Browsing by Subject "Perceptual disorders"
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Item The role of central auditory processing in attention-deficit/hyperactivity disorder : a neuropsychological investigation(2006-05) Suess, Cressida Evelyn, 1976-; Semrud-Clikeman, MargaretCentral Auditory Processing Disorder (CAPD) is defined as a modality-specific perceptual dysfunction that is not due to peripheral hearing impairment (McFarland & Candace, 1995). It may include limitations in the ongoing transmission, analysis, transformation, elaboration, storage, retrieval and use of auditory stimuli. CAPD has also been reported to be associated with difficulties in memory, reading, spelling, language, and attention. The broad conceptualization of CAPD has contributed to difficulty in the diagnosis and treatment of children who present with auditory processing impairment. A major concern related to the lack of specificity in the definition of CAPD is the inclusion of attention. The clinical overlap in CAPD and ADHD has led to research questions regarding the validity of CAPD as a distinct disorder. Participants were 30 children aged eight to 14 re-recruited from a larger study investigating social competence in ADHD. They were asked to volunteer to complete additional measures of attention and auditory processing. Prior to participating they had completed the Behavioral Assessment System for Children- Parent Rating Scale (BASCPRS) and the SIDAC. The BASC was used as measure of externalizing behavior and the SIDAC was used to classify participants into subtypes of ADHD. Participants completed the SCAN (Keith, 1995) as a measure of auditory processing and the Tests of Variables of Attention- Auditory (T.O.V.A.-A.) as a measure of attention. Participants were placed into groups based on their subtype of ADHD. There were two groups including ADHD/PI and a collapsed group including ADHD/combined and ADHD/HI. Discriminant function analysis was used to determine the accuracy of classification into subtypes using combinations of the predictor variables. Results of the analyses indicated that externalizing behavior was the most robust predictor variable, with an accuracy rate of 80 percent. Including auditory processing and auditory attention did not improve the classification rate. When used alone as a predictor variable, auditory processing was not found to not be effective in classifying participants. Results have research and clinical implications. Sensitivity and specificity issues related to the measures used are discussed. Recommendations for future research are offered.Item Vowel targeting and perception in apraxia of speech(2006) Jacks, Adam Patrick; Marquardt, Thomas P.Vowel production and perception were examined as a window on speech motor control processes in five adults with acquired apraxia of speech (AOS) and five nonbrain-damaged (NBD) control participants. Articulatory targeting for vowels was assessed acoustically for the three front vowels [ɪ], [ɛ], and [æ] in four stimulus conditions varying in word length. Vowels were produced in a normal, unconstrained context and in two bite block conditions, where the mouth opening was controlled by placing a small or large piece of plastic between the teeth. Vowel perception for front vowels was tested using standard categorical tests of identification and same-different discrimination. Processing of vowel information also was assessed in tests of rhyme generation and judgment. Acoustic analysis of apraxic vowel production revealed formant frequencies within normal ranges. Introduction of the bite block constraint destabilized vowel targeting for both apraxic and normal participants, resulting in greater targeting error and reduced distinctiveness between adjacent vowels in the vowel space. Vowel formants in multisyllabic words varied from those produced in monosyllables for both groups, although these deviations were perceived as normal variation by listeners. Although apraxic vowel formants generally conformed to normal ranges, perceptual goodness ratings indicated poorer perceived quality of apraxic vowels compared to NBD controls, and measures of vowel targeting accuracy and vowel distinctiveness also were consistently inferior for apraxic speakers. Perceptual testing revealed normal vowel discrimination in all AOS participants, while four of five apraxic listeners had inconsistent ability to identify vowels. Comparison of production and perception measures indicated no significant relationship between abilities in the two domains for AOS or NBD participants. Distinctiveness of produced vowels was significantly related to clinical measures of speech deficits in apraxia, while perceptual deficits were correlated with auditory comprehension scores. Findings suggest that vowel production in AOS is characteristic of a motor targeting deficit, although variability of vowel formants has a minor effect on the overall communicative impairment in people with the disorder. The lack of correspondence between production and perception abilities indicates that perceptual processing is not a major factor in the motor targeting abilities of individual with AOS.