Thomas David Kehoe

Dozens of studies have investigated the immediate effects of anti-stuttering devices, typically finding 60-80% reductions in stuttering. However, only a handful of long-term studies have been published.

Two studies investigated Casa Futura Technologies' School DAF anti-stuttering device. In the first study, nine adults used the devices thirty minutes a day for three months. They didn't receive speech therapy. No statistically significant "wearing off" of effectiveness was seen when wearing the devices after three months. When the subjects weren't wearing the devices, at the end of the study, they stuttered on average 55% less ("carryover fluency") than at the start of the study. In other words, the subjects needed the devices "less and less as time passes" due to improved physical speech. (Van Borsel, 2003) A second study found similar results after one year, combining the device with speech therapy. (Radford, 2005)

One long-term study investigated the SpeechEasy DAF/FAF anti-stuttering device. Nine subjects used the devices about seven hours per day, for twelve months. At the end of the study there was no statistically significant change in fluency when wearing the device (i.e., no "wearing off" of effectiveness) or when not wearing the device (i.e., no "carryover fluency"). This study suggests that SpeechEasy users don't experience needing their devices "less and less as time passes." (Stuart, 2004)

An unpublished study of SpeechEasy anti-stuttering devices tested six subjects after on average eighteen months use of the device. Two subjects were stuttering about as much as before they purchased the device. The other four subjects were worse. On average, the subjects' stuttering had increased about 50%. (Runyan, 2005)

Why do some devices improve users' speech over time, leading to the users needing the devices "less and less as time passes," but other devices don't, or possibly make users' speech worse? Are the effects due to physical changes in users' speech, or due to psychological changes? How could anti-stuttering devices be improved, or how should consumers use the devices, to maximize positive long-term effects?

Casa Futura Technologies has developed several innovations to improve long-term effectiveness. First, octave-scale FAF downshifting is used, which studies of non-stutterers found induced changes in vocal pitch, due to changes in speech motor (muscle) activity such as relaxed breathing and relaxed vocal folds. (Elman, 1981)

Second, Casa Futura Technologies Pocket Speech Lab monitors the user's vocal fold tension. When the user speaks with tense vocal folds, the device switches on DAF and FAF to induce speech motor changes. When the user speaks with relaxed vocal folds, the device switches off the sound. The user is thus trained to speak with relaxed vocal folds, without relying on DAF and FAF.

Third, improved training materials (including a video) encourage consumers to use the devices to help them slow their speaking rate by stretching vowels (continuous phonation), to speak with relaxed breathing and vocal folds, and to make psychological changes such as talking more or identifying and reducing speech-related fears and anxieties.