The Perception of Speech Naturalness of Post-Therapeutic and Altered Auditory Feedback Speech of Adults with Mild and Severe Stuttering

Abstract

The effect of therapy and altered auditory feedback (AAF) on the perception of speech naturalness of people who stutter was examined. Thirty-five naïve young adult listeners rated speech samples from fluent speakers and individuals who stutter. Samples came from normal adults who spoke Standard American English; adults with mild or severe stuttering who spoke under conditions of non-altered feedback (NAF), delayed auditory feedback (DAF), and frequency-altered feedback (FAF); and adults with mild or severe stuttering prior to and following successful completion of a Precision Fluency Shaping Program. Speech produced under AAF was rated as significantly more natural sounding than speech from the same individuals under NAF (p < 0.0001). Speech produced during FAF was judged to be more natural sounding than that produced during DAF for those with mild (p = 0.003) and severe (p < 0.0001) stuttering. Mild stuttered speech was judged to have more natural-sounding speech than severe stuttered speech during AAF (p < 0.0001). Speech from individuals following therapy was rated significatly less natural sounding than that from individuals during AAF for both mild and severe stuttering (p < 0.0001). The speech of individuals prior to therapy was rated significantly more natural than their speech produced after therapy (p < 0.0001). Speech from normal fluent speakers was rated as significantly more natural sounding than all samples produced from the individuals who stutter (p < 0.0001). These findings support the contention that AAF benefits those who stutter through a reduction of stuttering with a gain in perceived speech naturalness.

Investigations of the impact of altered auditory feedback in-the-ear devices on the speech of people who stutter: One-year follow-up

“…13 The extraction, editing, and compact disk recording of files is described in details elsewhere. 2,13 A total of 75 speech samples were recorded onto a compact disk (CD) in a randomized order for rating.…”

The role of auditory temporal cues in the fluency of stuttering adults

“…According the literature, the most cited effect of delayed auditory feedback in fluent persons is the reduction of speech rate [23][24][25] . It should be noted that the findings of this study confirm this statement, since in both spontaneous speech and reading there was a decrease in the flow of syllables and words per minute in fluent adults.…”

“…Studies in fluent individuals have shown that delayed auditory feedback (DAF) has caused difficulties in speech fluency [16][17][18][19][20][21][22] , and decrease in speech rate [23][24][25] .…”

Realimentação auditiva atrasada e tratamento de gagueira: evidências a serem consideradas

“…While Martin et al (1984) found no difference in naturalness in people who stutter under non-altered feedback compared to DAF, Stuart and Kalinowski (2004) and Stuart et al (2006) found speech significantly more natural sounding with the device than without the device. Perhaps this divergent findings result from the use of a different delay time (250ms in the study of Martin et al1984 versus 50ms and 60ms in the study of Kalinowski, 2004 andStuart et al 2006 respectively) and maybe also the combination with frequency altered feedback (+ 500Hz in the study of Stuart et al 2006). Natke (2000) suggested that the critical delay time with respect to naturalness lies at 100 ms, above which speech would start to sound unnatural.…”

“…Soon after studies appeared showing that in individuals who stutter, by contrast, DAF may improve speech fluency (Nessel, 1958;Lotzmann, 1961;Chase et al, 1961a;Bohr, 1963;Zerneri, 1966;Soderberg, 1969). Today there is some evidence that the use of DAF is a potentially helpful technique in the treatment of stuttering (Kalinowski et al, 1993(Kalinowski et al, , 1996Stuart et al, 1997;Stuart and Kalinowski , 2004;Macleod et al, 1995;Van Borsel et al, 2003). Several devices for DAF are also commercially available ranging from large-sized desk models over body-worn battery-powered devices to (almost) invisible prosthetic DAF devices.…”