer models can and arguably should be employed. While models exploring single stages are often in good agreement with selected experimental data, their combination often does not yield a comprehensive and accurate simulation of perception. Here, we combine information from CI sound processing with computational auditory model stages in a modular and open-source framework, resembling an artificial bilateral CI user. The main stages are (a) binaural signal generation with optional head-related impulse response filtering, (b) generic CI sound processing not restricted to a specific manufacturer, (c) electrode-to-neuron transmission, (d) binaural interaction, and (e) a decision model. The function and the outputs of different model stages are demonstrated with examples of localization experiments. However, the model framework is not tailored to a specific dataset. It offers a selection of sound coding strategies and allows for third-party model extensions or substitutions; thus, it is possible to employ the model for a wide range of binaural applications and even for educational purposes.

Bilateral Cochlear Implant Processing of Coding Strategies With CCi-MOBILE, an Open-Source Research Platform.

While speech understanding for cochlear implant (CI) users in quiet is relatively effective, listeners experience difficulty in identification of speaker and sound location. To assist for better residual hearing abilities and speech intelligibility support, bilateral and bimodal forms of assisted hearing is becoming popular among CI users. Effective bilateral processing calls for testing precise algorithm synchronization and fitting between both left and right ear channels in order to capture interaural time and level difference cues (ITD and ILDs). This work demonstrates bilateral implant algorithm processing using a custom-made CI research platform - CCi-MOBILE, which is capable of capturing precise source localization information and supports researchers in testing bilateral CI processing in real-time naturalistic environments. Simulation-based, objective, and subjective testing has been performed to validate the accuracy of the platform. The subjective test results produced an RMS error of ±8.66° for source localization, which is comparable to the performance of commercial CI processors.

Predictive Ability of First-Side Cochlear Implant Performance in Adult Sequential Bilateral Cochlear Implantation.

Predictors of second-side cochlear implant performance have not been well studied. We sought to assess whether speech recognition scores from first-side cochlear implant (CI1) could predict second-side cochlear implant (CI2) scores in sequential bilaterally implanted adults. Retrospective review using a prospectively collected database. Academic tertiary care hospital. Fifty-seven adults with postimplantation speech recognition testing performed at least 12 months after CI2. Sequential bilateral CI. CI2 performance at ≥12 months as measured using consonant-nucleus-consonant (CNC) words and AzBio sentences in quiet and +10 dB signal-to-noise ratio (S/N). CI1 performance scores at ≥12 months were independently associated with CI2 performance scores at ≥12 months for CNC words (β = 0.371 [0.136-0.606], p = 0.003), AzBio sentences in quiet (β = 0.614 [0.429-0.80], p < 0.0001), and AzBio +10 dB S/N (β = 0.712 [0.459-0.964], p < 0.0001). CI1 scores on AzBio in quiet at 0 to 6 months were also independently associated with CI2 AzBio in quiet scores at ≥12 months (β = 0.389 [0.004-0.774], p = 0.048). Hearing loss etiology and duration, age at implantation, interval between CI1 and CI2, duration of hearing aid use, and preimplantation speech recognition testing scores were not consistently associated with CI2 scores at ≥12 months. CI1 performance is an independent predictor of second-side performance as measured ≥12 months postimplantation. This may be a clinically useful metric when considering adult sequential bilateral implantation.