Speech perception abilities of adults with dyslexia: is there any evidence for a true deficit?

PURPOSE: This study investigated whether adults with dyslexia show evidence of a consistent speech perception deficit by testing phoneme categorization and word perception in noise. METHOD: Seventeen adults with dyslexia and 20 average readers underwent a test battery including standardized reading, language and phonological awareness tests, and tests of speech perception. Categorization of a pea/bee voicing contrast was evaluated using adaptive identification and discrimination tasks, presented in quiet and in noise, and a fixed-step discrimination task. Two further tests of word perception in noise were presented. RESULTS: There were no significant group differences for categorization in quiet or noise, across- and within-category discrimination as measured adaptively, or word perception, but average readers showed better across- and within-category discrimination in the fixed-step discrimination task. Individuals did not show consistent poor performance across related tasks. CONCLUSIONS: The small number of group differences, and lack of consistent poor individual performance, suggests weak support for a speech perception deficit in dyslexia. It seems likely that at least some poor performances are attributable to nonsensory factors like attention. It may also be that some individuals with dyslexia have speech perceptual acuity that is at the lower end of the normal range and exacerbated by nonsensory factors

The relationship of phonological ability, speech perception, and auditory perception in adults with dyslexia

This study investigated whether auditory, speech perception and phonological skills are tightly interrelated or independently contributing to reading. We assessed each of these three skills in 36 adults with a past diagnosis of dyslexia and 54 matched normal reading adults. Phonological skills were tested by the typical threefold tasks, i.e. rapid automatic naming, verbal short term memory and phonological awareness. Dynamic auditory processing skills were assessed by means of a frequency modulation (FM) and an amplitude rise time (RT); an intensity discrimination task (ID) was included as a non-dynamic control task. Speech perception was assessed by means of sentences and words in noise tasks. Group analysis revealed significant group differences in auditory tasks (i.e. RT and ID) and in phonological processing measures, yet no differences were found for speech perception. In addition, performance on RT discrimination correlated with reading but this relation was mediated by phonological processing and not by speech in noise. Finally, inspection of the individual scores revealed that the dyslexic readers showed an increased proportion of deviant subjects on the slow-dynamic auditory and phonological tasks, yet each individual dyslexic reader does not display a clear pattern of deficiencies across the levels of processing skills. Although our results support phonological and slow-rate dynamic auditory deficits which relate to literacy, they suggest that at the individual level, problems in reading and writing cannot be explained by the cascading auditory theory. Instead, dyslexic adults seem to vary considerably in the extent to which each of the auditory and phonological factors are expressed and interact with environmental and higher-order cognitive influences

Children's naming and word-finding difficulties: descriptions and explanations

Purpose: There are a substantial minority of children for whom lexical retrieval problems impede the normal pattern of language development and use. These problems include accurately producing the correct word even when the word?s meaning is understood; such children are often referred to as having word-finding difficulties (WFDs). This review examines the nature of naming and lexical retrieval difficulties in these and other groups of children. Method: A review of the relevant literature on lexical access difficulties in children with word finding difficulties was conducted. Studies were examined in the terms of population parameters and comparison groups included in the study. Results and Conclusions: Most discussions of the cognitive processes causing lexical retrieval difficulties have referred to semantics, phonology and processing speed. It is argued that our understanding of these topics will be further advanced by the use of appropriate methodology to test developmental models that both identify the processes in successfully performing different lexical retrieval tasks and more precisely locating the difficulties experienced by children with such tasks

The relationship between motor control and phonology in dyslexic children

Background: The goal of this study was to investigate the automaticity/cerebellar theory of dyslexia. We tested phonological skills and cerebellar function in a group of dyslexic 8-12 year old children and their matched controls. Tests administered included the Phonological Assessment Battery, postural stability, bead threading, finger to thumb and time estimation. Results: Dyslexic children were found to be significantly poorer than the controls at all tasks but time estimation. About 75% of dyslexics were more than one standard deviation below controls in phonological ability, and 50% were similarly impaired in motor skills. However, at least part of the discrepancy in motor skills was due to dyslexic individuals who had additional disorders (ADHD and/or DCD). The absence of evidence for a time estimation deficit also casts doubt on the cerebellar origin of the motor deficiency. About half the dyslexic children didn't have any motor problem, and there was no evidence for a causal relationship between motor skills on the one hand and phonological and reading skills on the other. Conclusion: This study provides partial support for the presence of motor problems in dyslexic children, but does not support the hypothesis that a cerebellar dysfunction is the cause of their phonological and reading impairment

Predicting future reading problems based on pre-reading auditory measures: a longitudinal study of children with a familial risk of dyslexia

Purpose: This longitudinal study examines measures of temporal auditory processing in pre-reading children with a family risk of dyslexia. Specifically, it attempts to ascertain whether pre-reading auditory processing, speech perception, and phonological awareness (PA) reliably predict later literacy achievement. Additionally, this study retrospectively examines the presence of pre-reading auditory processing, speech perception, and PA impairments in children later found to be literacy impaired. Method: Forty-four pre-reading children with and without a family risk of dyslexia were assessed at three time points (kindergarten, first, and second grade). Auditory processing measures of rise time (RT) discrimination and frequency modulation (FM) along with speech perception, PA, and various literacy tasks were assessed. Results: Kindergarten RT uniquely contributed to growth in literacy in grades one and two, even after controlling for letter knowledge and PA. Highly significant concurrent and predictive correlations were observed with kindergarten RT significantly predicting first grade PA. Retrospective analysis demonstrated atypical performance in RT and PA at all three time points in children who later developed literacy impairments. Conclusions: Although significant, kindergarten auditory processing contributions to later literacy growth lack the power to be considered as a single-cause predictor; thus results support temporal processing deficits’ contribution within a multiple deficit model of dyslexia

Neurovisual training (TRIGRAM) in young patients with visual-perceptive dyslexia

Dyslexia is a language-based learning disability. Although this condition is characterized by anatomical malformation of the brain, it seems that the typical reading pattern of dyslexic may be also related to more complex sensory deficits. Among them, visual- perceptive deficits have been described in a subtype of dyslexia, called visual-perceptive dyslexia. The distinctive feature of a patient suffering from visual-perceptive dyslexia form is marked by effortlessly recognize the characteristics of each individual stimulus. The Tetra protocol is a visual-perceptual evaluation protocol that was introduced for the diagnostic phase and the rehabilitation of visual-perceptive dyslexia. The diagnostic tests include: the eidomorphometry test, designed to evaluate the perception of spatial relationships; the contrast sensitivity threshold test, especially at low spatial frequencies; and the REPORT TEST words, to assess the speed and the reading efficiency. In addition, the rehabilitation phase is carried out with the visual neuro-enhancement program TRIGRAM, a visual training proposal designed to reduce the lateral masking phenomenon in visual-perceptive dyslexic. Thus, in this study we used the diagnostic tests of TETRA® Protocol to determine presence of visual-perceptual abnormalities in children with dyslexia. Proven time the presence of these visual-perceptual alterations, the patients were also subjected to the rehabilitation sessions of TRIGRAM, in order to investigate whether this visual training may improve the pattern of reading. At the end of the program (t1) and after three months (t2), the same subjects underwent the same diagnostic tests of TETRA® Protocol to evaluate and confirm the results obtained during rehabilitation program. The results showed a significant increase in contrast sensitivity at low and high spatial frequencies. Moreover, the same improvements in the visual system's ability to discriminate the contours of an object within the field of view, have been maintained three months after the end of treatment. We also observed a significant improvement in the perception of spatial relationships, with reduction of SRA value. In conclusion, this study demonstrates that the visual rehabilitation training (TRIGRAM) is able to improve the perception of spatial relationships, and increase contrast sensitivity in young patients affected by "visual dyslexia". Nonetheless, these data need to be confirmed in larger cohort of subjects in order to establish whether these effects can also increase lexical ability (increased reading speed and reduce errors during the lexical task)

Tech for Understanding: An Introduction to Assistive and Instructional Technology in the Classroom

This paper examines the different types of assistive and instructional technology available to students who are classified with one or more of the thirteen disabilities outlined in the Individuals with Disabilities Education Act (referred to as, IDEA). While the roles of assistive and instructional technology are different, there are many instances where their uses may overlap. Thus, while these two categories will be discussed separately, it should be noted that some information may be applied to each category and more than one piece of technology. The purpose of this paper is to provide an introduction to the world of assistive and instructional technology for those who may be new to its concepts, particularly parents who have recently learned that their child may benefit from extra assistance and future educators who are interested in learning more about the devices they will be using to reach their students. Each of the thirteen disabilities will be discussed briefly, and then each disability will be assigned several types of assistive and instructional technology that serve it well. This will by no means be an exhaustive list of all types of technology available to teachers, parents, and students. However, it will attempt to provide a varied glimpse at some of the options that are available and how they may help children who are struggling to access the curriculum

Revisiting the "enigma" of musicians with dyslexia:Auditory sequencing and speech abilities

Previous research has suggested a link between musical training and auditory processing skills. Musicians have shown enhanced perception of auditory features critical to both music and speech, suggesting that this link extends beyond basic auditory processing. It remains unclear to what extent musicians who also have dyslexia show these specialized abilities, considering often-observed persistent deficits that coincide with reading impairments. The present study evaluated auditory sequencing and speech discrimination in 52 adults comprised of musicians with dyslexia, nonmusicians with dyslexia, and typical musicians. An auditory sequencing task measuring perceptual acuity for tone sequences of increasing length was administered. Furthermore, subjects were asked to discriminate synthesized syllable continua varying in acoustic components of speech necessary for intra-phonemic discrimination, which included spectral (formant frequency) and temporal (voice onset time (VOT) and amplitude envelope) features. Results indicate that musicians with dyslexia did not significantly differ from typical musicians and performed better than nonmusicians with dyslexia for auditory sequencing as well as discrimination of spectral and VOT cues within syllable continua. However, typical musicians demonstrated superior performance relative to both groups with dyslexia for discrimination of syllables varying in amplitude information. These findings suggest a distinct profile of speech processing abilities in musicians with dyslexia, with specific weaknesses in discerning amplitude cues within speech. Since these difficulties seem to remain persistent in adults with dyslexia despite musical training, this study only partly supports the potential for musical training to enhance the auditory processing skills known to be crucial for literacy in individuals with dyslexia