Treatment generalization from trained /ɹ/ to untrained /l/: a case study of persisting distortion errors

ABSTRACT

The extent to which treatment of speech errors that are phonetic in nature (i.e., distortions) produces generalization to untrained sounds is not well understood. This case study reports a child referred for treatment of a velarized distortion of American English /ɹ/, who also demonstrated an inconsistent velarized distortion of /l/. Acoustic analysis revealed evidence of a covert contrast between /ɹ/ and /l/ prior to treatment. Ultrasound biofeedback treatment and perceptual training targeted /ɹ/ only, but progress was tracked for both /ɹ/ and /l/. Substantial improvements in perceptually rated accuracy and significant changes in acoustic features were observed for both sounds, indicating generalization. These results highlight that generalization from trained to untrained sounds is possible for children with residual speech errors characterized by phonetic distortions.

KEYWORDS:

• Speech sound disorders
• generalization
• covert contrast
• rhotics

Acknowledgments

Research reported in this publication was supported by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health under Award Number R15DC016426 (J. Preston, PI) and R01DC013668 (D. Whalen, PI). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Declaration of interest

The authors report no conflict of interest.

Additional information

Funding

This work was supported by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health [R01DC013668,R15DC016426].