Long-term effects of non-linear frequency compression for children with moderate hearing loss.

OBJECTIVE: To evaluate non-linear frequency compression (NLFC) as a means to improve speech recognition for children with moderate to moderately-severe hearing loss following a six-month acclimatization period. DESIGN: Within subject design with repeated measures across test conditions. STUDY SAMPLE: Fifteen children, ages 5 to 13 years, with moderate to moderately-severe high-frequency sensorineural hearing loss were fitted with Phonak Nios, micro-sized, BTE hearing aids and evaluated after two six-week intervals with and without NLFC and again after a six-month period of consecutive NLFC use. RESULTS: Using repeated measures analyses, the six-month results were compared to data that was collected following six-week trials with and without NLFC hearing aids (Wolfe et al, in press). Improvements seen with NLFC in the initial study (Wolfe et al, in press) were maintained or significantly increased in the present study. When compared to the six-week data, aided non-sense syllable speech recognition thresholds in quiet and speech recognition in noise were significantly better at the six-month interval. CONCLUSIONS: These results suggest that NLFC improves audibility for and recognition of high-frequency speech sounds for children with moderate to moderately-severe hearing loss. In many cases, improvements found with NLFC increased with a longer period of acclimatization to the technology.

The effect of front-end processing on cochlear implant performance of children.

OBJECTIVE: Previous research shows that children using cochlear implants experience significant difficulty with speech perception in noisy listening situations. There are several types of input signal processing available for the cochlear implant sound processor; however, there is a paucity of research to support this technology for children. The primary objective of this study was to examine the potential benefits of 2 types of input signal processing, adaptive dynamic range optimization (ADRO) as compared with autosensitivity (ASC) plus ADRO for children using Cochlear Corporation implants. RESEARCH DESIGN: Cross-sectional repeated-measures design. SETTING: Outpatient nonprofit foundation providing audiology services and auditory-verbal therapy. PATIENTS: Eleven children, aged 4 years 4 months to 12 years, with unilateral or bilateral Cochlear Limited implants. All children used their cochlear implant(s) for at least 1 year, had no additional disabilities, were enrolled in preschool or elementary school, and had age-appropriate receptive and expressive language. INTERVENTION: All children used Cochlear Limited cochlear implants with either the Nucleus Freedom or Nucleus 5 cochlear implant sound processor. Performance was assessed while these children used ADRO-only input processing and ASC+ADRO input processing. MAIN OUTCOME MEASURES: Speech perception of PBK-50 monosyllabic words in quiet and BKB-SIN sentences in noise was measured for each child. In the noise conditions, children were using the ADRO-only or ASC+ADRO input signal processing strategies. The data in quiet were analyzed with descriptive statistics, and the conditions in noise were compared using a 1-way repeated-measures analysis of variance. RESULTS: All children demonstrated word recognition in quiet at or above 90% correct. In noise, sentence-perception performance in the ASC+ADRO condition was significantly better than that in the ADRO-alone condition. CONCLUSION: The results of the study suggest substantial benefit from combining 2 types of input signal processing, ASC and ADRO, for children with unilateral and bilateral cochlear implants. Specifically, signal processing to adjust the sensitivity of the sound processor microphone automatically has substantial positive effects on speech-perception thresholds in noise.