For each participant, samples of spontaneous speech were collected through audiovisual recording in two different listening conditions: with non-altered and delayed auditory feedback. The sequence of tasks recordings was the same for all participants.
Then, it was carried out the collection of spontaneous speech sample in the listening condition with delayed auditory feedback. The discussed topic was different from the speech collection in the non-altered listening condition, to avoid the effect of adaptation.
There was no reduction of most disfluencies under the effect of delayed auditory feedback. The word repetition was the only type of disfluency that showed significant reduction under the effect of delay.
Table 5 presents the descriptive statistics for the speech rate - syllables per minute and words per minute - and percentage of stuttering-like disfluencies in listening conditions with non-altered and delayed auditory feedback. There was a reduction in the flow of syllables per minute under the effect of delay.
The delayed auditory feedback in the persons who stutter caused as immediate effect a significant reduction in the frequency of word repetitions.
The effect of delayed auditory feedback on disfluencies of duration (block, prolongation and pause) and repetition (word, part of word and sound repetition) showed a statistically significant decrease only in repetition disfluencies.
There was an increase in the common disfluencies occurrence and speech discontinuity in spontaneous speech with delayed auditory feedback, and a decrease in the flow of syllables and words per minute (Table 2).
There was an increase in the occurrence of stuttering-like disfluencies and speech discontinuity, as well as a decrease in the amount of common disfluencies in the delayed auditory feedback condition.
Researches (37) also suggest that the act of monitoring another speech, as with the chorus effect that delayed auditory feedback causes, assists the stuttering speaker to generate temporal patterns and articulatory gestures that are necessary in fluent speech.
There was a mean reduction in the frequency of stuttering-like disfluencies of 27.5% with delayed auditory feedback, lower than those reported in other studies that were performed using SpeechEasy 45% (29) and 40% (30).
The results regarding the effects of delayed auditory feedback on spontaneous speech and reading of fluent adults showed that there was a significant effect for all measures assessed on the frequency of disfluencies and the speech rate, except for stuttering-like disfluencies in spontaneous speech.