Mark Leddy

Bio: Mark Leddy is an academic researcher from National Science Foundation. The author has contributed to research in topics: Intelligibility (communication) & Vowel. The author has an hindex of 5, co-authored 6 publications receiving 217 citations.

Improving the communication of people with Down syndrome

Abstract: "An excellent resource for families and professionals, [it] offers helpful advice throughout. Research shows that the more children are able to communicate and interact with their environments, the more quickly they will develop overall. This critical volume provides a framework for assessing and treating speech, language, and communication problems in children and adults with Down syndrome. The book offers valuable guidelines for assessing comprehension and production abilities, promoting language learning, and alleviating communication difficulties. For speech-language pathologists, clinicians, educators, researchers, and AAC specialists, this resource helps practitioners better evaluate and treat communication disorders in people with Down syndrome.

An evaluation of articulatory working space area in vowel production of adults with Down syndrome.

Abstract: Many adolescents and adults with Down syndrome have reduced speech intelligibility. Reasons for this reduction may relate to differences in anatomy and physiology, both of which are important for creating an intelligible speech signal. The purpose of this study was to document acoustic vowel space and articulatory working space for two adult speakers with Down syndrome who had reduced speech intelligibility (mean = 56% based on single words). Articulatory data for the tongue were collected using a real-time flesh-point tracking method (i.e. X-ray microbeam). Results show smaller F1–F2 acoustic vowel space area for both speakers with Down syndrome compared with the control speakers. Reduced articulatory working space area and slower movement speed were also found for three of the four tongue points analysed. Although generalizations are limited by the small number of participants, findings warrant further investigation of the underlying articulatory characteristics of speech production for individuals with...

Technology to Advance High School and Undergraduate Students with Disabilities in Science, Technology, Engineering, and Mathematics.

Abstract: Americans with disabilities are underemployed in science, technology, engineering and mathematics (STEM) at higher rates than their nondisabled peers. This article provides an overview of the Natio...

Phonetic Intelligibility Testing in Adults with Down Syndrome

Abstract: The purpose of the study was to document speech intelligibility deficits for a group of five adult males with Down syndrome, and use listener based error profiles to identify phonetic dimensions underlying reduced intelligibility. Phonetic error profiles were constructed for each speaker using the Kent, Weismer, Kent, and Rosenbek (1989) word intelligibility test. The test was designed to allow for identification of reasons for the intelligibility deficit, quantitative analyses at varied levels, and sensitivity to potential speech deficits across populations. Listener generated profiles were calculated based on a multiple-choice task and a transcription task. The most disrupted phonetic features, across listening task, involved simplification of clusters in both the word initial and word final position, and contrasts involving tongue-posture, control, and timing (e.g., high-low vowel, front-back vowel, and place of articulation for stops and fricatives). Differences between speakers in the ranking of these phonetic features was found, however, the mean error proportion for the six most severely affected features correlated highly with the overall intelligibility score (0.88 based on multiple-choice task, .94 for the transcription task). The phonetic feature analyses are an index that may help clarify the suspected motor speech basis for the speech intelligibility deficits seen in adults with Down syndrome and may lead to improved speech management in these individuals.

Children with Disabilities: A Longitudinal Study of Child Development and Parent Well-Being.

Abstract: This Monograph presents the results of the Early Intervention Collaborative Study, a longitudinal investigation of the cognitive and adaptive behavior development of children with developmental disabilities and the adaptation of their parents, extending from infancy through middle childhood. The study was designed to generate and test conceptual models of child and family development and contribute to the knowledge base that informs social policy and practice. The sample for the investigation reported here consists of 183 children with Down syndrome, motor impairment, developmental delay and their families who were recruited at the time of their enrollment in an early intervention program in Massachusetts or New Hampshire. Data were collected at five time points between entry to early intervention and the child's 10th birthday. Home visits were conducted at each time point and included child assessments, maternal interview, and questionnaires completed independently by both parents. Trajectories in children's development and parental well-being were analyzed using hierarchical linear modeling. Predictor variables were measured at age 3 years when children were exiting early intervention programs. Children's type of disability predicted trajectories of development in cognition, social skills, and daily living skills. Children's type of disability also predicted changes in maternal (but not paternal) child-related and parent-related stress. Beyond type of disability, child self-regulatory processes (notably behavior problems and mastery motivation) and one aspect of the family climate (notably mother-child interaction) were key predictors of change in both child outcomes and parent well-being. A different aspect of the family climate--family relations--also predicted change in child social skills. Parent assets, measured as social support and problem-focused coping, predicted change in maternal and paternal parent-related stress respectively. The implications of these findings for both the science of child development and the policies and practices of developmental intervention are discussed.

Language development in Down syndrome: From the prelinguistic period to the acquisition of literacy

Abstract: Down syndrome (DS) is associated with abnormalities in multiple organ systems and a characteristic phenotype that includes numerous behavioral features. Language, however, is among the most impaired domains of functioning in DS and, perhaps, also the greatest barrier to independent meaningful inclusion in the community. In this article, we review what is known about the extent, nature, and correlates of the language and related problems of individuals with Down syndrome. In doing so, we focus largely on the syndrome-specific features of the language phenotype, although we also consider within-syndrome variation. The review focuses on the prelinguistic foundations of language and the major components of language (i.e., vocabulary, syntax, and pragmatics). We also consider two topics in the treatment and education of individuals with DS: prelinguistic communication intervention and the acquisition of literacy skills.

Language and communication development in Down syndrome.

Abstract: Although there is considerable variability, most individuals with Down syndrome have mental retardation and speech and language deficits, particularly in language production and syntax and poor speech intelligibility. This article describes research findings in the language and communication development of individuals with Down syndrome, first briefly describing the physical and cognitive phenotype of Down syndrome, and two communication related domains—hearing and oral motor skills. Next, we describe language development in Down syndrome, focusing on communication behaviors in the prelinguistic period, then the development of language in children and adolescents, and finally language development in adults and the aging period. We describe language development in individuals with Down syndrome across four domains: phonology, semantics, syntax, and pragmatics. Wethen suggest strategies for intervention and directions for research relating to individuals with Down syndrome. © 2007 Wiley-Liss, Inc. MRDD Research Reviews 2007;13:26–35.

Language Characteristics of Individuals with Down Syndrome

Abstract: On average, language and communication characteristics of individuals with Down syndrome (the most common genetic cause of intellectual disability) follow a consistent profile. Despite considerable individual variability, receptive language is typically stronger than expressive language, with particular challenges in phonology and syntax. We review the literature on language and literacy skills of individuals with Down syndrome, with emphasis on the areas of phonology, vocabulary, syntax, and pragmatics. We begin by describing the hearing, oral-motor, cognitive, social, and prelinguistic and early nonverbal communication characteristics of individuals with Down syndrome. We conclude with a discussion of clinical implications and research directions.