Temporal coding and music perception in bimodal listeners.

OBJECTIVE: Limited low frequency (LF) pitch and temporal fine structure (TFS) sensitivity have been thought to contribute significantly to poor music perception in cochlear implant (CI) listeners. Thus, this study aimed to evaluate music perception in relation to LF pitch perception and temporal coding, specifically in people with bimodal stimulation as a promising approach to improve spectro-temporal sensitivity in CI listeners. METHODS: Eleven postlingually deafened bimodal listeners participated in the study (mean age=55.5 years, range 36-75 years, SD=11.7). LF pitch/TFS sensitivity was evaluated by using two recently developed tests: Harmonic Intonation (HI) and Disharmonic Intonation (DI). The music perception protocol was based on three audio files in the genres of Classical, Jazz and Soul music and a music quality questionnaire regarding four subjective aspects: Clarity, Pleasantness, Naturalness and General Quality of Sounds. RESULTS: CI alone and bimodal findings showed statistically significant differences for both temporal coding and music perception. DI findings showed statistically significant correlations with music quality ratings (p<0.05). CONCLUSION: Bimodal music quality ratings were significantly better, indicating a significant improvement in the quality of music towards being significantly more clear, more natural, more pleasant, and better quality. Similarly, bimodal HI/DI findings improved significantly, although the amount of benefit was greater for the DI task with spectral information only below 300 Hz. Significant DI correlations with music quality ratings supported the test to be more indicative of better temporal coding of LF residual hearing and its effects on music perception.

The role of speech rate for Italian-speaking cochlear implant users: insights for everyday speech perception.

This study investigated the effect of speech rate for Italian-speaking cochlear implant (CI) users with the aim of gaining insight into everyday listening situations where speaker's rate may vary considerably together with speech level in fluctuating background noise. The test material was prepared by processing the Italian STARR test with temporal compression of sentence material. Twelve adult CI users were divided into two subgroups based on their STARR performance: good and poor performers. The effect of varying speech rate was remarkable for both subgroups. Good performers showed significant performance deterioration for the faster speech rate, whereas outcomes for poor performers improved significantly for the slower speech rate. Background noise is inevitable during daily life and CI users face a variety of speakers, so must cope with changes in both speech level and rate. Traditional tests with a single talker speaking very clearly while using a moderate to low speech rate may overestimate everyday speech perception for CI users. The use of tests that mimic everyday perception is of great importance and should become a routine part of audiometric measures for hearing impaired people.

Temporal Fine Structure Processing, Pitch, and Speech Perception in Adult Cochlear Implant Recipients.

OBJECTIVES: The aim of the study was to investigate the link between temporal fine structure (TFS) processing, pitch, and speech perception performance in adult cochlear implant (CI) recipients, including bimodal listeners who may benefit better low-frequency (LF) temporal coding in the contralateral ear. DESIGN: The study participants were 43 adult CI recipients (23 unilateral, 6 bilateral, and 14 bimodal listeners). Two new LF pitch perception tests-harmonic intonation (HI) and disharmonic intonation (DI)-were used to evaluate TFS sensitivity. HI and DI were designed to estimate a difference limen for discrimination of tone changes based on harmonic or inharmonic pitch glides. Speech perception was assessed using the newly developed Italian Sentence Test with Adaptive Randomized Roving level (STARR) test where sentences relevant to everyday contexts were presented at low, medium, and high levels in a fluctuating background noise to estimate a speech reception threshold (SRT). RESULTS: Although TFS and STARR performances in the majority of CI recipients were much poorer than those of hearing people reported in the literature, a considerable intersubject variability was observed. For CI listeners, median just noticeable differences were 27.0 and 147.0 Hz for HI and DI, respectively. HI outcomes were significantly better than those for DI. Median STARR score was 14.8 dB. Better performers with speech reception thresholds less than 20 dB had a median score of 8.6 dB. A significant effect of age was observed for both HI/DI tests, suggesting that TFS sensitivity tended to worsen with increasing age. CI pure-tone thresholds and duration of profound deafness were significantly correlated with STARR performance. Bimodal users showed significantly better TFS and STARR performance for bimodal listening than for their CI-only condition. Median bimodal gains were 33.0 Hz for the HI test and 95.0 Hz for the DI test. DI outcomes in bimodal users revealed a significant correlation with unaided hearing thresholds for octave frequencies lower than 1000 Hz. Median STARR scores were 17.3 versus 8.1 dB for CI only and bimodal listening, respectively. STARR performance was significantly correlated with HI findings for CI listeners and with those of DI for bimodal listeners. CONCLUSIONS: LF pitch perception was found to be abnormal in the majority of adult CI recipients, confirming poor TFS processing of CIs. Similarly, the STARR findings reflected a common performance deterioration with the HI/DI tests, suggesting the cause probably being a lack of access to TFS information. Contralateral hearing aid users obtained a remarkable bimodal benefit for all tests. Such results highlighted the importance of TFS cues for challenging speech perception and the relevance to everyday listening conditions. HI/DI and STARR tests show promise for gaining insights into how TFS and speech perception are being limited and may guide the customization of CI program parameters and support the fine tuning of bimodal listening.

Adaptation of the STARR test for adult Italian population: A speech test for a realistic estimate in real-life listening conditions.

OBJECTIVES: To introduce the Italian adaptation of the STARR test based on a roving-level adaptive method to mimic challenging real-life listening conditions for use in people with auditory prostheses. DESIGN: Normative data were collected and interlist-variability, as well as learning effects, were investigated using a within-subject design with repeated measures. STUDY SAMPLE: A group of 32 normal-hearing (NH) adults participated in the study. RESULTS: The average speech reception threshold (SRT) for NH subjects was -8.4 dB SNR. The variability of mean SRTs across test lists was relatively small (≤1 dB for all test lists). The statistically significant differences between lists were eliminated after applying correction factors. On the basis of variability for the corrected SRTs within each subject, a difference of 2.8 dB in SRT was meaningful for outcome comparisons using one test list per condition and 2 dB using two lists per condition. Statistical analysis did not show any significant learning effects. CONCLUSIONS: Findings in NH listeners suggested that the Italian STARR test could be a promising supplement to existing speech assessment tools. Further studies in populations with hearing impairment could contribute to cross-language studies.

Low-frequency pitch perception in children with cochlear implants in comparison to normal hearing peers.

The aim of the present study was to investigate the application of two new pitch perception tests in children with cochlear implants (CI) and to compare CI outcomes to normal hearing (NH) children, as well as investigating the effect of chronological age on performance. The tests were believed to be linked to the availability of Temporal Fine Structure (TFS) cues. 20 profoundly deaf children with CI (5-17 years) and 31 NH peers participated in the study. Harmonic Intonation (HI) and Disharmonic Intonation (DI) tests were used to measure low-frequency pitch perception. HI/DI outcomes were found poorer in children with CI. CI and NH groups showed a statistically significant difference (p < 0.001). HI scores were better than those of DI test (p < 0.001). Chronological age had a significant effect on DI performance in NH group (p < 0.05); children under the age of 8.5 years showed larger inter-subject-variability; however, the majority of NH children showed outcomes that were considered normal at adult-level. For the DI test, bimodal listeners had better performance than when listening with CI alone. HI/DI tests were applicable as clinical tools in the pediatric population. The majority of CI users showed abnormal outcomes on both tests confirming poor TFS processing in the hearing-impaired population. Findings indicated that the DI test provided more differential low-frequency pitch perception outcomes in that it reflected phase locking and TFS processing capacities of the ear, whereas HI test provided information of its place coding capacity as well.

Long term results in late implanted adolescent and adult CI recipients.

The aim of the present study is to assess long-term outcomes of CI in prelingual deafened adolescents and adults, describing, where present, differences in performance, self perceived benefit and highlighting specific characteristics. Twenty-three patients were enrolled: 10 adolescents, 13 young adults. Each patient underwent speech perception/language development, psychological evaluation and structured interviews on self perception concerning CI. 70 % adolescents and 100 % adults used their cochlear implant for most of the day; two adolescents were partial users and one was a non-user. Adolescents' average word recognition and comprehension scores improved respectively from 7 to 29.8 % (p = 0.01) and 3 to 26 % (p = 0.1). Adults' average scores improved significantly from 1.5 to 41.9 % (p = 0.01) and from 18.5 to 52.7% (p = 0.001), respectively. None of the subjects showed a linguistic age adequate to the chronological one: average linguistic age was 7.6 years for adolescents and 19.3 for adults. Structured interviews showed improvement in self-esteem. Adults and most adolescents were fully or moderately satisfied with their implant. Cochlear implantation can be considered a valid option for the rehabilitation of highly motivated and well-selected pre-lingual deafened adolescents and adults. Although there is a substantial variability in both groups of patients and language skills are only marginally influenced by CI, there is still a significant improvement in speech perception. CI was described by both groups as having had a positive impact on their lives; nevertheless adolescents were the ones with a tendency to under-use CI, even those with better hearing outcomes.

Implementation of perceptual channels in children implanted with a HiRes 90K device.

CONCLUSIONS: The increased spectral resolution that characterizes the HiRes 120 device contributes to improvement of performance. Discrimination and identification in noise are consistent with reports of improved perception under everyday listening situations. OBJECTIVES: This work focuses on speech perception findings after implementation of current steering in HiResolution strategy of children implanted with Clarion HiRes 90K. SUBJECTS AND METHODS: Comparison was made between three groups of children: standard HiRes control group, a second group switched over from HiRes to HiRes 120 and the third group switched on with HiRes 120. Children were tested before and 12 months after implementation of HiRes 120. A standard test battery was administered to obtain a speech perception development profile. The Auditory Speech Sound Evaluation (A section signE) test was carried out to evaluate discrimination and identification of phonemes in quiet and in noise. RESULTS: The HiRes and HiRes 120 switch-over groups showed quite similar results for speech perception in quiet. However, the HiRes 120 switch-over group achieved these results within a shorter time after conversion. Switch-on children showed improvement in all speech perception categories, reaching approximately 60% recognition and 30% comprehension in quiet. Results for A section signE discrimination scores in quiet and noise showed a clear improvement for both HiRes 120 switch-on and switch-over groups compared with the HiRes group.

Schooling and educational performance in children and adolescents wearing cochlear implants.

OBJECTIVE: The aim of the study was to assess the impact of cochlear implant use on schooling. DESIGN: Retrospective study which examined the educational characteristics, gap between chronological age and class attended, learning skills and quality of social interaction with peers and adults in 50 children with cochlear implants. METHODS: Structured interviews with parents, questionnaires for teachers, school report cards and psychometric tests. RESULTS: Majority of children attended state schools in mainstreamed classes; 88% had a support teacher and 86% followed Oral Communication. These children showed a smaller disparity (0.4 years) between their chronological age and class attended. No insufficient performers were seen in learning skills. Greater competence in linguistic and logical areas tended to correspond to more intensive rehabilitation. Children were cooperative, assertive with peers and grew fond of teachers and communication assistants. CONCLUSIONS: Schooling proved to be satisfactory in prelingually deafened children and adolescents wearing cochlear implants.