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.

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.

The impact of spectral and temporal processing on speech recognition in children with cochlear implants.

While the relationships between spectral resolution, temporal resolution, and speech recognition are well defined in adults with cochlear implants (CIs), they are not well defined for prelingually deafened children with CIs, for whom language development is ongoing. This cross-sectional study aimed to better characterize these relationships in a large cohort of prelingually deafened children with CIs (N = 47; mean age = 8.33 years) by comprehensively measuring spectral resolution thresholds (measured via spectral modulation detection), temporal resolution thresholds (measured via sinusoidal amplitude modulation detection), and speech recognition (measured via monosyllabic word recognition, vowel recognition, and sentence recognition in noise via both fixed signal-to-noise ratio (SNR) and adaptively varied SNR). Results indicated that neither spectral or temporal resolution were significantly correlated with speech recognition in quiet or noise for children with CIs. Both age and CI experience had a moderate effect on spectral resolution, with significant effects for spectral modulation detection at a modulation rate of 0.5 cyc/oct, suggesting spectral resolution may improve with maturation. Thus, it is possible we may see an emerging relationship between spectral resolution and speech perception over time for children with CIs. While further investigation into this relationship is warranted, these findings demonstrate the need for new investigations to uncover ways of improving spectral resolution for children with CIs.

Clinical Applications for Spread of Excitation Functions Obtained Via Electrically Evoked Compound Action Potentials (eCAP).

OBJECTIVES: To assess the clinical utility of spread of excitation (SOE) functions obtained via electrically evoked compound action potentials (eCAP) to 1) identify electrode array tip fold-over, 2) predict electrode placement factors confirmed via postoperative computed tomography (CT) imaging, and 3) predict postoperative speech recognition through the first year post-activation in a large clinical sample. STUDY DESIGN: Retrospective case review. SETTING: Cochlear implant (CI) program at a tertiary medical center. PATIENTS: Two hundred seventy-two ears (238 patients) with Cochlear Ltd. CIs (mean age = 46 yr, range = 9 mo-93 yr, 50% female) implanted between August 2014 and December 2022 were included. MAIN OUTCOME MEASURES: eCAP SOE widths (mm) (probe electrodes 5, 11, and 17), incidence of electrode tip fold-over, CT imaging data (electrode-to-modiolus distance, angular insertion depth, scalar location), and speech recognition outcomes (consonant-nucleus-consonant [CNC], AzBio quiet, and +5 dB SNR) through the first year after CI activation. RESULTS: 1) eCAP SOE demonstrated a sensitivity of 85.7% for identifying tip fold-over instances that were confirmed by CT imaging. In the current dataset, the tip fold-over incidence rate was 3.1% (7 patients), with all instances involving a precurved electrode array. 2) There was a significant positive relationship between eCAP SOE and mean electrode-to-modiolus distance for precurved arrays, and a significant positive relationship between eCAP SOE and angular insertion depth for straight arrays. No relationships between eCAP SOE and scalar location or cochlea diameter were found in this sample. 3) There were no significant relationships between eCAP SOE and speech recognition outcomes for any measure or time point, except for a weak negative correlation between average eCAP SOE widths and CNC word scores at 6 months post-activation for precurved arrays. CONCLUSIONS: In the absence of intraoperative CT or fluoroscopic imaging, eCAP SOE is a reasonable alternative method for identifying electrode array tip fold-over and should be routinely measured intraoperatively, especially for precurved electrode arrays with a sheath.

Cochlear implant users experience the sound-to-music effect.

Introduction: The speech-to-song illusion is a robust effect where repeated speech induces the perception of singing; this effect has been extended to repeated excerpts of environmental sounds (sound-to-music effect). Here we asked whether repetition could elicit musical percepts in cochlear implant (CI) users, who experience challenges with perceiving music due to both physiological and device limitations. Methods: Thirty adult CI users and thirty age-matched controls with normal hearing (NH) completed two repetition experiments for speech and nonspeech sounds (water droplets). We hypothesized that CI users would experience the sound-to-music effect from temporal/rhythmic cues alone, but to a lesser magnitude compared to NH controls, given the limited access to spectral information CI users receive from their implants. Results: We found that CI users did experience the sound-to-music effect but to a lesser degree compared to NH participants. Musicality ratings were not associated with musical training or frequency resolution, and among CI users, clinical variables like duration of hearing loss also did not influence ratings. Discussion: Cochlear implants provide a strong clinical model for disentangling the effects of spectral and temporal information in an acoustic signal; our results suggest that temporal cues are sufficient to perceive the sound-to-music effect when spectral resolution is limited. Additionally, incorporating short repetitions into music specially designed for CI users may provide a promising way for them to experience music.

Cochlear Implantation in Very Young Children With Single-Sided Deafness.

OBJECTIVE: Cochlear implants (CIs) for single-sided deafness (SSD) have only been approved for patients 5 years and older despite data supporting that younger children can also benefit from implantation. This study describes our institution's experience with CI for SSD in children 5 years and younger. STUDY DESIGN: Case series with chart review. SETTING: Tertiary referral center. METHODS: A case series with chart review identified 19 patients up to age 5 years who underwent CI for SSD between 2014 and 2022. Baseline characteristics, perioperative complications, device usage, and speech outcomes were collected. RESULTS: The median age at CI was 2.8 (range, 1.0-5.4) years, with 15 (79%) patients being below age 5 at implantation. Etiologies of hearing loss were idiopathic (n = 8), cytomegalovirus (n = 4), enlarged vestibular aqueduct (n = 3), hypoplastic cochlear nerve (n = 3), and meningitis (n = 1). The median preoperative pure-tone average was 90 (range, 75-120) and 20 (range, 5-35) dB eHL in the poor and better hearing ears, respectively. No patients had postoperative complications. Twelve patients achieved consistent device use (average, 9 h/d). Three of the seven who were not consistent users had hypoplastic cochlear nerves and/or developmental delays. The three patients with available preoperative and postoperative speech testing showed significant benefits, and five patients with available postoperative testing demonstrated speech recognition in the implanted ear when isolated from the better ear. CONCLUSION: CI can safely be performed in younger children with SSD. Patients and families accept early implantation, as evidenced by consistent device use, and derive notable benefits in speech recognition. Candidacy can be broadened to include SSD patients under age five years, particularly individuals without hypoplastic cochlear nerves or developmental delay.

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.

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.

Teaching Robotics Coding to a Student with ASD and Severe Problem Behavior.

Research on teaching STEM, especially in the areas of teaching coding for students with ASD, is lacking. The purpose of the current study was to evaluate the effects of using model-lead-test to teach an elementary-aged student with ASD and severe problem behavior the following dependent variables: (a) calibrating the robot; (b) drawing tracks for the robot to follow; and (c) creating a code (e.g., to make the robot move quickly). Results of the multiple probe across skills design demonstrate a functional relation between the model-lead-test strategy and the acquisition of all of the skills. Further, he generalized the coding skill to novel codes, and maintained the skills over time. Implications, study limitations, and recommendations for future research are discussed.