How fluent is the fluent speech of people who stutter? A new approach to measuring kinematics with ultrasound

ABSTRACT

We present a new approach to the investigation of dynamic ultrasound tongue imaging (UTI) data, applied here to analyse the subtle aspects of the fluency of people who stutter (PWS). Fluent productions of CV syllables (C = /k/; V = /ɑ, i, ə/) from three PWS and three control speakers (PNS) were analysed for duration and peak velocity relative to articulatory movement towards (onset) and away from (offset) the consonantal closure. The objective was to apply a replicable methodology for kinematic investigation to speech of PWS in order to test Wingate’s Fault-Line hypothesis. As was hypothesised, results show comparable onset behaviours for both groups. Regarding offsets, groups differ in peak velocity. Results suggest that PWS do not struggle initiating consonantal closure (onset). In transition from consonantal closure into the vowel, however, groups appear to employ different strategies expressed in increased variation (PNS) versus decreased mean peak velocity (PWS).

KEYWORDS:

• Dynamic analysis
• fluency
• gestural timing
• stuttering
• ultrasound

Acknowledgments

We thank all participants who gave up their time to complete the experiment. Special thanks go to Alan Wrench, Patrycja Strycharczuk, Steve Cowen, Ian Finlayson and Jana Walzog for their constant support. We gratefully acknowledge the support of Queen Margaret University, particularly the Clinical Audiology, Speech and Language Research Centre.

Declaration of interest

The authors report no conflicts of interest.

Notes

1. The script settings were the following: minimum pitch 60 Hz, time steps: 0 s, silence threshold: –25 dB, minimum silent interval duration: 0.3 s, minimum sounding interval duration: 0.1 s.

2. Including the interaction between prompt type and speaker group did not improve model fit.

3. Again, including the interaction between prompt type and speaker group did not improve model fit.