Graeme Clark Collection
Permanent URI for this collection
Search Results
1 - 3 of 3
-
ItemSpeech perception results for children with implants with different levels of preoperative residual hearing( 1997)Objective: Many reports have established that hearing-impaired children using the Nucleus 22 channel cochlear implant may show both significant benefits to lipreading and significant scores on open-set words and sentences using electrical stimulation only. These findings have raised questions about whether severely or severely-to-profoundly deaf children should be candidates for cochlear implants. To study this question, postoperative results for implanted children with different levels of preoperative residual hearing were evaluated in terms of speech perception benefits. Study Design/Setting: A retrospective study of the first 117 children, sequentially, to undergo implantation in the Melbourne and Sydney Cochlear Implant Clinics was undertaken. All children had been assessed by and received their implants in a tertiary referral centre. Main Outcome Measures: To assess aided residual hearing, the children were grouped into four categories of hearing on the basis of their aided residual hearing thresholds measured preoperatively. To assess benefits, the scores of children on standard speech perception tests were reviewed. As different tests were used for children with different ages and language skills, children were grouped into categories according to the level of postoperative speech perception benefit. Results: The results showed that children in the higher categories of aided preoperative residual hearing showed significant scores on open-set word and sentence perception tests using the implant alone. For children in lower categories of aided residual hearing, results were variable within the groups. More than 90% of children with implants with aided residual hearing thresholds in the speech range above I kHz achieved open-set understanding of words and sentences. Conclusion: While the results of this preliminary study confirm previous findings of differential outcomes for children with different levels of preoperative residual hearing, they suggest that children with severe to profound hearing impairments should be considered for cochlear implantation.
-
ItemContinuing improvements in speech processing for adult cochlear implant patients( 1995)The Cochlear 22-channel cochlear implant has employed a succession of improved speech-processing strategies since its first use in an adult patient in Melbourne in 1982. 1 The first patients received the F0F2 coding strategy developed by the University of Melbourne, in the Wearable Speech Processor (WSP). The F0F2 coding scheme presented the implant user with three acoustic features of speech. These were 1) the amplitude of the waveform, presented as the amount of current charge, 2) fundamental frequency (F0) or voice pitch, presented as rate of biphasic pulsatile stimulation, and 3) the spectral range of the second formant frequency (F2), which was represented by varying the site of stimulation along the electrode array.
-
ItemIntracochlear factors contributing to psychophysical percepts following cochlear implantation: a case study( 1995)It is conceivable that the variations of performance of cochlear implant patients can be related to several factors. Shiroma et al 1 investigated which factors contributed to the speech recognition ability of cochlear implant patients; multiple regression analysis showed that postoperative psychophysical percepts such as threshold level (T level), maximum comfortable loudness level (C level), and dynamic ranges (DR) may play an important role in speech recognition ability. In this paper, we focus on determining which intracochlear factors contribute to these postoperative psychophysical percepts of the 22-channel cochlear implant system. We made a three-dimensional (3-D) computer reconstruction 2 from the temporal bone of a cochlear implant patient and measured the following factors: distance between the electrode ring's center and the Rosenthal's canal center (dis); the cross-sectional areas of loose and dense fibrous tissue (lft, dft), their sum, fibrous tissue (ft), and new bone (nb) as inner ear pathologic changes; and the density of residual spiral ganglion cells (sgc). The interrelationship between the postoperative psychophysical percepts and these factors is analyzed and discussed.