Section 7 - Using Facilitator Delayed Auditory Feedback
For the patient whose speech improves with delayed auditory feedback (DAF), the DAF on the Facilitator makes the instrument a powerful assistive speaking device.
Delayed auditory feedback (DAF) apparently degrades the individual’s ability to self-monitor his or her ongoing speech. In the normal speaker, the introduction of DAF via headphones breaks down the speaker’s fluency, often producing prolongation of vowels and slurring of articulation. Under conditions of DAF, most normal speakers will show a marked interruption of normal prosodic speaking patterns. Conversely, in the stutterer, speech may become more fluent under DAF, probably related to the prolongation of vowels which results in a general slowing down of speaking rate (1). Slowing down the stutterer’s rate of speech is often facilitative for improving overall speech fluency.
Voice clinicians occasionally use DAF with patients with functional dysphonia. Although the physical vocal mechanisms appear to be structurally and functionally within normal limits, the patient’s voice is faulty. Asking such a patient to read aloud wearing headphones under conditions of DAF will sometimes result in a marked improvement of vocal quality. It almost appears that when the patient is not able to monitor auditorily what he or she is saying (because of the delayed feedback), a more natural voice may emerge. The DAF-induced "better" voice is then recorded and used subsequently as the patient’s voice model in therapy. With voice patients, the DAF is used primarily diagnostically and is rarely used as a voice therapy technique in voice therapy.
Greene and Mathieson (2) report on using DAF as a continuing method for slowing down speech rate in Parkinson’s disease. The Parkinson patient wears a "portable, body-worn DAF device" as an assistive device. Under conditions of DAF, the resulting reduction of speech rate in the Parkinson patient appears to produce, also, louder, more intelligible speech. It should be pointed out that in the treatment of Parkinson’s disease, focusing on one speech component, such as increasing voice loudness (3) or increasing sharpness of articulation, will tend to generalize an improvement in most components of Parkinson speech (improves loudness, sharpens articulation, and slows speaking rate). The use of DAF in the treatment of dysarthrias (CVA-caused, multiple sclerosis, etc.) can be used diagnostically in therapy; if the DAF enhances speech performance, a portable DAF may be helpful in improving the patient’s speech.
Examples of Cases Using DAF
Max was a 16-year old boy who for most of his school years was classified as "learning disabled". It was not until he moved to the city and was in high school that he was first seen and tested by an SLP who felt that one of his primary problems was "cluttering". His speech patterns were extremely rapid (over 220 words per minute, he exhibited many articulation errors, and at times, he would repeat initial syllables when attempting to say a phrase). As part of his evaluation, his speech was assessed while he wore headphones attached to a DAF unit. Under DAF at approximately 250 ms, his speech rate dropped to below 180 words per minute, he spoke with greater loudness, his articulation improved, and his dysfluency disappeared. Attempts were made unsuccessfully at that time to find a portable DAF unit that Max could wear in the classroom and out of school. No such portable DAF units were available. Instead, Max would practice on his own in the speech room using the DAF on a Visi-Pitch three or four times weekly, working to slow down his speaking rate and to speak louder. The SLP did have a portable speech amplifier that Max took out of the clinic for self-practice. One can only speculate that had Max been able to use the DAF on the portable Facilitator out of the clinic that he would have had good early success improving his overall communication skills.
Louise, age 44, was an acquisitions editor for a major publisher. Following a severe influenza with complete laryngitis, her voice was very slow in coming back. Three months after onset, she was seen for a voice evaluation. Endoscopic testing found her to have "a normal larynx and airway"; acoustic analyses found her habitual speaking Fo to be near 260 Hz, her intensity levels at the time were barely audible, air flow rates were high with low pressure values. As part of a diagnostic probe, she was asked to wear headphones; with amplification, her voice loudness and voice quality improved. Unexpectedly, speaking against the delayed auditory feedback on the Visi-Pitch II, produced a lowering of Fo to near 210 Hz with a voice loudness level that was dramatically improved. Her voice under DAF conditions was recorded on a cassette and played back to her. Subsequently, we used DAF in therapy, and she was able to visualize her improved voice characteristics on the Visi-Pitch. A portable DAF instrument was then used at home during her home-practice sessions. She would record what she sounded like reading with DAF, and then listen to the playback on her recorder. She was then able to produce the same improved voice that she had heard on the recorder without any assistance. The patient has now had a normal voice with no symptoms for the past eight months.
Recommended Procedures for Using DAF
1. The selector mode on the Facilitator is set to DAF (the letters DAF appear on the instrument window). The loudness level of amplification-DAF is determined by the relative setting of the VOLUME switch.
2. The relative time-delay on the Facilitator ranges from .05 to 0.5 secs, with the clinician able to control the delay-time by increments of approximately 10 msecs (timing changes in msecs are achieved by adjusting the delay time to the value appearing in the instrument window).
3. Explain to the patient something like this, "I want you to wear these headphones as you read (or repeat) aloud. What you say will be fed back to you on the phones a bit delayed. You won’t be able to hear yourself as you usually do when you speak. Just keep speaking. I will record on another recorder how you sound."
4. After the initial testing on the effects of DAF on speech and voice, play the recorded output back to the patient. Depending on the effects of DAF, either go forward with more DAF practice or stop using it.
5. For those patients who profit from using DAF, it is recommended that the patient wear a portable Facilitator in the provided waist-pack. The DAF mode should be used whenever it appears to facilitate better speech or better oral reading.
(1) Shames, G.H. and Florence, C. (1980). Stutter-Free Speech: a Goal of Therapy. Columbus, OH: Charles E. Merrill.
(2) Greene, M.C.L. and Mathieson, L. (1989). The Voice and Its Disorders, 5th Ed. London: Whurr Publishers.
(3) Raming, L.O., Countryman, S., Thompson, L.L., and Horii, Y. (1995). Comparison of two forms of intensive speech treatment for Parkinson’s disease. Journal of Speech & Hearing Research, 38: 1232-1251.