The effect of cochlear implantation on music perception by adults with usable pre-operative acoustic hearing

Tonotopic and Default Frequency Fitting for Music Perception in Cochlear Implant Recipients: A Randomized Clinical Trial

Importance

Cochlear implants are an effective technique for enhancing speech perception abilities in quiet environments for people with severe to profound deafness. Nevertheless, complex sound signals perception, such as music perception, remains challenging for cochlear implant users.

Objective

To assess the benefit of a tonotopic map on music perception in new cochlear implant users.

Design, Setting, and Participants

A prospective, randomized, double-blind, 2-period crossover study including 26 new cochlear implant users was performed over a 6-month period (June 2021 to November 2021). An anatomical tonotopic map was created using postoperative flat-panel computed tomography and a reconstruction software based on Greenwood function. New cochlear implant users older than 18 years with bilateral severe to profound sensorineural hearing loss or complete hearing loss for less than 5 years were selected in the University Hospital Centre of Rennes in France. The trial was conducted from June to November 2021 (inclusion) and to February 2022 (end of the assessment procedure at 12 weeks postactivation), and the analysis itself was completed in December 2022.

Intervention

Each participant was randomized to receive a conventional map followed by a tonotopic map or vice versa.

Main Outcomes and Measures

Participants performed pitch-scaling tasks (multidimensional qualitative assessment, melodic contour identification, melodic recognition test) after 6 weeks of each setting.

Results

Thirteen participants were randomized to each sequence. Two of the 26 participants recruited (1 in each sequence) had to be excluded due to the COVID-19 pandemic. The multidimensional qualitative assessment (Gabrielsson test), melodic contour identification, and melodic recognition scores were significantly higher with the tonotopic setting than the conventional one (mean effect [ME], 7.8; 95% CI, 5.0-10.5; ME, 12.1%; 95% CI, 5.7%-18.4%; ME, 14.4%, 95% CI, 8.5%-20.2%; and ME, 2.1, 95% CI, 1.7-2.5, respectively). Among the different dimensions evaluated by the Gabrielsson test, the mean scores for clarity, spaciousness, fullness, nearness, and total impression were significantly higher with tonotopic fitting. Ninety-two percent of the participants kept the tonotopy-based map after the study period.

Conclusions

In this randomized clinical trial of patients with new cochlear implants, a tonotopic-based fitting was associated with better results in perception of complex sound signals such as music listening experience.

Trial Registration

ClinicalTrials.gov Identifier: NCT04922619.

Importance of ipsilateral residual hearing for spatial hearing by bimodal cochlear implant users

Bimodal cochlear implant (CI) listeners have difficulty utilizing spatial cues to segregate competing speech, possibly due to tonotopic mismatch between the acoustic input frequency and electrode place of stimulation. The present study investigated the effects of tonotopic mismatch in the context of residual acoustic hearing in the non-CI ear or residual hearing in both ears. Speech recognition thresholds (SRTs) were measured with two co-located or spatially separated speech maskers in normal-hearing adults listening to acoustic simulations of CIs; low frequency acoustic information was available in the non-CI ear (bimodal listening) or in both ears. Bimodal SRTs were significantly better with tonotopically matched than mismatched electric hearing for both co-located and spatially separated speech maskers. When there was no tonotopic mismatch, residual acoustic hearing in both ears provided a significant benefit when maskers were spatially separated, but not when co-located. The simulation data suggest that hearing preservation in the implanted ear for bimodal CI listeners may significantly benefit utilization of spatial cues to segregate competing speech, especially when the residual acoustic hearing is comparable across two ears. Also, the benefits of bilateral residual acoustic hearing may be best ascertained for spatially separated maskers.

Advantages of Pulse Rate Compared to Modulation Frequency for Temporal Pitch Perception in Cochlear Implant Users

Most cochlear implants encode the fundamental frequency of periodic sounds by amplitude modulation of constant-rate pulsatile stimulation. Pitch perception provided by such stimulation strategies is markedly poor. Two experiments are reported here that consider potential advantages of pulse rate compared to modulation frequency for providing stimulation timing cues for pitch. The first experiment examines beat frequency distortion that occurs when modulating constant-rate pulsatile stimulation. This distortion has been reported on previously, but the results presented here indicate that distortion occurs for higher stimulation rates than previously reported. The second experiment examines pitch resolution as provided by pulse rate compared to modulation frequency. The results indicate that pitch discrimination is better with pulse rate than with modulation frequency. The advantage was large for rates near what has been suggested as the upper limit of temporal pitch perception conveyed by cochlear implants. The results are relevant to sound processing design for cochlear implants particularly for algorithms that encode fundamental frequency into deep envelope modulations or into precisely timed pulsatile stimulation.

Assessment of music experience after cochlear implantation: A review of current tools and their utilization

Objective

To provide an overview of the current available music assessment tools after cochlear implantation (CI); to report on the utilization of music assessments in the literature; to propose potential future directions in music assessment after CI.

Methods

A thorough search was performed in PubMed, Embase, and The Cochrane Library through October 31, 2020. MeSH search terms, keywords, and phrases included “cochlear implant,” “cochlear prosthesis,” “auditory prosthesis,” “music,” “music assessment,” “music questionnaire,” “music perception,” “music enjoyment, and “music experience.” Potentially relevant studies were reviewed for inclusion, with particular focus on assessments developed specifically for the cochlear implant population and intended for widespread use.

Results/conclusions

Six hundred and forty-three studies were screened for relevance to assessment of music experience among cochlear implantees. Eighty-one studies ultimately met criteria for inclusion. There are multiple validated tools for assessment of music experience after cochlear implantation, each of which provide slightly differing insights into the patients’ subjective and/or objective post-activation experience. However, no single assessment tool has been adopted into widespread use and thus, much of the literature pertaining to this topic evaluates outcomes non-uniformly, including single-use assessments designed specifically for the study at hand. The lack of a widely accepted universal tool for assessment of music limits our collective understanding the contributory and mitigating factors applicable to current music experience of cochlear implantees, and limits our ability to uniformly evaluate the success of new implant technologies or music training paradigms.

An evaluation framework for research platforms to advance cochlear implant/hearing aid technology: A case study with CCi-MOBILE

Cochlear implants (CIs) and hearing aids (HAs) are advanced assistive hearing devices that perform sound processing to achieve acoustic to acoustic/electrical stimulation, thus enabling the prospects for hearing restoration and rehabilitation. Since commercial CIs/HAs are typically constrained by manufacturer design/production constraints, it is necessary for researchers to use research platforms (RPs) to advance algorithms and conduct investigational studies with CI/HA subjects. While previous CI/HA research platforms exist, no study has explored establishing a formal evaluation protocol for the operational safety and reliability of RPs. This study proposes a two-phase analysis and evaluation paradigm for RPs. In the acoustic phase 1 step, a signal processing acoustic space is explored in order to present a sampled set of audio input content to explore the safety of the resulting output electric/acoustic stimulation. In the parameter phase 2 step, the configurable space for realizable electrical stimulation pulses is determined, and overall stimulation reliability and safety are evaluated. The proposed protocol is applied and demonstrated using Costakis Cochlear Implant Mobile. Assessment protocol observations, results, and additional best practices for subsampling of the acoustic and parameter test spaces are discussed. The proposed analysis-evaluation protocol establishes a viable framework for assessing RP operational safety and reliability. Guidelines for adapting the proposed protocol to address variability in RP configuration due to experimental factors such as custom algorithms, stimulation techniques, and/or individualization are also considered.

Effects of noise on integration of acoustic and electric hearing within and across ears

In bimodal listening, cochlear implant (CI) users combine electric hearing (EH) in one ear and acoustic hearing (AH) in the other ear. In electric-acoustic stimulation (EAS), CI users combine EH and AH in the same ear. In quiet, integration of EH and AH has been shown to be better with EAS, but with greater sensitivity to tonotopic mismatch in EH. The goal of the present study was to evaluate how external noise might affect integration of AH and EH within or across ears. Recognition of monosyllabic words was measured for normal-hearing subjects listening to simulations of unimodal (AH or EH alone), EAS, and bimodal listening in quiet and in speech-shaped steady noise (10 dB, 0 dB signal-to-noise ratio). The input/output frequency range for AH was 0.1–0.6 kHz. EH was simulated using an 8-channel noise vocoder. The output frequency range was 1.2–8.0 kHz to simulate a shallow insertion depth. The input frequency range was either matched (1.2–8.0 kHz) or mismatched (0.6–8.0 kHz) to the output frequency range; the mismatched input range maximized the amount of speech information, while the matched input resulted in some speech information loss. In quiet, tonotopic mismatch differently affected EAS and bimodal performance. In noise, EAS and bimodal performance was similarly affected by tonotopic mismatch. The data suggest that tonotopic mismatch may differently affect integration of EH and AH in quiet and in noise.

Development and validation of the audio processor satisfaction questionnaire (APSQ) for hearing implant users

Objective: The satisfaction experienced with using an audio processor is very important to hearing implant system users. Currently there are no measures that can be used to assess user satisfaction with an audio processor. This study aims to develop and validate a specific and standardised questionnaire that focuses on user satisfaction with their audio processor.Design: A preliminary version of the questionnaire was initially developed by experts in the field. Following validation of these results, the final version of the Audio Processor Satisfaction Questionnaire (APSQ) was developed consisting of 15 items. Item analyses and questionnaire validation measurements were assessed.Study sample: Sixty-nine subjects were recruited and asked to complete the APSQ twice within 2-4 weeks.Results: Subjects reported a high user satisfaction with the questionnaire and with their audio processor. The questionnaire had good reliability and results for test-retest reliability were high and significant across all items and across subscale analyses.Conclusion: Item analyses and reliability analyses show that the questionnaire is a valid and reliable tool to assess user satisfaction across different audio processors and hearing implant systems. The APSQ is a quick and easy tool to measure user satisfaction with their audio processor.

Tripolar Stimulation Improves Polyphonic Pitch Detection in Cochlear Implant Users

OBJECTIVE

Cochlear implant (CI) users struggle with pitch perception, particularly for polyphonic stimuli. Tripolar (TP) stimulation has been proposed as a way to mitigate the broad spread of neural excitation observed in traditional monopolar (MP) stimulation, thereby potentially improving perception of polyphony.

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary academic center.

PATIENTS

Eleven postlingually deafened adults with Advanced Bionics HiRes 90K CIs.

INTERVENTION(S)

We performed pitch ranking and polyphonic pitch detection testing under MP and TP configurations. To assess pitch ranking, users were asked to identify the higher pitch between two notes. In polyphonic pitch detection, users were asked to distinguish between single-pitch tones and two-pitch tones. Two-pitch stimuli consisted of one pitch of three base frequencies (392, 523, 740 Hz) and a second pitch between 1 and 12 semitones above the base frequency.

MAIN OUTCOME MEASURE

Pitch performance was analyzed as a function of current delivery mode (tripolar vs. monopolar), with smaller semitone interval pitch resolution indicating better performance.

RESULTS

In pitch ranking tasks, TP configuration did not confer an advantage over MP stimulation. In polyphonic perception, however, tripolar stimulation improved performance in lower frequencies and resulted in statistically significant (p < 0.05) improvement at the highest base frequency, 740 Hz.

CONCLUSIONS

These data suggest that TP configuration may confer an advantage in the perception of polyphonic pitch, which may not be observed in monophonic pitch ranking tasks. Since music is typically polyphonic, such data offer approaches toward improving perception of real-world musical stimuli.

Music Appreciation of Adult Hearing Aid Users and the Impact of Different Levels of Hearing Loss

OBJECTIVES

The main aim of this study was to collect information on music listening and music appreciation from postlingually deafened adults who use hearing aids (HAs). It also sought to investigate whether there were any differences in music ratings from HA users with different levels of hearing loss (HL; mild, versus moderate to moderately-severe, versus severe or worse.

DESIGN

An existing published questionnaire developed for cochlear implant recipients was modified for this study. It had 51 questions divided into seven sections: (1) music listening and music background; (2) sound quality; (3) musical styles; (4) music preferences; (5) music recognition; (6) factors affecting music listening enjoyment; and (7) music training program. The questionnaire was posted out to adult HA users, who were subsequently divided into three groups: (i) HA users with a mild HL (Mild group); (ii) HA users with a moderate to moderately-severe HL (Moderate group); and (iii) HA users with a severe or worse (Severe group) HL.

RESULTS

One hundred eleven questionnaires were completed; of these, 51 participants had a mild HL, 42 had a moderate to moderately-severe loss, and 18 a severe or worse loss. Overall, there were some significant differences noted, predominantly between the Mild and Severe groups, with fewer differences between the Mild and Moderate groups. The respondents with the greater levels of HL reported a greater reduction in their music enjoyment as a result of their HL and that HAs made music sound significantly less melodic for them. It was also observed that the Severe group's mean scores for both the pleasant rating as well as the combined rating for the six different musical styles were lower than both the Mild and Moderate groups' ratings for every style, with just one exception (pop/rock pleasantness rating). There were significant differences between the three groups for the styles of music that were reported to sound the best with HA(s), as well as differences between the ratings on more specific timbre rating scales used to rate different elements of each style. In rating the pleasantness and naturalness of different musical instruments or instrumental groups, there was no difference between the groups. There were also significant differences between the Mild and Severe groups in relation to musical preferences for the pitch range of music, with the Severe group significantly preferring male singers and lower pitched instruments.

CONCLUSIONS

The overall results indicated little difference in music appreciation between those with a mild versus moderate loss. However, poorer appreciation scores were given by those with a severe or worse HL. This would suggest that HAs or HL have a negative impact on music listening, particularly when the HL becomes more significant. There was a large degree of variability in ratings, though, with music listening being satisfactory for some listeners and largely unsatisfactory for others, in all three groups. Music listening preferences also varied significantly, and the reported benefit (or otherwise) provided by the HA for music was also mixed. The overriding variability in listening preferences and ratings leads to the question as to the benefit and effectiveness of generic, manufacturer-derived music programs on HAs. Despite the heterogeneity in the listening habits, preferences, and ratings, it is clear that music appreciation and enjoyment is still challenging for many HA users and that level of HL is one, but not the only factor that impacts on music appreciation.

Assessing and treating adult patients with hearing loss

Hearing loss is a very common presentation both in primary and secondary care. In addition to causing significant morbidity, it can make communication with patients very challenging, and thus impact other aspects of their care. This article presents an approach to the assessment and management of this condition.

The Benefits of Residual Hair Cell Function for Speech and Music Perception in Pediatric Bimodal Cochlear Implant Listeners

Objective

The aim of this study was to investigate the benefits of residual hair cell function for speech and music perception in bimodal pediatric Mandarin-speaking cochlear implant (CI) listeners.

Design

Speech and music performance was measured in 35 Mandarin-speaking pediatric CI users for unilateral (CI-only) and bimodal listening. Mandarin speech perception was measured for vowels, consonants, lexical tones, and sentences in quiet. Music perception was measured for melodic contour identification (MCI).

Results

Combined electric and acoustic hearing significantly improved MCI and Mandarin tone recognition performance, relative to CI-only performance. For MCI, performance was significantly better with bimodal listening for all semitone spacing conditions (p < 0.05 in all cases). For tone recognition, bimodal performance was significantly better only for tone 2 (rising; p < 0.05). There were no significant differences between CI-only and CI + HA for vowel, consonant, or sentence recognition.

Conclusions

The results suggest that combined electric and acoustic hearing can significantly improve perception of music and Mandarin tones in pediatric Mandarin-speaking CI patients. Music and lexical tone perception depends strongly on pitch perception, and the contralateral acoustic hearing coming from residual hair cell function provided pitch cues that are generally not well preserved in electric hearing.

Integration of acoustic and electric hearing is better in the same ear than across ears

Advances in cochlear implant (CI) technology allow for acoustic and electric hearing to be combined within the same ear (electric-acoustic stimulation, or EAS) and/or across ears (bimodal listening). Integration efficiency (IE; the ratio between observed and predicted performance for acoustic-electric hearing) can be used to estimate how well acoustic and electric hearing are combined. The goal of this study was to evaluate factors that affect IE in EAS and bimodal listening. Vowel recognition was measured in normal-hearing subjects listening to simulations of unimodal, EAS, and bimodal listening. The input/output frequency range for acoustic hearing was 0.1–0.6 kHz. For CI simulations, the output frequency range was 1.2–8.0 kHz to simulate a shallow insertion depth and the input frequency range was varied to provide increasing amounts of speech information and tonotopic mismatch. Performance was best when acoustic and electric hearing was combined in the same ear. IE was significantly better for EAS than for bimodal listening; IE was sensitive to tonotopic mismatch for EAS, but not for bimodal listening. These simulation results suggest acoustic and electric hearing may be more effectively and efficiently combined within rather than across ears, and that tonotopic mismatch should be minimized to maximize the benefit of acoustic-electric hearing, especially for EAS.

Reduction of the Harmonic Series Influences Musical Enjoyment With Cochlear Implants

OBJECTIVE

Cochlear implantation is associated with poor music perception and enjoyment. Reducing music complexity has been shown to enhance music enjoyment in cochlear implant (CI) recipients. In this study, we assess the impact of harmonic series reduction on music enjoyment.

STUDY DESIGN

Prospective analysis of music enjoyment in normal-hearing (NH) individuals and CI recipients.

SETTING

Single tertiary academic medical center.

PATIENTS

NH adults (N = 20) and CI users (N = 8) rated the Happy Birthday song on three validated enjoyment modalities-musicality, pleasantness, and naturalness.

INTERVENTION

Subjective rating of music excerpts.

MAIN OUTCOME MEASURES

Participants listened to seven different instruments play the melody, each with five levels of harmonic reduction (Full, F3+F2+F1+F0, F2+F1+F0, F1+F0, F0). NH participants listened to the segments both with and without CI simulation. Linear mixed effect models (LME) and likelihood ratio tests were used to assess the impact of harmonic reduction on enjoyment.

RESULTS

NH listeners without simulation rated segments with the first four harmonics (F3+F2+F1+F0) most pleasant and natural (p <0.001, p = 0.004). NH listeners with simulation rated the first harmonic alone (F0) most pleasant and natural (p <0.001, p = 0.003). Their ratings demonstrated a positive linear relationship between harmonic reduction and both pleasantness (slope estimate = 0.030, SE = 0.004, p <0.001, LME) and naturalness (slope estimate = 0.012, SE = 0.003, p = 0.003, LME). CI recipients also found the first harmonic alone (F0) to be most pleasant (p = 0.003), with a positive linear relationship between harmonic reduction and pleasantness (slope estimate = 0.029, SE = 0.008, p <0.001, LME).

CONCLUSION

Harmonic series reduction increases music enjoyment in CI and NH individuals with or without CI simulation. Therefore, minimization of the harmonics may be a useful strategy for enhancing musical enjoyment among both NH and CI listeners.

Pitch and lexical tone perception of bilingual English-Mandarin-speaking cochlear implant recipients, hearing aid users, and normally hearing listeners

OBJECTIVES

The purpose of this current study was to investigate whether pitch, lexical tone, and/or speech-in-noise perception were significantly correlated for Singaporean teenagers or adults who spoke both Mandarin and English.

METHODS

Thirty-three normal hearing or near-normal hearing listeners who did not use a hearing device (NNH group), eight postlingually deafened cochlear implant (CI) recipients (CI group), and three postlingually deafened bilateral hearing aid (HA) users (HA group) were recruited. All participants were bilingual Mandarin-English-speaking Singaporean residents. Participants were assessed on tests of pitch-ranking, lexical tone perception, and speech-in-noise.

RESULTS

The NNH group scored significantly better than the CI group for all tests and subtests. There were no significant differences for the pitch test between the HA group and either the CI or NNH group. However, HA users scored significantly better than the CI group, and more aligned with the NNH group's scores for both the lexical tone and Mandarin speech-in-noise test. There were highly significant moderate positive correlations between all three tests. Discussion Overall, the performance of the CI users in this study indicates that CI recipients still struggle on pitch-related auditory perception tasks. Additionally, although the test scores from the HA users were better than the CI recipients, they were not as good as the NNH listeners. The significant moderate correlations between all three tests indicate that there is at least some degree of overlap in the skills required to accurately perceive these stimuli.

CONCLUSION

The overall results suggest that CI users, and to a lesser extent HA users, still struggle with complex auditory perceptual tasks, particularly when it requires the perception of pitch. However, it may be possible that training one of these skills (e.g. musical pitch) may then generalize to other tasks (e.g. lexical tone and/or speech-in-noise). This is important for counseling, as well as for planning effective rehabilitation programs.

The Effects of Training on Music Perception and Appreciation for Cochlear Implant Recipients

The aim of this study was to compare the effectiveness of a music appreciation training program (MATP) to that of focused music listening (FML) for improving music and/or speech in noise perception for postlingually deafened cochlear implant (CI) recipients. It was hypothesized that the MATP would show greater improvements than FML. Ten CI recipients were randomly divided into two groups: one undertaking the MATP and the other undertaking FML. Participants completed four 30-minute sessions per week for 8 weeks, with tests of music and speech-in-noise perception being administered four times per participant: before and after a control period, immediately after the intervention, and 4–8 weeks after intervention. There was a significant pre- to posttraining difference for the MATP group on the instrument identification test, as well as for half of the quality rating assessments. Although no statistically significant improvements were obtained for the FML group, there was a trend of higher scores postintervention for the instrument and ensemble identification tests, and compliance was substantially better than for the MATP group. While the results showed that only the music training significantly improved music perception, the potential of FML to benefit some CI recipients for some tasks was also observed.

Music Engineering as a Novel Strategy for Enhancing Music Enjoyment in the Cochlear Implant Recipient

Objective. Enjoyment of music remains an elusive goal following cochlear implantation. We test the hypothesis that reengineering music to reduce its complexity can enhance the listening experience for the cochlear implant (CI) listener. Methods. Normal hearing (NH) adults (N = 16) and CI listeners (N = 9) evaluated a piece of country music on three enjoyment modalities: pleasantness, musicality, and naturalness. Participants listened to the original version along with 20 modified, less complex, versions created by including subsets of the musical instruments from the original song. NH participants listened to the segments both with and without CI simulation processing. Results. Compared to the original song, modified versions containing only 1–3 instruments were less enjoyable to the NH listeners but more enjoyable to the CI listeners and the NH listeners with CI simulation. Excluding vocals and including rhythmic instruments improved enjoyment for NH listeners with CI simulation but made no difference for CI listeners. Conclusions. Reengineering a piece of music to reduce its complexity has the potential to enhance music enjoyment for the cochlear implantee. Thus, in addition to improvements in software and hardware, engineering music specifically for the CI listener may be an alternative means to enhance their listening experience.

Using the HISQUI29 to assess the sound quality levels of Spanish adults with unilateral cochlear implants and no contralateral hearing

To evaluate cochlear implant (CI) users' self-reported level of sound quality and quality of life (QoL). Sound quality was self-evaluated using the hearing implant sound quality index (HISQUI29). HISQUI29 scores were further examined in three subsets. QoL was self-evaluated using the glasgow benefit inventory (GBI). GBI scores were further examined in three subsets. Possible correlations between the HISQUI29 and GBI were explored. Additional possible correlations between these scores and subjects' pure tone averages, speech perception scores, age at implantation, duration of hearing loss, duration of CI use, gender, and implant type were explored. Subjects derived a "moderate" sound quality level from their CI. Television, radio, and telephone tasks were easier in quiet than in background noise. 89 % of subjects reported their QoL benefited from having a CI. Mean total HISQUI29 score significantly correlated with all subcategories of the GBI. Age at implantation inversely correlated with the total HISQUI29 score and with television and radio understanding. Sentence in noise scores significantly correlated with all sound perception scores. Women had a better mean score in music perception and in telephone use than did men. CI users' self-reported levels of sound quality significantly correlated with their QoL. Cochlear implantation had a beneficial impact on subjects' QoL. Understanding speech is easier in quiet than in noise. Music perception remains a challenge for many CI users. The HISQUI29 and the GBI can provide useful information about the everyday effects of future treatment modalities, rehabilitation strategies, and technical developments.

Dichotic Listening Can Improve Perceived Clarity of Music in Cochlear Implant Users

Musical enjoyment for cochlear implant (CI) recipients is often reported to be unsatisfactory. Our goal was to determine whether the musical experience of postlingually deafened adult CI recipients could be enriched by presenting the bass and treble clef parts of short polyphonic piano pieces separately to each ear (dichotic). Dichotic presentation should artificially enhance the lateralization cues of each part and help the listeners to better segregate them and thus provide greater clarity. We also hypothesized that perception of the intended emotion of the pieces and their overall enjoyment would be enhanced in the dichotic mode compared with the monophonic (both parts in the same ear) and the diotic mode (both parts in both ears). Twenty-eight piano pieces specifically composed to induce sad or happy emotions were selected. The tempo of the pieces, which ranged from lento to presto covaried with the intended emotion (from sad to happy). Thirty participants (11 normal-hearing listeners, 11 bimodal CI and hearing-aid users, and 8 bilaterally implanted CI users) participated in this study. Participants were asked to rate the perceived clarity, the intended emotion, and their preference of each piece in different listening modes. Results indicated that dichotic presentation produced small significant improvements in subjective ratings based on perceived clarity. We also found that preference and clarity ratings were significantly higher for pieces with fast tempi compared with slow tempi. However, no significant differences between diotic and dichotic presentation were found for the participants’ preference ratings, or their judgments of intended emotion.

Judgment of musical emotions after cochlear implantation in adults with progressive deafness

While cochlear implantation is rather successful in restoring speech comprehension in quiet environments (Nimmons et al., 2008), other auditory tasks, such as music perception, can remain challenging for implant users. Here, we tested how patients who had received a cochlear implant (CI) after post-lingual progressive deafness perceive emotions in music. Thirteen adult CI recipients with good verbal comprehension (dissyllabic words ≥70%) and 13 normal hearing participants matched for age, gender, and education listened to 40 short musical excerpts that selectively expressed fear, happiness, sadness, and peacefulness ( Vieillard et al., 2008). The participants were asked to rate (on a 0–100 scale) how much the musical stimuli expressed these four cardinal emotions, and to judge their emotional valence (unpleasant–pleasant) and arousal (relaxing–stimulating). Although CI users performed above chance level, their emotional judgments (mean correctness scores) were generally impaired for happy, scary, and sad, but not for peaceful excerpts. CI users also demonstrated deficits in perceiving arousal of musical excerpts, whereas rating of valence remained unaffected. The current findings indicate that judgments of emotional categories and dimensions of musical excerpts are not uniformly impaired after cochlear implantation. These results are discussed in relation to the relatively spared abilities of CI users in perceiving temporal (rhythm and metric) as compared to spectral (pitch and timbre) musical dimensions, which might benefit the processing of musical emotions (Cooper et al., 2008).

A partial hearing animal model for chronic electro-acoustic stimulation

OBJECTIVE

Cochlear implants (CIs) have provided some auditory function to hundreds of thousands of people around the world. Although traditionally carried out only in profoundly deaf patients, the eligibility criteria for implantation have recently been relaxed to include many partially-deaf patients with useful levels of hearing. These patients receive both electrical stimulation from their implant and acoustic stimulation via their residual hearing (electro-acoustic stimulation; EAS) and perform very well. It is unclear how EAS improves speech perception over electrical stimulation alone, and little evidence exists about the nature of the interactions between electric and acoustic stimuli. Furthermore, clinical results suggest that some patients that undergo cochlear implantation lose some, if not all, of their residual hearing, reducing the advantages of EAS over electrical stimulation alone. A reliable animal model with clinically-relevant partial deafness combined with clinical CIs is important to enable these issues to be studied. This paper outlines such a model that has been successfully used in our laboratory.

APPROACH

This paper outlines a battery of techniques used in our laboratory to generate, validate and examine an animal model of partial deafness and chronic CI use.

MAIN RESULTS

Ototoxic deafening produced bilaterally symmetrical hearing thresholds in neonatal and adult animals. Electrical activation of the auditory system was confirmed, and all animals were chronically stimulated via adapted clinical CIs. Acoustic compound action potentials (CAPs) were obtained from partially-hearing cochleae, using the CI amplifier. Immunohistochemical analysis allows the effects of deafness and electrical stimulation on cell survival to be studied.

SIGNIFICANCE

This animal model has applications in EAS research, including investigating the functional interactions between electric and acoustic stimulation, and the development of techniques to maintain residual hearing following cochlear implantation. The ability to record CAPs via the CI has clinical direct relevance for obtaining objective measures of residual hearing.

Neural adaptation and behavioral measures of temporal processing and speech perception in cochlear implant recipients

The objective was to determine if one of the neural temporal features, neural adaptation, can account for the across-subject variability in behavioral measures of temporal processing and speech perception performance in cochlear implant (CI) recipients. Neural adaptation is the phenomenon in which neural responses are the strongest at the beginning of the stimulus and decline following stimulus repetition (e.g., stimulus trains). It is unclear how this temporal property of neural responses relates to psychophysical measures of temporal processing (e.g., gap detection) or speech perception. The adaptation of the electrical compound action potential (ECAP) was obtained using 1000 pulses per second (pps) biphasic pulse trains presented directly to the electrode. The adaptation of the late auditory evoked potential (LAEP) was obtained using a sequence of 1-kHz tone bursts presented acoustically, through the cochlear implant. Behavioral temporal processing was measured using the Random Gap Detection Test at the most comfortable listening level. Consonant nucleus consonant (CNC) word and AzBio sentences were also tested. The results showed that both ECAP and LAEP display adaptive patterns, with a substantial across-subject variability in the amount of adaptation. No correlations between the amount of neural adaptation and gap detection thresholds (GDTs) or speech perception scores were found. The correlations between the degree of neural adaptation and demographic factors showed that CI users having more LAEP adaptation were likely to be those implanted at a younger age than CI users with less LAEP adaptation. The results suggested that neural adaptation, at least this feature alone, cannot account for the across-subject variability in temporal processing ability in the CI users. However, the finding that the LAEP adaptive pattern was less prominent in the CI group compared to the normal hearing group may suggest the important role of normal adaptation pattern at the cortical level in speech perception.

Clinical selection criteria for a second cochlear implant for bimodal listeners

OBJECTIVE

To compare the speech perception benefit, provided by a contralateral hearing aid (HA) or a second cochlear implant (CI).

STUDY DESIGN

Repeated measures.

PATIENTS

A total of 25 adult subjects participated in the study, including 12 bilateral (10 female and 2 male patients) and 13 bimodal (6 female and 7 male subjects) users. All bilateral users were sequentially implanted. The bimodal users were separated into a poor group (n = 5, aided pure-tone average (PTA) of 55 dB HL or greater at audiometric frequencies of 1 kHz or lesser) and a good group (n = 8, aided PTA < 55 dB HL).

MAIN OUTCOME MEASURES

Consonant, vowel, and sentence recognition was measured in quiet and noise at +5 dB and +10 dB signal-to-noise ratios (SNRs). Speech recognition performance was evaluated under three listening conditions: CI alone, HA alone, and CI+HA for bimodal users; first CI alone, second CI alone, and first CI + second CI for bilateral users when speech and noise were presented from the front.

RESULTS

There was no significant difference in the binaural benefit between the good bimodal and bilateral groups in vowel and sentence recognition. However, the binaural benefit is significantly better in the bilateral group than in the poor bimodal group for all 3 speech measures.

CONCLUSION

These results suggest that the aided pure-tone average at audiometric frequencies of 1 kHz or lesser may serve as one of the clinical criteria for the recommendation of whether bimodal patients should consider a second cochlear implant to maximize their binaural listening ability.

MUSIC APPRECIATION AND TRAINING FOR COCHLEAR IMPLANT RECIPIENTS: A REVIEW

In recent years, there has been increasing interest in music perception of cochlear implant (CI) recipients, and a growing body of research conducted in this area. The majority of these studies have examined perceptual accuracy for pitch, rhythm, and timbre. Another important, but less commonly studied aspect of music listening is appreciation, or appraisal. Despite the ongoing research into potential technological improvements that may improve music perception for recipients, both perceptual accuracy and appreciation generally remain poor for most recipients. Whilst perceptual accuracy for music is important, appreciation and enjoyment also warrants research as it also contributes to clinical outcomes and perceived benefits. Music training is being shown to offer excellent potential for improving music perception and appreciation for recipients.Therefore, the primary topics of this review are music appreciation and training. However, a brief overview of the psychoacoustic, technical, and physiological factors associated with a recipient's perception of music is provided, as these are important factors in understanding the listening experience for CI recipients. The purpose of this review is to summarize key papers that have investigated these issues, in order to demonstrate that i) music enjoyment and appraisal is an important and valid consideration in evaluating music outcomes for recipients, and ii) that music training can improve music listening for many recipients, and is something that can be offered to persons using current technology.

Comparison of bimodal and bilateral cochlear implant users on speech recognition with competing talker, music perception, affective prosody discrimination, and talker identification

OBJECTIVES

Despite excellent performance in speech recognition in quiet, most cochlear implant users have great difficulty with speech recognition in noise, music perception, identifying tone of voice, and discriminating different talkers. This may be partly due to the pitch coding in cochlear implant speech processing. Most current speech processing strategies use only the envelope information; the temporal fine structure is discarded. One way to improve electric pitch perception is to use residual acoustic hearing via a hearing aid on the nonimplanted ear (bimodal hearing). This study aimed to test the hypothesis that bimodal users would perform better than bilateral cochlear implant users on tasks requiring good pitch perception.

DESIGN

Four pitch-related tasks were used. 1. Hearing in Noise Test (HINT) sentences spoken by a male talker with a competing female, male, or child talker. 2. Montreal Battery of Evaluation of Amusia. This is a music test with six subtests examining pitch, rhythm and timing perception, and musical memory. 3. Aprosodia Battery. This has five subtests evaluating aspects of affective prosody and recognition of sarcasm. 4. Talker identification using vowels spoken by 10 different talkers (three men, three women, two boys, and two girls). Bilateral cochlear implant users were chosen as the comparison group. Thirteen bimodal and 13 bilateral adult cochlear implant users were recruited; all had good speech perception in quiet.

RESULTS

There were no significant differences between the mean scores of the bimodal and bilateral groups on any of the tests, although the bimodal group did perform better than the bilateral group on almost all tests. Performance on the different pitch-related tasks was not correlated, meaning that if a subject performed one task well they would not necessarily perform well on another. The correlation between the bimodal users' hearing threshold levels in the aided ear and their performance on these tasks was weak.

CONCLUSIONS

Although the bimodal cochlear implant group performed better than the bilateral group on most parts of the four pitch-related tests, the differences were not statistically significant. The lack of correlation between test results shows that the tasks used are not simply providing a measure of pitch ability. Even if the bimodal users have better pitch perception, the real-world tasks used are reflecting more diverse skills than pitch. This research adds to the existing speech perception, language, and localization studies that show no significant difference between bimodal and bilateral cochlear implant users.

A comparison of the speech recognition and pitch ranking abilities of children using a unilateral cochlear implant, bimodal stimulation or bilateral hearing aids

OBJECTIVE

The present study compared the speech recognition and pitch ranking abilities of normally hearing children (n=15) to children using a cochlear implant (CI) alone (n=8), bilateral hearing aids (HAs) (n=6), or bimodal stimulation (BMS) (n=9). It was hypothesised that users of BMS would score higher on tasks of speech and pitch perception than children using a CI alone, but not children using HAs.

METHODS

Participants were assessed on tasks of monosyllabic word recognition in quiet, sentence recognition in quiet and noise (10 dB signal-to-noise ratio), and a pitch ranking task using pairs of sung vowels one, half, and a quarter of an octave apart.

RESULTS

There were no significant differences between the mean percentage-correct scores of the four participant groups for either words in quiet or sentences in quiet and noise. However, the proportion of bimodal users who scored >80% correct (80%) was significantly greater than the proportion of high-scoring unilateral CI (25%) or bilateral HA users (17%). Contrary to expectations, there was also no significant difference between the pitch ranking scores of users of BMS and users of a CI alone for all three interval sizes (p<0.05, RM-ANOVA). However participants using only acoustic hearing (i.e. the NH and HA groups) scored significantly higher than participants using electrical stimulation (i.e. the CI and BMS groups) on the pitch ranking task (p<0.05; RM-ANOVA).

CONCLUSIONS

Contrary to findings in postlingually deafened adults, we found no significant bimodal advantage for pitch perception in prelingually deafened children. However, the performance of children using electrical stimulation was significantly poorer than children using only acoustic stimulation. Further research is required to investigate the contribution of the non-implanted ears of users of BMS to pitch perception, and the effect of hearing loss on the development of pitch perception in children.

Music Therapy for Preschool Cochlear Implant Recipients

This paper provides research and clinical information relevant to music therapy for preschool children who use cochlear implants (CI). It consolidates information from various disciplinary sources regarding (a) cochlear implantation of young prelingually-deaf children (~age 2-5), (b) patterns of auditory and speech-language development, and (c) research regarding music perception of children with CIs. This information serves as a foundation for the final portion of the article, which describes typical music therapy goals and examples of interventions suitable for preschool children.

What breaks a melody: perceiving F0 and intensity sequences with a cochlear implant

Pitch perception has been extensively studied using discrimination tasks on pairs of single sounds. When comparing pitch discrimination performance for normal-hearing (NH) and cochlear implant (CI) listeners, it usually appears that CI users have relatively poor pitch discrimination. Tasks involving pitch sequences, such as melody perception or auditory scene analysis, are also usually difficult for CI users. However, it is unclear whether the issue with pitch sequences is a consequence of sound discriminability, or if an impairment exists for sequence processing per se. Here, we compared sequence processing abilities across stimulus dimensions (fundamental frequency and intensity) and listener groups (NH, CI, and NH listeners presented with noise-vocoded sequences). The sequence elements were firstly matched in discriminability, for each listener and dimension. Participants were then presented with pairs of sequences, constituted by up to four elements varying on a single dimension, and they performed a same/different task. In agreement with a previous study (Cousineau et al., 2009) fundamental frequency sequences were processed more accurately than intensity sequences by NH listeners. However, this was not the case for CI listeners, nor for NH listeners presented with noise-vocoded sequences. Intensity sequence processing was, nonetheless, equally accurate in the three groups. These results show that the reduced pitch cues received by CI listeners do not only elevate thresholds, as previously documented, but also affect pitch sequence processing above threshold. We suggest that efficient sequence processing for pitch requires the resolution of individual harmonics in the auditory periphery, which is not achieved with the current generation of implants.

Music Perception in Children With Cochlear Implants

As a result of the widespread use of cochlear implants, individuals with profound hearing loss now are able to hear sounds ranging from a syllable to a symphony. This form of “electric hearing” has been remarkably successful in providing sound to the deaf population and at least 100,000 implantation procedures have been performed worldwide in more than 80 countries (Clark, 2008). Today, it is routine for post-lingual deafened individuals (one who lost their hearing after normal childhood language acquisition) to achieve high performance on language tests following implantation (Lalwani, Larky, Wareing, Kwast, & Schindler, 1998). Deaf children implanted at an early age with a CI usually develop excellent spoken language skills, with placement into mainstream educational schooling (Francis, Koch, Wyatt, & Niparko, 1999). The overwhelming emphasis on language perception in CI users has led to relative neglect of non-linguistic sound perception. Yet, the auditory world consists of many other sounds besides those of spoken language. Of all non-linguistic sounds, perception of music—particularly pitch and timbre—represents the greatest challenge for implant-mediated listening (Limb, 2006). High-level perception of music rarely is attained through conventional speech processing technology in adults or children. Recent technological advances, however, have increased the processing capabilities of modern CIs and hold great promise for music perception and quality of life for children with cochlear implants (Lassaletta et al., 2007).

Experience-induced malleability in neural encoding of pitch, timbre, and timing

Speech and music are highly complex signals that have many shared acoustic features. Pitch, Timbre, and Timing can be used as overarching perceptual categories for describing these shared properties. The acoustic cues contributing to these percepts also have distinct subcortical representations which can be selectively enhanced or degraded in different populations. Musically trained subjects are found to have enhanced subcortical representations of pitch, timbre, and timing. The effects of musical experience on subcortical auditory processing are pervasive and extend beyond music to the domains of language and emotion. The sensory malleability of the neural encoding of pitch, timbre, and timing can be affected by lifelong experience and short-term training. This conceptual framework and supporting data can be applied to consider sensory learning of speech and music through a hearing aid or cochlear implant.

The family oriented musical training for children with cochlear implants: speech and musical perception results of two year follow-up

OBJECTIVE

The purpose of this study is to determine whether children can gain benefit from training on pitch and music perception. Our main goals were to prepare a tool for training pitch and rhythm perception and evaluate musical attitude in children, to determine whether pitch and rhythm perception improve more rapidly through training and to assess the impact of training on speech perception.

METHOD

A family centred habilitation program based on musical training is developed. Nine newly implanted children who were switched on in HiRes and trained from the outset and 9 children using HiRes strategy who did not receive training both undergo assessments to determine pitch and rhythm perception skills and speech perception assessments. Music group was formed by the children who were implanted consecutively. As a control group, children who are being followed for another study which examines "the changes of sound quality perception, speech understanding, speech production, and communication mode" are included. The speech perception test battery contains a comprehensive range of age appropriate tasks covering detection, discrimination, identification, recognition and comprehension abilities. Also meaningful auditory integration scale (MAIS) or infant-toddler MAIS (if more appropriate) and the meaningful use of speech scale (MUSS) were administered in order to collect information about children's use of sound in everyday situations such as device bounding, alerting to sound and deriving meaning from auditory stimuli. Musical training program was based on a take-home electric keyboard which is used for listening to different pairs of notes. For this study, three octaves and one extra note at the high end of the keyboard were used. Children were expected to discriminate a pair of notes. Assessments of speech perception at pre-implant, 1-, 3-, 6-, 12-, 24-months post switch-on. By the end of the first and second years, parents were given the 'musical stages questionnaire' which covers some of the key areas of musical development to compare both groups' musical development.

RESULTS

Children who were involved in music study demonstrated significant familiarity in both determining pitch differences. No significant difference was found between music group compared with the non-trained group in terms of speech perception (p>0.05). However, by the end of 3rd month, music group came into prominence particularly at the rate of being linguistically/developmentally ready to carry out formal modified open-set speech perception evaluation (p<0.05). Both groups seemed to be developed similarly in sound awareness and general reaction, differentiating melody, dynamic, rhythmical changes and emotional aspects of musical development (p>0.05) whereas music group had more exposure to music at the end of the first year (p<0.05). However, by the end of the second year music group developed more than the control group in all aspects of musical skills (p<0.05).

CONCLUSION

Music training program helps appreciation of music and may enhance their progress in other auditory domains after cochlear implantation in children. While, effects of the musical training program on daily listening attitudes and social aspects such as closer parent-child relationship were significantly observed future training programs that should strive to improve satisfaction with music listening and its effect on auditory perception.