Frequency-Limiting Effects on Speech and Environmental Sound Identification for Cochlear Implant and Normal Hearing Listeners

BACKGROUND AND OBJECTIVES: It is important to understand the frequency region of cues used, and not used, by cochlear implant (CI) recipients. Speech and environmental sound recognition by individuals with CI and normal-hearing (NH) was measured. Gradients were also computed to evaluate the pattern of change in identification performance with respect to the low-pass filtering or high-pass filtering cutoff frequencies. SUBJECTS AND METHODS: Frequency-limiting effects were implemented in the acoustic waveforms by passing the signals through low-pass filters (LPFs) or high-pass filters (HPFs) with seven different cutoff frequencies. Identification of Korean vowels and consonants produced by a male and female speaker and environmental sounds was measured. Crossover frequencies were determined for each identification test, where the LPF and HPF conditions show the identical identification scores. RESULTS: CI and NH subjects showed changes in identification performance in a similar manner as a function of cutoff frequency for the LPF and HPF conditions, suggesting that the degraded spectral information in the acoustic signals may similarly constraint the identification performance for both subject groups. However, CI subjects were generally less efficient than NH subjects in using the limited spectral information for speech and environmental sound identification due to the inefficient coding of acoustic cues through the CI sound processors. CONCLUSIONS: This finding will provide vital information in Korean for understanding how different the frequency information is in receiving speech and environmental sounds by CI processor from normal hearing.

Otolaryngological Manifestation of Hunter Syndrome / 대한이비인후과학회지

BACKGROUND AND OBJECTIVE: Hunter syndrome(mucopolysaccharidosis (MPS) type II) is a genetic, metabolic disease of excessive mucopolysaccharide storage leading to mental and skeletal abnormalities, distinctive facial features, hearing loss, and airway problems. Its eventual lethal outcome results from cardiac failure and progressive obstruction of the airway. We tried to outline the otolaryngologic manifestations and management of patients based on the results of our study and review of the relevant literature. MATERIALS AND METHODS: Nine patients with Hunter syndrome were included in this study. Every patient was interviewed for the evaluation of any abnormality in the head and neck region, intelligence and language. Audio tests, temporal bone CT, and plain films of cervical spine were also performed. RESULTS: Upper airway obstruction occurred in most of patients, and necessitated tonsillectomy and adenoidectomy in 4 patients. Tracheal narrowing occurred in 3 patients. Otitis media with effusion, hearing loss and thickening of the external auditory canal and tympanic membrane were commonly observed in patients, and ventilation tubes were inserted in 4 patients. Mental retardation was more profound in the severe type Hunter syndrome, but speech function was disordered in both severe and mild type. CONCLUSION: Accurate evaluation and management of airway obstruction is needed to prevent lethal airway problems. Aggressive audio and otological managements, including the management of otitis media, hearing aids and speech therapy are required to enhance communicative development and improve their quality of life.