Yorkston & Beukelman (1981)




Single Subject Designs


SOURCE:  Yorkston, K., & Beukelman, D. R.  (1981).  Ataxic dysarthria:  Treatment sequences based on intelligibility and prosodic considerations.  Journal of Speech and Hearing Disorders, 46, 398-404.


REVIEWER(S):   pmh


DATE: 7.09.12




TAKE AWAY: Promising insights regarding improving rate and intelligibility among speakers with ataxic dysarthria.



1.  What was the focus of the research?  Clinical Research



2.  What type of evidence was identified?                                         

a.  What type of single subject design was used?  Case Study:  Program Descriptions with Case Illustrations

b.  What was the level of support associated with the type of evidence?  Level = D+


3.  Was phase of treatment concealed?                                            

a.  from participants?  No

b.  from clinicians?  No

c.  from data analyzers?  No


4. Were the participants adequately described?   Yes

a.  How many participants were involved in the study?  4       

b.  The following characteristics/variables were described     

•  age:  23-55

•  therapy initiated post onset:  2-6 weeks

•  therapy ended post onset:  8-10 mo

•  etiology:  anoxic encephalopathy (2); closed head trauma (2)

•  coma:  <1-4 weeks

•  wheelchair use:  all initially; at end, none but 1 P required standby guarding

c.  Were the communication problems adequately described?  Yes,  sudden adult-onset ataxic dysarthria; no degenerative cerebellar disease

  intelligibility:  10-25%

•  rate:  110-132 wpm

•  other:  Language and cognitive skills not described



5.  Was membership in treatment maintained throughout the study?  Yes

a.  If there was more than one participant, did at least 80% of the participants remain in the study?  Yes                            

b.  Were any data removed from the study?  No



6.  Did the design include appropriate controls? No, this was a case study.

a.  Were baseline data collected on all behaviors?   No

b.  Did probes include untrained data?  No

c.  Did probes include trained data?  No

d.  Was the data collection continuous?  No

e.  Were different treatment counterbalanced or randomized?  Does not apply



7.  Were the outcomes measure appropriate and meaningful? Yes

a.  List the outcomes of interest (dependent variable):

OUTCOME #1:  Speaking rate—WPM (decrease)

OUTCOME #2:  Intelligibility rate (increase)

NOTE:  Both outcome measures were derived from reading tasks.

b.  List the outcome measures that are subjective:  #1-2

c.  List the outcome measures that are objective:  None

d.  Are the outcome measures reliable?          Data not provided



8.  Was there improvement in the outcome measures?

a.  Did the target behavior improve when it was treated?   Yes, for the most part but the evidence is descriptive only.  The rate of one P did not improve.

b.  Overall quality of improvement, if anyStrong, although the rate of one P did not improve.

For all other Ps, rate decreased and intelligibility increased.

9.  Description of baseline:

a.  Was there baseline data?  Not really; there was a single data of preintervention and post intervention data.

b.  Was baseline low or high (as appropriate) and stable?  NA

c.  What was the percentage of nonoverlapping data?  NA

d.  Does inspection of data suggest that the treatment was effective?  Yes



10.  What was the magnitude of the treatment effect?  Not provided



11.  Was information about treatment fidelity adequate?  Not provided


PURPOSE:  present treatment strategies used with 4 speakers with ataxic dysarthria

POPULATION:  ataxic dysarthria, adult sudden onset



MODALITY:  expressive






ELEMENTS OF PROSODY USED AS INTERVENTION (part of independent variable):  stress, duration, loudness, rate, pause,




DOSAGE:  not clear, no more than 9 ½ months in duration





STIMULI:  auditory, visual (oscoilloscope)




MAJOR COMPONENTS:  focused on oral reading; this summary only discusses prosody related activities

TECHNIQUES:  imitation, modeling, biofeedback, reading,


Skill therapy(Administered in order)

Step #1:  Rigid Imposition of Rate

•  This was the initial stage of intervention because Ps could not monitor/modify speaking rate.

•  C introduced alphabet board and pacing board.

•  Rate decreased but Ps seemed to lengthen pause time and did not increase the duration of speech sounds.

Step #2:  Rhythmic Cueing

•  Step #1 reduced rate but disrupted prosody..

•  This step was a transitional stage to prepare for self-monitoring

•  C signaled which words should be read by pointing to them;

–  stressed words cues were presented slowly ans

–  unstressed word cues were presented relatively quickly.

•  C gradually faded cues.

Step #3:  Oscilloscope Feedback

•  C facilitated intelligibility and naturalness by modifying any “problem” areas.

•  For example, C directed P to fill up the screen with vocalization while reading a sentence OR

•  C directed P to match modeled sentences on the oscilloscope.

Step #4.  Establishing Optimum Rate and Intelligibility Relationships/Trade-off

•  C identified trade-offs between rate and intelligibility.

•  P practiced reading sentences that maximized intelligibility and rate.


Normalizaton therapy


•  Following the stabilization of rate and intelligibility, C identified the aspects of prosody that were atypical.

•  This was accomplished using perceptual and acoustic measures.

•  C considered the P’s ability to modify prosodic features (pitch, loudness, duration, pause) and guided P to minimize atypical patterns.

•  The goal was to produce the most natural prosody possible.


Self-Monitoring therapy

Step #1:  C imposed appropriate rate.


Step #2:  P identified excessive rates during intervention sessions.


Step #3:  P generalized to contexts outside the therapy session.



•  Within session:

–  P predicted the intelligibility of an utterance (varied from single words, phrases, and paragraphs)

–  P compared target to C’s transcription of a sentence.

•  Homework

–   P read and recorded sentences composed from frames using the following  structure:  The (adjective) (subject) are (verbed) by the (agent). 

–  There were approximately 50 words which the P could select from within each frame.

–  P noted which words were selected and combined within each frame.

– The next day the P transcribed the recorded sentences and compared them to the targets from the day before.



OUTCOME #1.  Speaking rate (decrease)

OUTCOME #2.  Intelligibility rate (increase)






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