Children with speech sound disorders make up one of the largest proportions of school-based speech-language pathologists’ caseloads. Yet the variety of error patterns make “one size fits all” treatment and assessment procedures difficult to find. Therefore, pinpointing the most effective and efficient assessment and treatment measures is of key importance. The goal of my research program is to improve our understanding of speech sound disorders and develop more effective treatment and assessment methods. Within my program of research, there are two relevant themes. One focuses on translational questions related to treatment effectiveness and efficiency. The other theme focuses on theoretical questions related to knowledge of speech sounds.

In addressing the first theme of treatment effectiveness and efficiency, my ongoing project entitled Age as a factor in the acquisition of late-acquired sounds is intended to locate the age at which treatment for notoriously difficult late-acquired sounds, such as /r/, is most effective and efficient. Previous research has shown that children in the preschool years are at an accelerated period of learning speech sounds, and children who are age 7-8 are in the midst of a learning plateau. Typically, late-acquired sounds are treated at the expected age of acquisition (e.g. 7-8), and therefore the opportunity to take advantage of the accelerated period of growth in ages 4-5 is missed. Waiting for the expected age of acquisition may result in broader impacts including persistent speech sound errors, difficulty with phonological awareness, and difficulty acquiring language. This study seeks to establish proof of concept that treating late-acquired sounds at an earlier age yields faster and more accurate acquisition of these sounds. In a single-subjects repeated multiple baselines design, children in two age groups (4-5 and 7-8) are provided an evidence-based speech therapy program for late acquired sounds. Their treatment targets are either /r/ or /θ/. How well each group learns their treatment targets will be determined based on accuracy and acoustic measures, and how quickly each group learns their treatment targets will be determined based on number and length of sessions to meet criterion. The results of this study will provide practicing speech therapists with evidence to either support the current practice of waiting for the developmental age of acquisition, or evidence that will shift the way services for speech sound disorders are delivered. Moreover, this study may establish proof of concept that younger children are primed for learning even the most difficult sounds of the English sound system. This data will serve as pilot data to support applications for funding of a larger scale clinical trial.

To address the theme of understanding speech sound knowledge, I have conducted a series of studies to better understand children’s word identification in the face of speech sound substitutions to answer a question that marries speech sound knowledge with word recognition and speech perception. I played preschoolers minimal triplets of words. These words were accurately produced (e.g. “leaf”), misarticulated with a common substitution (e.g. “weaf”), and misarticulated with an uncommon substitution (e.g. “yeaf”). Preschoolers were then asked to identify these words as either real or novel objects by selecting either a picture of a real object (e.g. a leaf) or a novel object. Real object selections, response time and “certainty” were measured using MouseTracker software (in two experiments) and an eye-tracker (in a third experiment). Results across these studies showed that children’s word identification is impacted by the commonality of a misarticulation, but that processing may be negatively impacted—particularly in conditions where the speech sound substitution is familiar. These results revealed a degree of flexibility in children’s speech perception and recognition of words that may assist in day-to-day peer interactions. These findings have been submitted for publication to the Journal of Speech Language Hearing Research, and an additional pair of experiments in this line of work are in preparation for submission. I intend to continue addressing questions such as this one by investigating underlying representations of phonemes through a similar word recognition paradigm, and examining the differences in phonological acceptability in typical and disordered populations.

The work I have done and plan to continue will contribute to the overall understanding of speech sound acquisition in both typical and disordered populations by addressing theoretically relevant questions to guide clinically meaningful answers.