Adults who stutter and metronome synchronization: evidence for a nonspeech timing deficit

Abstract

Speech timing deficits have been proposed as a causal factor in the disorder of stuttering. The question of whether individuals who stutter have deficits in nonspeech timing is one that has been revisited often, with conflicting results. Here, we uncover subtle differences in a manual metronome synchronization task that included tempo changes with adults who stutter and fluent speakers. We used sensitive circular statistics to examine both asynchrony and consistency in motor production. While both groups displayed a classic negative mean asynchrony (tapping before the beat), individuals who stutter anticipated the beat even more than their fluent peers, and their consistency was particularly affected at slow tempi. Surprisingly, individuals who stutter did not have problems with interval correction at tempo changes. We also examined the influence of music experience on synchronization behavior in both groups. While music perception and training were related to synchronization behavior in fluent participants, these correlations were not present for the stuttering group; however, one measure of stuttering severity (self‐rated severity) was negatively correlated with music training. Overall, we found subtle differences in paced auditory−motor synchronization in individuals who stutter, consistent with a timing problem extending to nonspeech.

Neural Correlates of Vocal Pitch Compensation in Individuals Who Stutter

“…We recently showed that individuals who stutter are more variable in responding to manipulations of pitch feedback while speaking, both in the number of compensatory responses and in the timing of those responses, and that this variability correlates with self-rated stuttering severity (Sares et al, 2018). The results of this and other behavioral studies (Kalinowski et al, 1993;Cai et al, 2014) point to a timing problem during auditory-motor behavior, something that also appears to extend to non-speech (Cooper and Allen, 1977;Ward, 1997;Boutsen et al, 2000;Subramanian and Yairi, 2006;Falk et al, 2015;van de Vorst and Gracco, 2017;Sares et al, 2019). Neuroimaging studies have identified differences in motor and auditory regions of the brain in adults who stutter (AWS; Foundas et al, 2001;Brown et al, 2005;Nil et al, 2008;Chang et al, 2009;Kell et al, 2009;Beal et al, 2010Beal et al, , 2011Kikuchi et al, 2011;Budde et al, 2014;Belyk et al, 2015).…”

Rhythmic tapping difficulties in adults who stutter: a deficit in Central Clock and/or Motor Implementation?

“…Furthermore, some rhythmic conditions, such as singing or speaking along with a metronome, frequently improve the speech fluency of people who stutter (21)(22)(23)(24). Altogether, these observations suggest that stuttering is related to a temporal processing deficit (25)(26)(27)9,10,28).…”

“…-Phase Locking Value (PLV), characterizing the consistency of the beat-tap synchrony, defined as the norm of the sum of all the 𝑃𝐴 44444⃑ vectors (𝑃𝐴 44444⃑ is a unit vector of phase PA in a plane) divided by their number (Lachaux et al, 1999; Sares et al, 2019). In case the beattap asynchrony, and therefore the PA values, remain constant over a complete tapping train, the corresponding 𝑃𝐴 44444⃑ vectors align and their sum results in a vector of maximum length (i.e., ideally a PLV of 1).…”

“…People who stutter (PWS) frequently produce perceptually disfluent speech, containing repeated, extended and blocked sounds, and disrupted rhythmic flow (2). Although the etiology of stuttering appears to be multifactorial and is not well understood yet, the current literature converges on the idea that stuttering is a neuro-motor disorder (3,4) modulated by psychological factors (5), which is not speech-specific, and affects general motor control as well (6)(7)(8)(9)(10).…”

“…Several studies have explored this temporal processing deficit hypothesis by means of finger tapping tasks, and observed that both during paced tapping, synchronized with an external metronome or musical excerpt (9,27), and during continued un-paced tapping (28), PWS are more variable than people who do not stutter (PNS). In addition, when tapping along with a simple rhythm or with rhythmically more complex musical excerpts, PWS show a greater Negative Mean Asynchrony (NMA) compared to PNS (9,27), i.e. they anticipate the metronome beat to a greater extent.…”