Acoustic and Psychophysical Dimensions of the Perceived Speech Naturalness of Nonstutterers and Posttreatment Stutterers

Abstract

The purpose of this study was twofold: to determine through psychophysical comparison of scaling data whether speech naturalness is a prothetic or a metathetic continuum, and to examine the relationship between selected acoustic characteristics of the speech of nonstutterers and treated stutterers and listeners' judgments of their speech naturalness. Comparison of magnitude estimation and interval scaling data indicated that speech naturalness behaves like a metathetic continuum, suggesting that either scaling procedure is valid for the quantification of this dimension. The speech of the nonstutterers was judged more natural than the speech of the treated stutterers, and a global voice onset time (VOT) measure (averaged across places of articulation) and a sentence duration measure were found to be the acoustic parameters most highly correlated with and predictive of speech naturalness. These results suggest the possibility that stuttering treatments that employ strategies like gentle voicing onset and prolonged speech may result in somewhat slower posttherapy speech patterns characterized by prolonged VOTs that could influence listeners to judge the speech as more unnatural than the speech of nonstutterers.

Darley's contributions to the understanding, differential diagnosis, and scientific study of the dysarthrias

“…Although directmagnitude estimation is the preferred method for this situation, the literature is based largely on data derived from the use of equal-appearing interval scaling. The issue of scaling method has been examined in a series of papers by Schiavetti and colleagues (Metz, Schiavetti, & Sacco, 1990;Samar & Metz, 1988;Schiavetti, 1984Schiavetti, , 1992Schiavetti, Metz, & Sitler, 1981).…”

Scaling of Voice Pleasantness and Acceptability in Tracheoesophageal Speakers

“…13 These results indicate that only ratio scales (eg, DME, visual analog) can be used to validly scale the specified dimensions of the population of speakers under study. However, other investigators have found that speech naturalness in posttreatment stutterers 14 and breathiness in normal speakers 15 behave like a metathetic continuum, indicating that EAI scales are valid methods of measuring these attributes of speech and voice.…”

Self-reported efficacy of an ear-level prosthetic device that delivers altered auditory feedback for the management of stuttering

“…The effectiveness of traditional behavioral therapies used to treat stuttering has been tarnished by a highly unnatural speech end-product (Metz et al, 1990;Franken et al, 1992;Kalinowski et al, 1994), difficulty in generalization outside of clinical settings and a high propensity for relapse (Craig and Calver, 1991;Boberg and Kully, 1994;Craig and Hancock, 1995;Dayalu and Kalinowski, 2002). In addition, efficiency is compromised when enormous amounts of time (Webster, 1980;Boberg and Kully, 1985) and effort are used to indirectly inhibit stuttering by learning and implementing novel speech patterns .…”