Sound Localization in Patients With Congenital Unilateral Conductive Hearing Loss With a Transcutaneous Bone Conduction Implant.

OBJECTIVE: There is no consensus regarding the benefit of implantable hearing aids in congenital unilateral conductive hearing loss (UCHL). This study aimed to measure sound source localization performance in patients with congenital UCHL and contralateral normal hearing who received a new bone conduction implant. STUDY DESIGN: Evaluation of within-subject performance differences for sound source localization in a horizontal plane. SETTING: Tertiary referral center. PATIENTS: Five patients with atresia of the external auditory canal and contralateral normal hearing implanted with transcutaneous bone conduction implant at the Medical University of Vienna were tested. INTERVENTION: Activated/deactivated implant. MAIN OUTCOME MEASURE: Sound source localization test; localization performance quantified using the root mean square (RMS) error. RESULTS: Sound source localization ability was highly variable among individual subjects, with RMS errors ranging from 21 to 40 degrees. Horizontal plane localization performance in aided conditions showed statistically significant improvement compared with the unaided conditions, with RMS errors ranging from 17 to 27 degrees. The mean RMS error decreased by a factor of 0.71 (p < 0.001). CONCLUSION: Analysis revealed improved sound localization performance in a horizontal plane with the activated transcutaneous bone conduction implant. Some patients with congenital UCHL might be capable of developing improved horizontal plane localization abilities with the binaural cues provided by this device.

Effects of Stimulation Rate With the FS4 and HDCIS Coding Strategies in Cochlear Implant Recipients.

OBJECTIVE: The aim of the present study was to evaluate the effect of stimulation rate on speech perception and sound quality for the fine structure strategy FS4 and the envelope-based strategy high definition continuous interleaved sampling (HDCIS). STUDY DESIGN: Randomized crossover trial with four conditions. SETTING: Tertiary referral. PATIENTS: Twenty-six postlingually deafened adult cochlear implant (CI) recipients were included. INTERVENTION: All subjects were equipped with four coding strategies: FS4 with high rate on the envelope channels (on average 1376 pps/ch), FS4 low rate (750 pps/ch), and HDCIS with the same high and low rates. A "flat-charge map" was used for all four strategies. Only the loudness was balanced between programs. All tests were performed acutely in a double blind manner and a randomized sequence. MAIN OUTCOME MEASURES: Monosyllables in quiet and subjective sound quality. RESULTS: Mean monosyllables scores at 65 dB in quiet were 25.5% correct with HDCIS low rate, 27.2% correct with HDCIS high rate, 25.2% with FS4 low rate, and 33.1% with FS4 high rate. Performance with high stimulation rates was significantly higher than with the low rate settings. Subjective sound quality measured with visual analogue scales showed that for naturalness of speech, the improvement with a high rate version was only evident with the FS4 strategy. In both FS4 and HDCIS, higher stimulation rates elicited a higher pitch and were perceived as less dull than lower rates. CONCLUSION: A high rate of stimulation resulted in better speech recognition in both strategies and a favorable subjective sound quality for FS4 in all tested settings.

Noun plural production in preschoolers with early cochlear implantation: an experimental study of Dutch and German.

OBJECTIVES: Studies investigating language skills of children after cochlear implantation usually present general measures of expressive/receptive vocabulary and grammar and rarely tackle the acquisition of specific language phenomena (word classes, grammatical constructions, word forms, etc.). Furthermore, research is largely restricted to children acquiring English. Cross-linguistic comparisons among children acquiring different languages are almost inexistent. The present study targets the acquisition of noun plurals (e.g., dogs, balls) by Dutch- and German-speaking children implanted before their second birthday. Given its structural complexity and irregularity, noun plural formation is a good indicator of grammatical proficiency in children at risk for a developmental delay. METHODS: The study sample consisted of 14 cochlear-implanted (CI) children (M=55 months of age), 80 age-matched normally hearing (NH) controls, and 40 normally hearing controls matched by Hearing Age (HA). The children were administered an elicitation task in which they had to provide plural forms to a set of singular nouns. The analysis focussed on the following variables: Hearing status (CI, NH), Language (Dutch, German), and Suffix Predictability/Stem Transparency of the plural words. RESULTS: There was no significant difference between children with CI and their NH peers in correct plural production. In both child groups, plural responses followed the predicted pattern of Suffix Predictability/Stem Transparency. However, children with CI significantly more frequently replied to the test item with a recast of the singular noun instead of the plural, and the probability of these responses increased with later age of CI implantation. Furthermore, Dutch-speaking children showed an overall better performance than German-speaking children. CONCLUSIONS: The findings suggest that after 3 years of implant use, preschoolers with early cochlear implantation show age-appropriate patterns of noun plural formation, but still have to catch up with respect to associating a particular singular with its plural form.

Indication criteria and outcomes with the Bonebridge transcutaneous bone-conduction implant.

OBJECTIVES/HYPOTHESIS: The aim of this study was to evaluate functional hearing gain, speech understanding, and preoperative bone-conduction thresholds with the bone-conduction implant Bonebridge. STUDY DESIGN: Retrospective study at a tertiary referral center. METHODS: Twenty-four consecutive Bonebridge patients were identified. Nine patients suffered from combined hearing loss (HL), 12 from atresia of the external auditory canal and three from single-sided deafness. One patient was lost to follow-up. Twenty-three patients were therefore analyzed. RESULTS: The overall average functional hearing gain of all patients (n = 23) was 28.8 dB (±16.1 standard deviation [SD]). Monosyllabic word scores at 65 dB sound pressure level in quiet increased statistically significantly from 4.6 (±7.4 SD) percentage points to 53.7 (±23.0 SD) percentage points. Evaluation of preoperative bone-conduction thresholds revealed three patients with thresholds higher than 45 dB HL in the high frequencies starting at 2 kHz. These three patients had a very limited benefit of their bone-conduction implants. CONCLUSIONS: The Bonebridge bone-conduction implant provides satisfactory results concerning functional gain and speech perception if preoperative bone conduction lies within 45 dB HL. LEVEL OF EVIDENCE: 4.

FS4, FS4-p, and FSP: a 4-month crossover study of 3 fine structure sound-coding strategies.

OBJECTIVES: The aim of the present study was to compare two novel fine structure strategies "FS4" and "FS4-p" with the established fine structure processing (FSP) strategy. FS4 provides fine structure information on the apical four-electrode channels. With FS4-p, these electrodes may be stimulated in a parallel manner. The authors evaluated speech perception, sound quality, and subjective preference. DESIGN: A longitudinal crossover study was done on postlingually deafened adults (N = 33) who were using FSP as their default strategy. Each participant was fitted with FS4, FS4-p, and FSP, for 4 months in a randomized and blinded order. After each run, an Adaptive Sentence test in noise (Oldenburger Sentence Test [OLSA]) and a Monosyllable test in quiet (Freiburger Monosyllables) were performed, and subjective sound quality was determined with a Visual Analogue Scale. At the end of the study the preferred strategy was noted. RESULTS: Scores of the OLSA did not reveal any significant differences among the three strategies, but the Freiburger test showed a statistically significant effect (p = 0.03) with slightly worse scores for FS4 (49.7%) compared with FSP (54.3%). Performance of FS4-p (51.8%) was comparable with the other strategies. Both audiometric tests depicted a high variability among subjects. The number of best-performing strategies for each participant individually was as follows: (a) for the OLSA: FSP, N = 10.5; FS4, N = 10.5; and FS4-p, N = 12; and (b) for the Freiburger test: FSP, N = 14; FS4, N = 9; and FS4-p, N = 10. A moderate agreement was found in the best-performing strategies of the Speech tests within the participants. For sound quality, speech in quiet, classical, and pop music were assessed. No significant effects of strategy were found for speech in quiet and classical music, but auditory impression of pop music was rated as more natural in FSP compared with FS4 (p = 0.04). It is interesting that at the end of the study, a majority of the participants favored the new coding strategies over their previous default FSP (FSP, N = 13; FS4, N = 13; FS4-p, N = 7). CONCLUSIONS: In summary, FS4 and FS4-p offer new and further options in audio processor fitting, with similar levels of speech understanding in noise as FSP. This is an interesting result, given that the strategies' presentation of temporal fine structure differs from FSP. At the end of the study, 20 of 33 subjects chose either FS4 or FS4-p over their previous default strategy FSP.

Envelope versus fine structure speech coding strategy: a crossover study.

OBJECTIVE: The transmission of fine structure information to cochlear implant users is an expanding area of research. Previous studies comparing the fine structure processing (FSP) speech coding strategy to the envelope-based continuous interleaved sampling (CIS) strategy indicated improved speech perception when using the fine structure strategy. Those investigations were performed with an extended frequency spectrum in the low frequencies together with the fine structure strategy. The current study addresses the question whether these improvements are due to the presentation of fine structure per se or rather the extended frequency spectrum. Hence, this cross over study compares the two strategies using an identical frequency spectrum. STUDY DESIGN: Randomized crossover study. PATIENTS: 31 patients were randomly assigned to two groups. INTERVENTIONS: One group was fitted with a CIS map for 4 weeks, tested and subsequently fitted with a FSP map for 4 weeks. The other group followed the same pattern in reverse. MAIN OUTCOME MEASURES: Test material consisted of sentence tests in noise, monosyllables in quiet and melody recognition. RESULTS: No statistical significance was noted between the different speech coding strategies at an identical frequency spectrum. CONCLUSION: This study shows that there is no difference in speech perception with FSP compared to CIS at an extended frequency spectrum. Therefore, the extended frequency spectrum in the low frequencies might explain a benefit of FSP observed in previous studies.

Residual hearing preservation using the suprameatal approach for cochlear implantation.

OBJECTIVE: Cochlear implantation of patients with high-frequency hearing loss and residual low-frequency hearing has become a new treatment standard within the last years. The objective of this study was to evaluate the rate of hearing preservation in cochlear implantation for electric-acoustic stimulation using the suprameatal approach. METHODS: Five patients (mean age 48.2 years) who were supplied with Med El (Combi 40+, Pulsar) cochlear implants and various different electrodes (Custom made, Flex soft, Flex EAS) were evaluated for residual hearing preservation after a mean follow-up time of 35.6 months (range 24 to 77 months). RESULTS: Three patients showed partial hearing preservation, whereas 2 patients experienced a complete loss of residual hearing. CONCLUSION: Although hearing preservation rates in this series of patients operated on using the suprameatal approach were inferior as compared with a series using the standard mastoidectomy approach, this study shows that it is in fact possible to preserve residual hearing using a non-mastoidectomy surgical technique for cochlear implantation. Nevertheless, more experience is necessary to answer the question whether this technique can be thoroughly recommended in cochlear implantation for electric-acoustic stimulation.