[Reduction of stuttering frequency using frequency-shifted and delayed auditory feedback]

In 12 stuttering subjects the fluency enhancing effect of delayed auditory feedback (DAF) and frequency-shifted auditory feedback (FAF) was compared. The subjects had to read three passages consisting of 300 syllables under simultaneous auditory feedback, DAF (delay time: 53 ms) and FAF (frequency shift: -(1/2) octave). Stuttering frequency and percentage of discontinuous speech time were determined. Only under DAF a fluency enhancing effect in the mean values was observed, but not under FAF. However, in 4 subjects a reduction in stuttering frequency of 50% occurred. The conclusion is drawn that the use of FAF as a prosthetic device is limited. The relationship between prolonged speech and fluency enhancing is discussed.