Infant Speech Development
The human infant produces a great variety of nonreflexive sounds during the first six months of life but it is not until the seventh month, on average, that the infant begins to produce syllables that are perceived by the adult listener to be speech-like in form. These canonical syllables are sometimes mistaken for meaningful speech but in fact the infant practices their production in unmeaningful strings called babble for another 5 months before the first word usually appears. It is now know that the emergence of canonical babble is not simply a matter of maturational processes involving articulatory structure or neurophysiological development. Access to speech input is essential but the learning mechanisms that account for the impact of environmental inputs on early speech learning are not yet clear. What are the learning mechanisms that account for the emergence of canonical syllables at 7 months? What is the infant learning while practicing these syllables throughout the canonical babble stage of vocal development? We are exploring the answers to these questions in studies involving infants and their mothers.
In the past we have published studies indicating that infants learning English and French do not babble in the same way (Rvachew, Alhaidary, Mattock, & Polka, 2008; Rvachew, Mattock, Polka, & Ménard, 2006). More recently we have found that Arabic-learning infants (8 through 18 months of age) achieve a larger vowel space in their babble at an earlier age than English- and French-learning infants (Alhaidary & Rvachew, submitted). One mechanism for language specific babbling might be mothers’ mimicry of their infants’ speech-like utterances. Doctoral student Pegah Athari has found that patterns of maternal mimicry support exploration in the earliest stages of speech development versus exploitation as the infant approaches the word learning stage. In other words, the mothers support a high rate of variable responding during the early part of the canonical babble stage; subsequently, maternal mimicry stabilizes patterns that correspond to potential meaningful words. In future studies we will consider learning models that posit an interplay of self-supervised learning and reinforcement. We will also extend the research to Arabic-learning infants with normal and impaired hearing.
TASC Project
In this project we are attempting to classify children with very severe primary speech delay as having difficulties that are primarily in the area of phonological planning versus those who are having difficulties that are primarily in the area of motor planning (i.e., childhood apraxia of speech). We are using the Syllable Repetition Test, the Diagnostic Evaluation of Articulation and Phonology and Maximum Performance Tasks to make this differentiation. Then, using a single subject randomization design we are comparing the relative effectiveness of an intervention that focuses on phonological planning versus auditory motor integration for children with these two types of planning difficulties. So far the results are suggesting that these types of planning difficulties can be differentiated although there is often overlap between difficulties with encoding, phonological memory and transcoding (i.e., motor planning) within children. Furthermore, individual children do respond differentially to the distinct interventions that we are using. Staring in the spring of 2015 we will be incorporating ultrasound as an intervention tool into this project. We will also be expanding the project to include older children with residual speech errors as well as children with Down Syndrome.
This project has received support from the Childhood Apraxia of Speech Association of North America and by the Ruth Ratner Miller Foundation.
Links:
https://developmentalphonologicaldisorders.wordpress.com/2015/08/15/using-orthographic-representations-in-speech-and-language-therapy/
The Down Syndrome Project
This project investigates speech therapy for individuals with Down syndrome and Apraxia of Speech. By comparing three different therapy protocols, our aim is to discover which is the most effective for both learning and generalization for the individual. Diversity is the norm within the population of individuals with Down syndrome, and part of this study seeks to identify whether a specific psycholinguistic profile, measured by tests, consistently aligns with a particular treatment protocol. Should this be the case, we will be one step closer to understanding the most efficient and effective treatment for these individuals.
The ECRIP Project
Children who present with a phonological disorder misarticulate more speech sounds than other children their age. They also have poorer speech perception abilities and phonological awareness abilities than their peers and are more at risk of presenting with reading difficulties. The objective of the research project was to test the relative efficacy of different combinations of three intervention components (individual therapy, home program and small group intervention) to improve speech production accuracy and phonological awareness skills in francophone children with a developmental phonological disorder. We found that the children responded very well to a combination of treatments that involved surprisingly little direct speech practice when all elements were implemented in a coherent fashion, specifically (input oriented individual speech therapy using the procedures focused stimulation, auditory bombardment, error detection tasks, and minimal pairs therapy; small group therapy targeting phonological awareness (teaching implicit knowledge of syllables, onsets and rimes); and a parent group intervention (teaching dialogic reading techniques). The intervention was implemented over a 12 week period with the individual treatment occurring first and the two group interventions following in the second 6 week block.
This randomized control trial was funded by a Social Sciences and Humanities Council of Canada grant to Dr. Susan Rvachew. The project was coordinated by Françoise Brosseau-Lapré, Ph.D., S-LP(c) who was supported by a doctoral fellowship from le Fonds de la Recherche en Santé du Québec. Dr. Brosseau-Lapré is currently an Assistant Professor at Purdue University.
The results of this study have been described in published papers, blogs, podcasts and many conference papers. Some useful links are as follows:
“A randomized trial of twelve-week interventions for the treatment of developmental phonological disorder in francophone children” (published report and complete procedure manual)
Scatterplots and Speech therapy (open access blogpost describing the trial results)
Testing Combinations of Phonological Intervention Approaches for Francophone Children (A “Behind the Science” Podcast)
The Digital Media Partnership
Click here for a link to the Digital Media Partnership blog.