Measures of working memory span and verbal rehearsal speed in deaf children after cochlear implantation.
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Large individual differences in spoken word recognition performance have been found in deaf children after cochlear implantation. Recently, Pisoni and Geers (2000) reported that simple forward digit span measures of verbal working memory were significantly correlated with spoken word recognition scores even after potentially confounding variables were statistically controlled for. The present study replicates and extends these initial findings to the full set of 176 participants in the CID cochlear implant study. The pooled data indicate that despite statistical "partialling-out" of differences in chronological age, communication mode, duration of deafness, duration of device use, age at onset of deafness, number of active electrodes, and speech feature discrimination, significant correlations still remain between digit span and several measures of spoken word recognition. Strong correlations were also observed between speaking rate and both forward and backward digit span, a result that is similar to previously reported findings in normal-hearing adults and children. The results suggest that perhaps as much as 20% of the currently unexplained variance in spoken word recognition scores may be independently accounted for by individual differences in cognitive factors related to the speed and efficiency with which phonological and lexical representations of spoken words are maintained in and retrieved from working memory. A smaller percentage, perhaps about 7% of the currently unexplained variance in spoken word recognition scores, may be accounted for in terms of working memory capacity. We discuss how these relationships may arise and their contribution to subsequent speech and language development in prelingually deaf children who use cochlear implants. (+info)
Hierarchical processing in spoken language comprehension.
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Understanding spoken language requires a complex series of processing stages to translate speech sounds into meaning. In this study, we use functional magnetic resonance imaging to explore the brain regions that are involved in spoken language comprehension, fractionating this system into sound-based and more abstract higher-level processes. We distorted English sentences in three acoustically different ways, applying each distortion to varying degrees to produce a range of intelligibility (quantified as the number of words that could be reported) and collected whole-brain echo-planar imaging data from 12 listeners using sparse imaging. The blood oxygenation level-dependent signal correlated with intelligibility along the superior and middle temporal gyri in the left hemisphere and in a less-extensive homologous area on the right, the left inferior frontal gyrus (LIFG), and the left hippocampus. Regions surrounding auditory cortex, bilaterally, were sensitive to intelligibility but also showed a differential response to the three forms of distortion, consistent with sound-form-based processes. More distant intelligibility-sensitive regions within the superior and middle temporal gyri, hippocampus, and LIFG were insensitive to the acoustic form of sentences, suggesting more abstract nonacoustic processes. The hierarchical organization suggested by these results is consistent with cognitive models and auditory processing in nonhuman primates. Areas that were particularly active for distorted speech conditions and, thus, might be involved in compensating for distortion, were found exclusively in the left hemisphere and partially overlapped with areas sensitive to intelligibility, perhaps reflecting attentional modulation of auditory and linguistic processes. (+info)
Cochlear implantation for progressive hearing loss.
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The concept of neural plasticity and the early natural abilities of hearing children to acquire speech and language without instruction have led many authorities to advocate cochlear implantation before the age of 5 years in congenital deafness. Older children therefore become lower priority for scarce public funds because they are perceived to have passed the "window of opportunity" to learn speech, even if hearing is restored, and continue to rely on sign language. This paper shows that a subgroup of congenitally deaf children exists, who, having made good progress with conventional hearing aids, suffer a sudden or progressive hearing deterioration which arrests the speech development. Sixty children have been implanted in the Cambridge Programme, half for meningitis or other acquired losses and half for congenital prelingual deafness. Six of this latter group were congenital but progressive; their progress, deterioration, and improvement after implantation are summarised. (+info)
Comprehension of synthetic speech produced by rule: a review and theoretical interpretation.
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In this paper, we review research on the perception and comprehension of synthetic speech produced by rule. We discuss the difficulties that synthetic speech causes for the listener and the evidence that the immediate result of those difficulties is a delay in the point at which words are recognized. We then argue that this delay in processing affects not only lexical access but also comprehension processes. We consider the mechanisms by which the comprehension system adjusts to this delay, the resulting costs to higher level comprehension processes, and the changes that occur in the language processing system as its familiarity with synthetic speech increases. Based on the framework we have developed, we suggest several directions for future research on the comprehension of synthetic speech. (+info)
Behavioral treatment of children with phonological disorder: the efficacy of vocal imitation and sufficient-response-exemplar training.
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This study examined whether sufficient-response-exemplar training of vocal imitation would result in improved articulation in children with phonological disorder, and whether improved articulation established in the context of vocal imitation would transfer to other verbal classes such as object naming and conversational speech. Participant 1 was 6 years old and attended first grade in a regular public school. Participant 2 was 5 years 4 months old and attended a public kindergarten. Both participants had normal hearing and no additional handicaps. A multiple baseline design across behaviors (target sounds or blends) was employed to examine whether the vocal imitation training resulted in improved articulation. Results showed that both participants improved articulation once training was implemented, and that the improved articulation transferred from vocal imitation to more natural speech such as object naming and conversational speech. Improvement established during training was maintained posttraining and at a 6-month follow-up. (+info)
Defining a left-lateralized response specific to intelligible speech using fMRI.
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Functional imaging studies of language have shown bilateral superior temporal activations in response to 'passive' perception of speech when the baseline condition did not control for the acoustic complexity of speech. Controlling for this complexity demonstrates speech-specific processing lateralized to the left temporal lobe, and our recent positron emission tomography study has emphasized a role for left anterolateral temporal cortex in speech comprehension. This contrasts with the more usual view that relates speech comprehension to left temporal-parietal cortex, the ill-defined area of Wernicke. This study attempted to reconcile these differences, using a more sensitive 3 T functional magnetic resonance imaging system, and a sparse sampling paradigm. We found left lateralized activations for intelligible speech with two distinct foci, one in the anterior superior temporal sulcus and the other on the posterior temporal lobe. Therefore, the results demonstrate that there are neural responses to intelligible speech along the length of the left lateral temporal neocortex, although the precise processing roles of the anterior and posterior regions cannot be determined from this study. (+info)
Self-inflicted cosmetic tongue split: a case report.
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The objective of this case study was to obtain some first-hand information about the functional consequences of a cosmetic tongue split operation for speech and tongue motility. One male patient who had performed the operation on himself was interviewed and underwent a tongue motility assessment, as well as an ultrasound examination. Tongue motility was mildly reduced as a result of tissue scarring. Speech was rated to be fully intelligible and highly acceptable by 4 raters, although 2 raters noticed slight distortions of the sibilants /s/ and /z/. The 3-dimensional ultrasound demonstrated that the synergy of the 2 sides of the tongue was preserved. A notably deep posterior genioglossus furrow indicated compensation for the reduced length of the tongue blade. It is concluded that the tongue split procedure did not significantly affect the participant's speech intelligibility and tongue motility. (+info)
Speech intelligibility of the callsign acquisition test in a quiet environment.
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This paper reports on preliminary experiments aimed at standardizing speech intelligibility of military Callsign Acquisition Test (CAT) using average power levels of callsign items measured by the Root Mean Square (RMS) and maximum power levels of callsign items (Peak). The results obtained indicate that at a minimum sound pressure level (SPL) of 10.57 dBHL, the CAT tests were more difficult than NU-6 (Northwestern University, Auditory Test No. 6) and CID-W22 (Central Institute for the Deaf, Test W-22). At the maximum SPL values, the CAT tests reveal more intelligibility than NU-6 and CID-W22. The CAT-Peak test attained 95% intelligibility as NU-6 at 27.5 dBHL, and with CID-W22, 92.4% intelligibility at 27 dBHL. The CAT-RMS achieved 90% intelligibility when compared with NU-6, and 87% intelligibility score when compared with CID-W22; all at 24 dBHL. (+info)