The Immediate and Long-term Effects of Altered Auditory Feedback (AAF) on the Characteristics of Persistent Developmental Stuttering
Altered auditory feedback (AAF) has been available in the form of portable speech aids for approximately one decade. This progression in technology enables people who stutter (PWS) to take advantage of the supposed fluency-enhancements caused by modifications in audition in every-day life. While clinical studies have shown that some PWS experience significant reductions in stuttering when utilizing AAF, it remains difficult to predict whether or not an interested individual may benefit from a speech aid. Questions that remain unanswered particularly relate to the extent and longevity of the fluency-enhancement possible through AAF device usage.
The purpose of the two clinical trials, presented herein, lay within the more specific exploration of the effects of portable AAF devices. One the one hand, the immediate effects study aims at in vestigating the degree and kind of improvement caused by the speech aids on features of stuttering severity. On the other hand, the longterm study is exploring the longevity of improvements in speech fluency as well as user satisfaction in speaking situations of daily life.
The immediate effects study included 30 PWS in the agerange of 18-68 years (M = 36.5; SD = 15.2), who used two different portable AAF devices during various speech tasks in a clinical setting. The participants were exposed to different experimental conditions (no device, placebo, active AAF using device A, and active AAF using
device B) while producing speech samples. The recordings were then electronically analyzed to detect changes in select features of stuttering;
frequency, duration, speech rate, articulation rate and core behaviors. Throughout the subsequent longitudinal study 6 of the 30 participants were provided with a portable AAF unit in order to use the device as desired in situations of daily life. The continued effects on features of stuttering severity as well as the subjective impressions
of the extended device usage were evaluated.
Data analysis shows a statistically significant reduction in stuttering frequency when using both devices within all speech samples (p = .000). Throughout the placebo condition those clients with advanced stuttering severity ratings experienced a statistically significant improvement in speech fluency (p = .024). The prolonged use of a technical speech aid in the context of every-day life resulted in statistically significant reductions in the percentage of stuttered syllables, both at the beginning and end of the three-month trial period. The subjective impressions of the participant group were extremely heterogeneous.
Results generally show that a portable AAF device has the potential of reducing stuttering frequency upon first use as well as in the long run. However, the individual perception of the magnitude of such reductions varied widely. Whether or not a PWS perceives the use of a device beneficial must be decided individually, ideally based on a thorough trial use of the speech aid in various speaking situations and contexts.