Effects of Limited or Excessive Jaw Mobility During Conversational Speech

Posted by Deborah Grauzam on

by Sara Rosenfeld-Johnson

This presentation was made at the 2015 annual ASHA Convention, Session #1080.


Practicing Speech-Language Pathologists report that many clients demonstrate limited or excessive up-and-down jaw movements during communication as compared to their typically developing peers.  The results of this retrospective study suggest that atypical jaw skills are related to deficits in speech clarity in clients diagnosed with multiple articulation disorder and dysarthria.


Practicing Speech-Language Pathologists report that many clients, with diagnosed multiple articulation disorders, demonstrate limited or excessive up-and-down jaw movements during communication as compared to their typically developing peers.  The focus of this retrospective study was to determine if children and adults, diagnosed with multiple articulation disorders, were using the jaw heights needed to allow the tongue and lips to move independently for consonant and vowel productions on the conversational level. “Individual differences in jaw movement are real and often large; and the jaw is, in a real sense a primary articulator, controlling tongue height for an open vowel (Gay, 1974).   Video clips of clients’ jaw mobility during conversational speech, before and after bite block invention, will be shown throughout this presentation.

These same clients were often able to produce the targeted speech sound(s) on the word level in a standardized articulation test but could not produce these same phonemes consistently on the conversational level.  The sentence, “As the rate and complexity of the statement increases, the intelligibility decreases,” is  found in many SLP’s reports to describe this breakdown in speech clarity.

More than forty years ago Edward Mysak suggested that if articulatory efforts are disrupted by excessive orofacial activities, as observed in many children with cerebral palsy, therapeutic techniques designed to restrain these compounding events must be administered to facilitate speech improvement (Mysak 1968).  Ten years later James Dworkin proposed a causal relationship between the articulatory imprecision exhibited by certain school-age children and their co-occuring interruptive, hyperactive or hypoactive mandibular movement patterns” (Dworkin 1978).  Clinical focus was then shifted to a treatment method that could measure the degree of jaw activity.  Acrylic bite blocks of varying heights were positioned between the upper and lower central incisor teeth. The children were required to bite down gently on a given block, so as to stabilize the mandible.  Substantial improvements in speech proficiency and intelligibility were obtained in all of the children studied in a relatively short period of time (Dworkin 1978). Kent and Lybolt (1982), Rosenbek and LaPointe (1985), Netsell (1985), and Dworkin (1991) all discussed the potential diagnostic and therapeutic value of bite block use in the differential diagnosis and treatment of dysarthric patients.

Other studies support the idea that SLPs need to take a closer look at how jaw grading is related to speech production.  A 2000 study reported, “precise control of jaw movements precedes lip-control, control over jaw and lip coupling, and independence of upper- and lower-lip movement” and “the present results might be taken to suggest that limited mandibular control in early speech is a negative prognostic factor for later speech motor delays” (Green, 2000).  Research into myofunctional disorders identified the relationship between the tongue and jaw dissociation for speech (Meyer, 2000).

In 2003, the following comments were made in a response to the Green, Moore, and Reilly article (Green, 2002) in reference “to the select populations of children and adults with developmental or neurogenic articulation disorders who exhibit mandibular dyscontrol. On the basis of our present work with such patients and a reinforcing clinical literature database, we suggest that the mandible may play a leading role not only in normal articulatory development but also in the origin and persistence of certain abnormal speech behaviors (Dworkin, 2003).

In our present study the charts of several different clinical populations were examined.  Subjects were chosen based upon the examiner’s comment that limited or excessive mandibular activity was observed during conversational speech.  A video-based movement tracking system had been used to chart the jaw range of motion in connected speech for each of the subjects. In the initial evaluation both the Goldman-Fristoe Test of Articulation (G-FTA-2) and the DCOMT (Dworkin-Culatta Oral Mechanism Examination and Treatment System) had been administered.  Based on the results of these inventories, all subjects had been diagnosed with a multiple articulation disorder and dysarthria. Client’s with the diagnosis of motor speech disorders such as Childhood Apraxia of Speech (CAS) or Acquired Apraxia of Speech (AOS) were not included in this study.

Bite blocks representing the following jaw heights were used to assess skills at the high jaw placement (m, b, p, f, v, n, s, z, ∫, t∫, r, vocalic r, I, I, Ʋ, u – teeth almost touching), medium jaw placement (θ, ð, l, t, d,Λ, ɛ, ə, ɔ - teeth slightly more open) and low jaw placement (g, k, h,ɑ, æ - teeth even slightly more open) (Marshalla, 1982).

Prior to data collection, these same bite blocks were used to assess the jaw skills of twenty-five randomly selected children and adults between the ages of 2.5 and 50 years whose speech clarity was considered to be within normal limits as reported by an independent judge. The task was to use the back molars to bite-and-hold the jaw still for fifteen (15) seconds, at each bite block height, while an isometric pull was introduced.  Each of these twenty-five individuals was able to perform the bite block task without error.  The SRJ Therapies client charts, spanning a period of 12 years, were then examined.  The following clients qualified for the study: 1) Down syndrome: 230, 2) Cerebral Palsy: 24, 3) Benign Hypotonia: 180, 4) Other syndromes characterized by hypotonia: 33, and 5) Clients with no medical diagnosis who had been enrolled in speech therapy for a minimum of four years  and who had not demonstrated significant improvement: 42.  The clients ranged in age from 2.5 years to 47 years.

The results of this retrospective study are remarkable in that only 8% of the 509  client-subjects were able to perform the bite block task without error; 92%  could not complete the task. These results suggest that jaw skills are related to deficits in speech clarity in clients with the diagnosis of a muscle-based multiple articulation disorder and dysarthria.  Because this was a retrospective study the limitations are clear. The next step would be large sample, double-blind studies that would definitively address the use of bite blocks for diagnosis and treatment of clients with muscle-based speech clarity disorders.  

Learner Outcomes: 

  1. Participants will be able to identify client’s with atypical jaw mobility during conversational speech.
  1. Participants will understand the possible relationship between atypical jaw mobility and dysarthria
  1. Participants will be able to use bite blocks to assess jaw skills in clients with the diagnosis of dysarthria


Dworkin, J. P. (1978). A therapeutic technique for the improvement of lingua-alveolar valving abilities. Journal of Language, Speech, and Hearing Services in Schools, 9, 162-175.

Dworkin, J. P. (1991). Motor speech disorders: A treatment guide- book. St. Louis: Mosby.

Dworkin, J. P. (1996). Bite block therapy for oromandibular dystonia. Journal of Medical Speech-Language Pathology, 4, 47-56.

Dworkin, J.P, Meleca, R.J., Stachler R.J. (2003) More on the Role of the Mandible in Speech Production: Clinical Correlates for Green, Moore, and Reilly’s (2002) Findings. Journal of Speech, Language, and Hearing Research, 46 (pp. 1020-1021).

Gay, T. J., Ushijima, T., Hirose, H., & Cooper, F. S. (1974). Effect of speaking rate on labial consonant-vowel articulation. Journal of Phonetics, 2, 47-63.

Green, J. R., Moore, C. A., Higashikawa, M., & Steeve, R. W. (2000). The physiologic development of speech motor control: Lip and jaw coordination. Journal of Speech, Language, and Hearing Research, 43, 239-255.

Green, J. R., Moore, C. A., & Reilly, K. J. (2002). The sequential development of jaw and lip control for speech. Journal of Speech, Language, and Hearing Research, 45, 66-79.

Kent, R., & Lybolt, J. (1982). Techniques of therapy based on motor learning theory. In W. H. Perkins (Ed.), Current therapy of communication disorders: General principles of therapy (pp. 13-25). New York: Thieme-Stratton.

Marshalla, (Rosenwinkel), P. (1982) Tactile-proprioceltive stimulation techniques in articulation therapy. Seminar handbook. Champaign: Innovative concepts in Speech and Language.

Meyer, P.G. (2000). Tongue lip and jaw differentiation and its relationship to orofacial myofunctional treatment. Int J Orofacial Myology, 26, 44-52

Mysak, E. D. (1968). Neuroevolutional approach to cerebral palsy and speech. New York: Teachers College Press.

Netsell, R. (1985). Construction and use of a bite-block for the evaluation and treatment of speech disorders. Journal of Speech and Hearing Disorders, 50, 103-106.

Rosenbek, J. C., & LaPointe, L. L. (1985). The dysarthrias: Description, diagnosis, and treatment. In D. F. Johns (Ed.), Clinical management of neurogenic communicative disorders (pp. 97-152). Boston: College Hill Press.

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