Speech-Language Pathology/Stuttering/Fluency-Shaping Efficacy Studies
This chapter focuses on long-term studies of fluency shaping stuttering therapies, published in peer-reviewed journals.
Satisfaction with "Smooth Speech" Fluency Shaping
In a study of a "smooth speech" fluency shaping stuttering therapy program, about 95% of stutterers were "very satisfied" or "satisfied" with their speech at the end of the treatment. A year later, their satisfaction dropped to 43%.
ISTAR Comprehensive Stuttering Program
The fluency shaping program was based on slow, prolonged speech, starting with 1.5 seconds per syllable stretch, and ending with slow-normal speech. The program also works on reducing fears and avoidances, discussing stuttering openly, and changing social habits to increase speaking. The program includes a maintenance program for practicing at home. The therapy program reduced stuttering from about 15-20% stuttered syllables to 1-2% stuttered syllables.
12 to 24 months after therapy, about 70% of the stutterers had satisfactory fluency. About 5% were marginally successful. About 25% had unsatisfactory fluency.
Attrition in a Long-Term Study
A study of a "prolonged speech" fluency shaping stuttering therapy program had 32 stutterers initially speak about five times slower than normal speech, then gradually increase their speaking rate. Six subjects (19%) failed to learn the "prolonged speech" technique during the two-week residential therapy program. Eight subjects (25%) completed the residential training but refused to participate in a six-week, weekly therapy "phase II" program. Six subjects (19%) completed the six-week "phase II" program but refused to participate in the year-long "maintenance" program with infrequent therapy at the speech clinic.
One year later, the twelve subjects (38%) who stayed in the program were able to speak nearly fluently. Was this therapy program a success? 100% of the stutterers who completed the program were successful. But two-thirds of the stutterers didn't complete the program.
SLPs vs. Parents vs. Computers
A study of 98 children, 9 to 14 years old, compared three types of stuttering therapy. The three types of therapy were:
- Intensive "smooth speech" fluency shaping trained relaxed, diaphragmatic breathing; a slow speaking rate with prolonged vowels; gentle onsets and offsets (loudness contour); soft articulation contacts; and pauses between phrases. The children did this therapy in a speech clinic for 35 hours over one week.
- Home-based "smooth speech." This was similar to the first group, but parents were included, and encouraged to continue therapy at home. Therapy was done in a speech clinic for six hours once a week for four weeks (24 hours total).
- Electromyographic biofeedback. The children used an EMG biofeedback computer system about six hours a day for one week (30 hours total). The EMG system monitored the child's speech-production muscle activity. The children were instructed to tense and then relax their speech-production muscles. The goal was to develop awareness and control of these muscles. The children then worked through a hierarchy from simple words to conversations, while keeping their speech-production muscles relaxed. After mastering this while watching the computer display, the children did the exercises with the computer monitoring but not displaying their muscle activity. The speech pathologists did relatively little with the children: "Constant clinician presence was not necessary as the computer provided feedback as to whether the child was performing the skills correctly."
A fourth (control) group didn't receive any stuttering therapy.
At the end of each therapy program, all three therapies reduced stuttering below 1% on average. The control group had no improvement in fluency.
One year after the therapy program, the percentage of children with disfluency rates under 2% were:
- 48% of the children from the clinician-based program.
- 63% of the children from the parent-based program.
- 71% of the children from the computer-based program.
The results for children with disfluency rates under 1% were even more striking:
- 10% of the children from the clinician-based program.
- 37% of the children from the "parent-based" program.
- 44% of the children from the computer-based program.
I.e., the computers were most effective, the parents next most effective, and the speech-language pathologists were least effective in the long term. At the 1% disfluency level, the computers and the parents were about four times more effective than the speech-language pathologists.
Four years later, all three groups had average stuttering reductions between 76% and 79%. This may have been due to the more dysfluent children receiving additional speech therapy.
Computer System for Reducing Short Phonation Intervals
Another study had five stutterers use a computer that trained reduction of short phonation intervals. Normal speakers switch their vocal folds on and off many times each second, as they pronounce vowels and voiced consonants, such as /b/ and /g/, and then unvoiced consonants such as /s/ and /t/. A core stuttering behavior is an inability to quickly switch from voiceless to voiced sounds, i.e., to instantly switch on your vocal folds. The computer program trained stutterers to slow down that part of speech without slowing down other parts of speech (and so maintain natural-sounding speech). One year post-therapy all five subjects were able to speak nearly fluently. Larger clinical trials are scheduled for 2006.
- ^ Craig, A., Calver, P. "Following Up on Treated Stutterers: Studies of Perceptions of Fluency and Job Status." Journal of Speech and Hearing Research, 34, 279-284, April 1991.
- ^ Boberg, E., & Kully, D. (1994). "Long-term results of an intensive treatment program for adults and adolescents who stutter." Journal of Speech and Hearing Research, 37, 1050-1059.
- ^ Onslow, M., et al., "Speech Outcomes of a Prolonged-Speech Treatment for Stuttering," Journal of Speech and Hearing Research, 39, 734-749, 1996.
- ^ Craig, A., et al. "A Controlled Clinical Trial for Stuttering in Persons Aged 9 to 14 Years" Journal of Speech and Hearing Research, 39:4, 808-826, August 1996.
- ^ Hancock, et al. "Two- to Six-Year Controlled-Trial Stuttering Outcomes for Children and Adolescents," Journal of Speech and Hearing Research, 41:1242-1252, December 1998.
- ^ Ingham, et al., (2001), "Evaluation of a Stuttering Treatment Based on Reduction of Short Phonation Intervals," Journal of Speech, Language, and Hearing Research, 44, 1229-1244.