Consonant and vowel confusions in well-performing adult cochlear implant users, measured with a nonsense syllable repetition test.

OBJECTIVE: The study's objective was to identify consonant and vowel confusions in cochlear implant (CI) users, using a nonsense syllable repetition test. DESIGN: In this cross-sectional study, participants repeated recorded mono- and bisyllabic nonsense words and real-word monosyllables in an open-set design. STUDY SAMPLE: Twenty-eight Norwegian-speaking, well-performing adult CI users (13 unilateral and 15 bilateral), using implants from Cochlear, Med-El and Advanced Bionics, and a reference group of 20 listeners with normal hearing participated. RESULTS: For the CI users, consonants were confused more often than vowels (58% versus 71% correct). Voiced consonants were confused more often than unvoiced (54% versus 64% correct). Voiced stops were often repeated as unvoiced, whereas unvoiced stops were never repeated as voiced. The nasals were repeated correctly in one third of the cases and confused with other nasals in one third of the cases. The real-word monosyllable score was significantly higher than the nonsense syllable score (76% versus 63% correct). CONCLUSIONS: The study revealed a general devoicing bias for the stops and a high confusion rate of nasals with other nasals, which suggests that the low-frequency coding in CIs is insufficient. Furthermore, the nonsense syllable test exposed more perception errors than the real word test.

Sound localising ability in children with bilateral sequential cochlear implants.

OBJECTIVES: To evaluate the sound localisation ability in children with sequential bilateral cochlear implants and the potential influence of age at the time of the first implantation, years of experience with the first implanted ear and the inter-implant interval (time between the first and the second cochlear implantation). METHODS: Sixty-three prelingually deaf children (mean age, 11.03; range, 6.5-17 years; SD, 3.09) were tested after 12 and 24 months of using bilateral cochlear implants. Every child was tested with each ear alone and both ears together. Five loudspeakers were placed in a 180° horizontal arch with 45° of separation between each loudspeaker. The child was placed 1.5m from the speakers. For each test run, three stimuli were presented at 65dB (A) from each speaker for a total of 15 stimulus presentations. For each test run, we calculated the mean angular error (MAE) and the proportion of correct speakers identified (CSS: correct speaker score). Performance by chance for the MAE was 72° and for the CSS was 20% (1 of 5 speakers). RESULTS: After 12 months of using bilateral CIs, the added effect of the second CI in the MAE was minor, and there was no significant difference in CSS between listening in the unilateral condition and listening in bilateral condition. After 24 months, however, the added effect of the second CI in the MAE was significant (mean diff=12.2°; 95% CI; 4.5-20.0°, p=0.003). The mean bilateral CSS increased significantly to 38% (diff=7.7%; 95% CI; 1.4-14.0%; p=0.019) while the mean unilateral CSS remained at a similar level (27%). The influence of age at the time of the first implantation on CSS after 24 months was not significant (p=0.96). However, the inter-implant interval showed a significant decrease in score by 1.4% per year between the two implants (p=0.04). CONCLUSION: Sound localisation with two versus one CI in children with a sequential bilateral cochlear implantation was significantly improved 24 months (but not 12 months) after the second implantation. A shorter inter-implant interval showed a small but significant beneficial effect on sound localisation.

Comparison of bilateral and unilateral cochlear implants in children with sequential surgery.

OBJECTIVE: The objective of this study was to evaluate the effect of bilateral versus unilateral cochlear implants and the importance of the inter-implant interval. METHODS: Seventy-three prelingually deaf children received sequential bilateral cochlear implants. Speech recognition in quiet with the first, second and with both implants simultaneously was evaluated at the time of the second implantation and after 12 and 24 months. RESULTS: Mean bilateral speech recognition 12 and 24 months after the second implantation was significantly higher than that obtained with either the first or the second implant. The addition of a second implant was demonstrated to have a beneficial effect after both 12 and 24 months. Speech recognition with the second implant increased significantly during the first year. A small, non-significant improvement was observed during the second year. The inter-implant interval significantly influenced speech recognition with the second cochlear implant both at 12 and 24 months, and bilateral speech recognition at 12 months, but not at 24 months. CONCLUSIONS: A small, but statistically significant improvement in speech recognition was found with bilateral cochlear implants compared with a unilateral implant. A major increase in speech recognition occurred with the second cochlear implant during the first year. A shorter time interval between the two implantations resulted in better speech recognition with the second implant. However, no definitive time-point was found for when the second implant could no longer add a positive effect.

Unilateral deafness in adults: effects on communication and social interaction.

OBJECTIVES: The aim of this study was to explore the self-reported consequences of profound unilateral deafness regarding communication and social interaction and to compare subjects' speech perception scores to those of normal-hearing individuals who were rendered temporarily unilaterally deaf. METHODS: Cross-sectional data from 30 individuals with unilateral deafness and 30 individuals with normal hearing (age, 14 to 75 years) were obtained through structured interviews and tests of audiovisual, auditory-only, and visual-only speech perception. RESULTS: In individuals with permanent unilateral deafness, 93% reported that hearing loss affected communication. Eighty-seven percent reported problems with speech perception in noisy settings. Other consequences were feelings of exclusion, reduced well-being, and extensive use of speech perception strategies. Inducing temporary unilateral deafness (through short-term blocking of one ear) in normal-hearing subjects produced similar effects on speech perception (27% score) as those experienced by unilaterally deaf subjects (25% score). CONCLUSIONS: Individuals with unilateral deafness experienced a significant disability in auditory function that affected their communication and social interaction. The major challenges were communicating in situations with background noise, in poor acoustic surroundings, and with limited access to speech-reading or direct listening. Under certain listening conditions, long-standing unilateral deafness seemed to yield no advantage over temporary deafness on one side.

Language development in children after receiving bilateral cochlear implants between 5 and 18 months.

OBJECTIVE: The objective of this study was to examine receptive and expressive language development in children who received simultaneous bilateral cochlear implants (CIs) between 5 and 18 months of age and to compare the results with language development in chronologically age-matched children with normal hearing. METHODS: The study used a prospective, longitudinal matched-group design. Data were collected in a clinical setting at postoperative cochlear implant check-ups after 3, 6, 9, 12, 18, 24, 36, and 48 months of implant use. The sample included 42 children: 21 cochlear implant users and 21 with normal hearing, matched pairwise according to gender and chronological age. Communication assessments included the LittlEARS questionnaire, the Mullen Scale of Early Learning, and the Minnesota Child Development Inventory. RESULTS: The cochlear implant users' hearing function according to LittlEARS was comparable to that of normal-hearing children within 9 months post-implantation. The mean scores after 9 and 12 months were 31 and 33, respectively in the prelingually deaf versus 31 and 34 in the normal-hearing children. The children's receptive and expressive language scores showed that after 12-48 months with cochlear implants, 81% had receptive language skills within the normative range and 57% had expressive language skills within the normative range. The number of children who scored within the normal range increased with increasing CI experience. CONCLUSIONS: The present study showed that prelingually deaf children's ability to develop complex expressive and receptive spoken language after early bilateral implantation appears promising. The majority of the children developed language skills at a faster pace than their hearing ages would suggest and over time achieved expressive and receptive language skills within the normative range.