Graeme Clark Collection

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Start date: 1990 × End date: 1999 × Subject: speech perception × Subject: otology × Type: Journal Item ×

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    The importance of different frequency bands to the speech perception of cochlear implantees [Abstract]
    Henry, Belinda A. ; McKay, Colette M. ; McDermott, Hugh J. ; Clark, Graeme M. ( 1996)
    It is well known that cochlear implantees exhibit a wide range of speech perception ability. Understanding the reason for this variability may lead to improved speech processors. This study investigates whether implantees rely on different areas of the speech spectrum for speech cues, compared to normally hearing listeners, and whether poor performers rely on different spectral areas than better performers. Six subjects with the Mini System 22 implant and using the SPEAK strategy participated in this experiment. Scores for monosyllabic words were obtained using the full speech spectrum and with selected frequency bands removed from the subjects’ speech processor maps. The Articulation Index (AI) is a measure of the proportion of speech information available to a listener, and the relative contribution to AI from different frequency bands is termed the Importance Function. The five frequency bands studied in this experiment were determined to be of equal importance to normally hearing listeners for the speech material used. The scores for each implantee were transformed into AI values, and hence the relative importance of the bands was determined. This relative importance was compared between the implantee group and normally hearing listeners to determine the way in which speech perception by electrical stimulation varies from that by acoustical stimulation. Comparisons were also made between individual implantees to determine whether correlations exist between their speech perception ability and their use of cues in different parts of the spectrum. Further research will determine whether the differences among implantees are correlated with their ability to perceive changes in stimulation place or temporal characteristics.
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    Speech perception in children following habilitation with background noise [Abstract]
    Cowan, R. S. C. ; Klieve, S. ; Galvin, K. L. ; Sarant, J. Z. ; Clark, Graeme M. ( 1996)
    Recent evaluation of open-set work and sentence perception results for a group of children evaluated over a two year period showed that improvements to speech perception scores in poor signal-to-noise conditions were possible with use of the Speak speech processing strategy. The increases were noted particularly in speech perception in poor signal-to-noise conditions. However, overall scores were still lower that for hearing in quiet. As children are often in noisy environments, it was of interest to assess whether specific habilitation involving perception in controlled background noise could improve perception. A preliminary study evaluating perception of open-set words and sentences in background noise for four children has been completed. Each of the children was assessed over a six month period, using repeated assessments of connected discourse tracking, and word and sentence perception scores. At each assessment, measures were made both in quiet and in background noise. The specific signal-to-noise ration varied with each child, but was kept constant through the evaluation. During the six month period, children had weekly habilitation sessions, which included specific perceptual training in controlled background noise. Preliminary results indicate that training in ‘controlled noise’ can significantly improve speech perception results for this group of children.