Charles J. Limb

Objectives: To compare low‐frequency‐degraded musical sound quality perception between users of different hearing‐assistive devices. Methods: Fifty‐two adults including 11 normal‐hearing (NH) listeners, eight bilateral hearing aid users (HAHA), 17 bimodal users (CIHA), and 16 bilateral cochlear implant users (CICI) were recruited for a cross‐sectional observational study. Participants assessed the sound quality of 3‐s‐long musical segments (15 sets) using the CI‐Multiple Stimulus with Hidden Reference and Anchor test. Subjects rated and ranked a hidden Reference (“best”); three high‐pass filtered (HPF) versions with low‐frequency cutoffs at 200, 400, and 800 Hz; and an anchor (most degraded version). ART ANOVA with post hoc comparisons was conducted to identify between‐group differences in average perceived sound quality ratings for each stimulus version. Results: Both cohort and degree of low‐frequency degradation had significant effects and interaction on sound quality perception ( p < 0.001). HAHA users rated sound quality higher than both CIHA and CICI users for the 200 and 400 Hz HPF conditions ( p < 0.001), while CIHA and CICI performed similarly. No difference was seen at 800 Hz HPF, suggesting all three hearing‐impaired groups were similarly affected when low‐frequency degradation was severe. Additionally, HAHA, CIHA, and CICI all had difficulty identifying the Reference and correctly ordering stimuli compared to NH. Conclusion: HAHA users exhibit superior sensitivity to low‐frequency sound degradation (≤ 400 Hz) than CI users. These findings elucidate low‐frequency perception limitations as a contributing factor to diminished CI‐mediated musical sound quality and provide evidence for preoperative counseling of implant candidates regarding their postoperative music‐listening experience. Level of Evidence: 3.

Central processing of sound relies on multiple, complex phenomena throughout the pathway between the ear and the brain. The associated processing steps, as well as relevant anatomy and pathophysiology, are presented in this chapter.

Objective: Visualization of cochlear implant (CI) electrode contact position offers insights into electrode–cochlea biomechanics. Prior in vivo imaging studies have assessed electrode distances to a fixed modiolar axis, but electrodes' orientation within the cochlear canal and their relationship to the scala tympani's dynamic anatomical tilt have not been investigated. This study employed in vivo flat‐panel computed tomography (FPCT) imaging to examine the flexibility and dynamic behavior of lateral wall arrays. Methods: This retrospective cohort study included eight MED‐EL FLEX28 CI users. FPCT images were acquired, and reconstructions were aligned to a standardized cochlear coordinate system. Vectors perpendicular to electrode contacts were used to estimate contact orientation using mid‐modiolar image slices and 3D renderings. Anatomical landmarks were used to calculate scalar tilt. Results: A significant correlation was observed between scalar tilt and contact orientation (r = −0.44, p < 0.0001). The scala tympani exhibited its greatest tilt relative to the X–Y plane in the hook region, then transitioned to a parallel orientation at approximately 180° angular depth before increasing tilt again between 180° and 360°. Electrode arrays demonstrated rotational alignment with the scala between 180° and 360° angular insertion depth. Conclusion: Flexible lateral wall electrode arrays accommodate the natural anatomical tilt of the scala tympani, with contact orientation aligning to cochlear structures for much of the insertion trajectory. This in vivo analysis provides new insights into the biomechanical interactions of electrode arrays within the cochlea and may have implications for structure preservation, spectral resolution, and CI stimulation patterns. Level of Evidence: N/A.

Objective: Music is a highly complex acoustic stimulus in both spectral and temporal contents. Accurate representation and delivery of high‐fidelity information are essential for music perception. However, it is unclear how well bone‐anchored hearing implants (BAHIs) transmit music. The study objective is to establish music perception performance baselines for BAHI users and normal hearing (NH) listeners and compare outcomes between the cohorts.Methods: A case‐controlled, cross‐sectional study was conducted among 18 BAHI users and 11 NH controls. Music perception was assessed via performance on seven major musical element tasks: pitch discrimination, melodic contour identification, rhythmic clocking, basic tempo discrimination, timbre identification, polyphonic pitch detection, and harmonic chord discrimination.Results: BAHI users performed comparably well on all music perception tasks with their device compared with the unilateral condition with their better‐hearing ear. BAHI performance was not statistically significantly different from NH listeners' performance. BAHI users performed just as well, if not better than NH listeners when using their control contralateral ear; there was no significant difference between the two groups except for the rhythmic timing (BAHI non‐implanted ear 69% [95% CI: 62%–75%], NH 56% [95% CI: 49%–63%], p = 0.02), and basic tempo tasks (BAHI non‐implanted ear 80% [95% CI: 65%–95%]; NH 75% [95% CI: 68%–82%, p = 0.03]).Conclusions: This study represents the first comprehensive study of basic music perception performance in BAHI users. Our results demonstrate that BAHI users perform as well with their implanted ear as with their contralateral better‐hearing ear and NH controls in the major elements of music perception.Level of Evidence: 3 Laryngoscope, 134:1381–1387, 2024

Cochlear implant (CI) users commonly report degraded musical sound quality. To improve CI-mediated music perception and enjoyment, we must understand factors that affect sound quality. In the present study, we utilize frequency response manipulation (FRM), a process that adjusts the energies of frequency bands within an audio signal, to determine its impact on CI-user sound quality assessments of musical stimuli. Thirty-three adult CI users completed an online study and listened to FRM-altered clips derived from the top songs in Billboard magazine. Participants assessed sound quality using the MUltiple Stimulus with Hidden Reference and Anchor for CI users (CI-MUSHRA) rating scale. FRM affected sound quality ratings (SQR). Specifically, increasing the gain for low and mid-range frequencies led to higher quality ratings than reducing them. In contrast, manipulating the gain for high frequencies (those above 2 kHz) had no impact. Participants with musical training were more sensitive to FRM than non-musically trained participants and demonstrated preference for gain increases over reductions. These findings suggest that, even among CI users, past musical training provides listeners with subtleties in musical appraisal, even though their hearing is now mediated electrically and bears little resemblance to their musical experience prior to implantation. Increased gain below 2 kHz may lead to higher sound quality than for equivalent reductions, perhaps because it offers greater access to lyrics in songs or because it provides more salient beat sensations.

Objective: To evaluate the impact of vocal boost manipulations on cochlear implant (CI) musical sound quality appraisals.Methods: An anonymous, online study was distributed to 33 CI users. Participants listened to auditory tokens and assessed the musical quality of acoustic stimuli with vocal boosting and attenuation using a validated sound quality rating scale. Four versions of real‐world musical stimuli were created: a version with +9 dB vocal boost, a version with −9 dB vocal attenuation, a composite stimulus containing a 1,000 Hz low‐pass filter and white noise (“anchor”), and an unaltered version (“hidden reference”). Subjects listened to all four versions and provided ratings based on a 100‐point scale that reflected the perceived sound quality difference of the music clip relative to the reference excerpt.Results: Vocal boost increased musical sound quality ratings relative to the reference clip (11.7; 95% CI, 1.62–21.8, p = 0.016) and vocal attenuation decreased musical sound quality ratings relative to the reference clip (28.5; 95% CI, 18.64–38.44, p < 0.001). When comparing the non‐musical training group and musical training group, there was a significant difference in musical sound quality rating scores for the vocal boost condition (21.2; 95% CI: 1.76–40.7, p = 0.028).Conclusions: CI‐mediated musical sound quality appraisals are impacted by vocal boost and attenuation. Musically trained CI users to report greater musical sound quality enhancement with a vocal boost with respect to CI users with no musical training background. Implementation of front‐end vocal boost manipulations in music may improve sound quality and music appreciation among CI users.Level of Evidence: 2 (Individual cohort study) Laryngoscope, 133:938–947, 2023

Objectives: To explore the effects of obligatory lexical tone learning on speech emotion recognition and the cross‐culture differences between United States and Taiwan for speech emotion understanding in children with cochlear implant.Methods: This cohort study enrolled 60 cochlear‐implanted (cCI) Mandarin‐speaking, school‐aged children who underwent cochlear implantation before 5 years of age and 53 normal‐hearing children (cNH) in Taiwan. The emotion recognition and the sensitivity of fundamental frequency (F0) changes for those school‐aged cNH and cCI (6–17 years old) were examined in a tertiary referred center.Results: The mean emotion recognition score of the cNH group was significantly better than the cCI. Female speakers' vocal emotions are more easily to be recognized than male speakers' emotion. There was a significant effect of age at test on voice recognition performance. The average score of cCI with full‐spectrum speech was close to the average score of cNH with eight‐channel narrowband vocoder speech. The average performance of voice emotion recognition across speakers for cCI could be predicted by their sensitivity to changes in F0.Conclusions: Better pitch discrimination ability comes with better voice emotion recognition for Mandarin‐speaking cCI. Besides the F0 cues, cCI are likely to adapt their voice emotion recognition by relying more on secondary cues such as intensity and duration. Although cross‐culture differences exist for the acoustic features of voice emotion, Mandarin‐speaking cCI and their English‐speaking cCI peer expressed a positive effect for age at test on emotion recognition, suggesting the learning effect and brain plasticity. Therefore, further device/processor development to improve presentation of pitch information and more rehabilitative efforts are needed to improve the transmission and perception of voice emotion in Mandarin.Level of evidence: 3.

This case report presents the successful use of multiple treatments of electroconvulsive therapy (ECT) in a patient with a cochlear implant (CI). A 60‐year‐old man with a left‐sided CI and bipolar disorder presented with severe depression. A total of 9 separate sessions of unilateral ECT was administered to the contralateral side of the existing CI. We collected subjective, clinical, and audiological assessment of the patient and the CI prior, during, and after ECT therapy. The patient tolerated ECT well and there were no complications. Unilateral ECT was performed contralateral to the CI without any harm to the patient or implant. Laryngoscope, 131:E1695–E1698, 2021

Cochlear implants (CIs) are biomedical devices that restore sound perception for people with severe-to-profound sensorineural hearing loss. Most postlingually deafened CI users are able to achieve ...

Cochlear implants (CIs) are biomedical devices that provide sound to people with severe‐to‐profound hearing loss by direct electrical stimulation of auditory neurons in the cochlea. Despite the remarkable achievements with respect to speech perception in quiet environments, music perception with CIs remains generally poor due to the degradation of auditory input. Prior studies have shown that both pitch perception and timbre discrimination are poor in CI users, whereas the performance on rhythmic tasks is nearly equivalent to normal hearing participants. There are several caveats, however, to this generalization regarding rhythm processing for CI users. The purpose of this article is to summarize the literature on rhythmic perception for CI users while highlighting important limitations within these studies. We will also identify areas for future research and development of CI‐mediated music processing. It is likely that rhythm processing will continue to advance as our understanding of electrical current delivery to the auditory nerve improves.