Date of Award

5-2026

Degree Type

Creative Project

Degree Name

Master of Science (MS)

Department

Communicative Disorders and Deaf Education

Committee Chair(s)

Annalise R. Fletcher

Committee

Annalise R. Fletcher

Committee

Juliet Weinhold

Committee

Brittan Barker

Committee

Bobbie Liechty

Abstract

Purpose: 

This study examined longitudinal changes in /ɹ/ production (i.e., the “r” sound) among 14 children aged five to seven at risk for persistent speech sound disorders (SSDs). Children at risk for SSDs show slower or atypical development of /ɹ/, yet little is known about which early patterns predict persistent difficulty, making it difficult for clinicians to prioritize caseloads and provide timely intervention. Using perceptual accuracy ratings across varied /ɹ/ contexts, we modeled growth in /ɹ/ accuracy across different word contexts and evaluated the extent to which early accuracy and changes in /ɹ/production predicted mastery at age seven.

Methods: 

Longitudinal recordings of children with rhotic errors were analyzed to examine perceptual changes in /ɹ/ productions. These productions, containing words and non-words with prevocalic /ɹ/ as well as the isolated vocalic ‘er’ sound, were rated for accuracy by two listener groups: trained speech pathologists and SLP master's students (n = 38) and naïve, inexperienced adult listeners (n = 244). A logistic regression was used to assess whether baseline accuracy predicted later mastery. Following this, linear mixed-effects models were utilized to evaluate longitudinal growth trajectories and examine how phonetic context and age influenced accuracy ratings.

Results: 

The logistic regression indicated that initial baseline accuracy at age five did not significantly predict eventual acquisition of the phoneme. However, linear mixed-effects modeling revealed that longitudinal growth trajectories effectively differentiated the groups; children who eventually acquired /ɹ/ demonstrated an average perceptual accuracy increase of approximately 2.1% per month. In contrast, children who did not acquire the sound exhibited a significantly flatter growth curve, improving by only about 0.2% per month. There were also differences in acquisition patterns across phonetic contexts. The acquired group showed significantly higher early accuracy in vocalic /ɹ/ compared to prevocalic contexts, and their longitudinal growth rate for vocalic /ɹ/ was flatter compared to their prevocalic growth over the same timeframe. Furthermore, while trained clinicians demonstrated higher inter-rater reliability in their ratings of accuracy than inexperienced listeners, statistical analyses of both listener datasets yielded almost identical developmental trajectories of accuracy across speakers.

Conclusions: 

Through longitudinal rating of children’s /ɹ/ productions, this study identified patterns in the trajectory of acquisition, clearly delineating children who did and did not acquire the sound. This provides a compelling argument for the use of longitudinal tracking to determine which children ought to be prioritized for intervention services and which may acquire the sound independently. Our analysis also demonstrated no significant difference in accuracy ratings between experienced listeners and inexperienced listeners when taken in aggregate, mirroring how both listener groups may perceive the child in a naturalistic setting and emphasizing the potential impact of SSDs when these errors are so readily identified by inexperienced listeners. Finally, our results suggest that the prevocalic /ɹ/ context is the most suitable for determining acquisition due to its lower initial accuracy and more defined rate of change.

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