The Impact of Social–Cognitive Stress on Speech Variability, Determinism, and Stability in Adults Who Do and Do Not Stutter

Abstract

,f,g Purpose: This study examined the impact of social-cognitive stress on sentence-level speech variability, determinism, and stability in adults who stutter (AWS) and adults who do not stutter (AWNS). We demonstrated that complementing the spatiotemporal index (STI) with recurrence quantification analysis (RQA) provides a novel approach to both assessing and interpreting speech variability in stuttering. Method: Twenty AWS and 21 AWNS repeated sentences in audience and nonaudience conditions while their lip movements were tracked. Across-sentence variability was assessed via the STI; within-sentence determinism and stability were assessed via RQA. Results: Compared with the AWNS, the AWS produced speech that was more variable across sentences and more deterministic and stable within sentences. Audience presence contributed to greater within-sentence determinism and stability in the AWS. A subset of AWS who were more susceptible to experiencing anxiety exhibited reduced across-sentence variability in the audience condition compared with the nonaudience condition.Conclusions: This study extends the assessment of speech variability in AWS and AWNS into the social-cognitive domain and demonstrates that the characterization of speech within sentences using RQA is complementary to the across-sentence STI measure. AWS seem to adopt a more restrictive, less flexible speaking approach in response to social-cognitive stress, which is presumably a strategy for maintaining observably fluent speech.

The Effects of Emotion on Second Formant Frequency Fluctuations in Adults Who Stutter

“…On the contrary, a more recent study by Jackson et al [68] showed an increase in stability between articulatory gestures when speaking in front of an audience, a change only observed in the stuttering group. The authors proposed that an increase in intergestural stability found in the AWS was due to a less flexible system that is “overly stable,” rendering it more prone to breakdown as they have a decreased ability to respond to extraneous factors.…”

“…Using kinematic analysis, Jackson et al [68] found increased intergestural stability in lip movement in AWS compared to the ANS when speaking in front of an audience. Similarly, smaller interlip phase differences in AWS compared to controls were reported by van Lieshout et al [66] when speaking under cognitively stressful conditions.…”

Recurrence Quantification Analysis of Sentence-Level Speech Kinematics

“…Defending their STI approach, Smith, Johnson, McGillem, and Goffman (2000) argued that for their purpose of measuring the effects of contextual variables on speech, linear normalization procedures were sufficient because their questions did not require the identification of speech landmarks (though, they did in fact specify start and end points at peak velocity points). Still, Jackson, Tiede, Beal, and Whalen (2016) found significant correlations between STI and sentence duration-sentences with longer duration were associated with higher STI values, and those with shorter duration were associated with lower STI. Taken together, results from Lucero (2005), Ward and Arnfield (2001), and Jackson et al (2016) suggest that utterance duration may significantly influence STI values.…”

“…Still, Jackson, Tiede, Beal, and Whalen (2016) found significant correlations between STI and sentence duration-sentences with longer duration were associated with higher STI values, and those with shorter duration were associated with lower STI. Taken together, results from Lucero (2005), Ward and Arnfield (2001), and Jackson et al (2016) suggest that utterance duration may significantly influence STI values.…”

“…The data set presented constitutes the control group from the first author's dissertation project, which examined variability in adult speakers who do and do not stutter. Those results are presented in full in Jackson et al (2016).…”