Graeme Clark Collection
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ItemValidation of a technique for establishing maximum comfortable levels for children using cochlear implants [Abstract]( 2002)The aim of fitting a cochlear implant is to establish electrical stimulation parameters that will provide the wearer with comfortable and useful auditory sensations. One parameter that is fundamental to achieving this aim is the Maximum Comfortable Level (C-level). A C-level is the amount of electrical current that produces a loud, but comfortable sound. C-levels need to be established for all channels that a person will use in their speech processor Map. Determining C-levels can be complicated as the person is required to make a judgment about the loudness of a sound. While most adults and older children have the ability to make such a judgment and provide feedback to the clinician, this is rarely the case for young children. Generally, the only way a clinician will be aware a sound could be too loud for a young child is when they observe the child giving an aversive reaction or an involuntary blink. A current level that produces such a reaction is called the Loudness Discomfort Level (LOL). This study examines the relationship between LDLs and C-levels. Testing was performed with a group of adults, using stimulation rates and stimulation modes that are commonly used by children. The LDL/C-level relationship established in this study provides a procedure for selling C-Levels for young children when only loudness discomfort responses can be obtained.
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ItemFactors affecting speech perception outcomes for older children using multichannel cochlear implants( 2002)Experience with cochlear implantation in early-deafened teenagers or young adults has been somewhat disappointing, however, in recent years a proportion of older children have demonstrated excellent speech perception performance. There appears to be a wide gap between the good and poor performers within this group. It is important to investigate the possible factors influencing performance so that adolescents and their families are able to make informed decisions regarding cochlear implant surgery. This study considered a number of factors in a group of 25 children implanted in Melbourne between the ages of 8 and 18 years. Each subject completed open set speech perception testing using BKB sentences before and after implantation and pre-operative language testing using the Peabody Picture Vocabulary Test. Data were collected regarding the type of hearing loss, age at implant, age at hearing aid fitting, audiometric details, and the pre-and postoperative communication mode. Multivariate analysis suggested that three factors have a significant predictive value for post-implant speech perception: pre-operative open-set sentence score, duration of profound hearing loss and equivalent language age. These three factors accounted for 66% of the variance in this group. The results of this study suggest that children who have useful pre-implant speech perception, and higher age-equivalent scores on language measures, would be expected to do well with a cochlear implant. A shorter duration of profound hearing loss is also advantageous. Mean speech perception scores for the older group were not significantly different from younger children.
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ItemWhat factors contribute to successful outcomes for children using cochlear implants( 2000)Long term speech perception data has been collected for 100 children using the Nucleus multichannel cochlear prosthesis in Melbourne. Scores on a number of different assessments are available at approximately six month intervals following implantation for these children. The group represents an unselected sample of cochlear implant users, as all children were included if they had sufficient developmental skills to perform formal speech perception tests. Information was also collected on each child regarding type of hearing loss, age of onset of profound hearing loss, duration of profound hearing loss, age at implantation, pre and post-implant communication mode, developmental delay, speech processing strategy and length of experience with implant use.
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ItemHearing levels and speech perception prior to cochlear implantation - are they predictive of outcomes for adult implant users?( 2000)As the speech perception results obtained for adults using multichannel cochlear implants have improved, people with a wider range of hearing losses are now considering implantation. In the mid-1980s, most adults undergoing cochlear implantation had little or no residual hearing. This made selection and counselling relatively straightforward as any level of hearing obtained through use of the cochlear implant could be considered as a benefit in such cases. Most patients evaluated for implantation today have some degree of useful residual hearing, and may be reliant on this hearing to varying degrees in their everyday life. In essence, they have something to lose if their postoperative performance is poor. In counselling these patients, it would be most helpful to have reliable predictors of postoperative performance. A number of factors such as duration of profound hearing loss, congenital profound hearing loss, and certain aetiologies (eg, head injury) have shown significant links with outcomes in previous studies.