I'm looking for articles on /r/, /l/ and r-controlled vowel substitutions that may have a neurological base. I'm an SLP with a student exhibiting these error sounds that appear to be resistant to change. Thank you for any info you might give me.
There are many aspects of motor speech that may be interfering with the patient's ability to retain a craniofacial form that is adequate to produce a particular phoneme. I believe articulation is heavily dependent on speech airflow and pressure as well as articulatory placement. All of the elements have to be functioning in order to produce phones correctly. Firstly, I would recommend some general articles on motor planning and articulation in order to orient yourself with what is expected in the normal condition. Before considering a neurogenic etiology, I would first determine if the patient has the capacity to produce the sound with the correct tongue position (retroflexing toward palate), appropriate airflow and pressure required to produce /r/ (airflow would be fairly high as it is produced with an open mouth and not being occluded by much except the tongue in part). Pressure would be low but necessary for adequate production. If you are finding that the patient's physiological responses seem adequate for production then you may consider a neurogenic etiology. When completing a phonemic inventory, are there similar sounds in the class that are difficult? If so, it may be a matter of starting some oral motor exercises that may help with general articulator strength improvement.
Whether or not oral motor exercises can translate into connected speech is another matter, but it may be worth the effort. You may want to look into other symptoms that may suggest a neurogenic etiology. Have you considered the link between auditory processing and phonologic delay/disorder?
Title: Auditory Processing and Phonologic Disorder
Source: Audiology : official organ of the International Society of
Audiology. 35, no. 1, (1996): 37 (8 pages)
Additional Info: S. Karger,
Title: Motor planning center for speech articulation in the normal human brain
Source: Neuroreport. 10, no. 4, (1999): 765
Additional Info: Rapid Communications of Oxford Ltd.,
Dr. Bridget A. Russell received her B.A., M.A., and Ph.D. from the State University of New York at Buffalo. Since that time she has been employed as an Associate Professor at the State University of New York College at Fredonia. Her main research interests are professional voice, and voice/respiratory disorders affecting speech production. She has published works in JSHLR and Voice and Speech Review and has served as editorial consultant for JSHLR. She is director of the Speech Production Laboratory at SUNY College at Fredonia and is currently researching the efficacy of voice therapy with patients at the Voice Center of Western New York.