Effectiveness of frequency shifted feedback at reducing disfluency for linguistically easy, and difficult, sections of speech (original audio recordings included).

Frequency shifted feedback (FSF) induces fluency when presented to speakers who stutter. This study examined whether FSF was more effective at removing disfluencies on easy or on difficult stretches of speech (where difficulty was defined with respect to utterance and word length). There were more disfluencies on the difficult stretches than on the easy stretches. There were significantly fewer disfluencies under FSF than in normal listening conditions (indicating that FSF improved fluency). There was no interaction between difficulty of material and type of feedback when disfluency rate was used as the dependent variable, suggesting that targeting FSF on easy stretches of speech is as effective as targeting it on difficult stretches. The original audio data are provided in this report and can be used by readers to check for themselves the characteristics of voice control that alter when FSF is delivered.