Effects of speaking rate, loudness, and clarity modifications on kinematic endpoint variability

ABSTRACT

It is virtually impossible for a speaker to produce identical articulatory movements across several repetitions of the same utterance. This study examined how kinematic endpoint variability, defined as the positional variability of an articulator at its positional extremum, changes in response to cued speech behavioral modifications. As a second step, this study examined the strength of association between articulator speed and kinematic endpoint variability. Seventeen speakers repeated the sentence “Buy Kaia a kite” 10 times under the following conditions: typical, loud, slow, and clear speech. Speech movements were recorded using 3D electromagnetic articulography. Endpoint variability was measured at the maximum jaw opening position during “buy” and at the maximum elevation of the tongue back during /k/ in “Kaia”.

Significant speech modification effects were found for the jaw but not for the tongue. Specifically, typical speech yielded significantly lower kinematic endpoint variability than slow and loud speech. Further, jaw peak speed was moderately correlated with kinematic endpoint variability (r = .43, p < .01). Findings for jaw movements suggest that speech modifications that elicit an increase in speed (i.e. loud speech) may negatively impact kinematic endpoint precision; however, other factors such as motor learning and lacking emphasis on spatial precision (i.e. slow speech) may also play a role.

KEYWORDS:

• Articulation
• kinematics
• electromagnetic articulography

Acknowledgments

This research was supported by start-up funds from Vanderbilt University Medical Center and grant R03DC015075 from the National Institute on Deafness and Other Communication Disorders (NIDCD). The content of this manuscript is solely the responsibility of the author and do not necessarily represent official views of the NIDCD. The author would like to thank Brett Myers for his help with data collection and Ellen Hart, Sophie Mouros, Jaclyn Fitzsimmons, and Mary Jo Bissmeyer for their help with data analysis.

Disclosure statement

The author reports no conflicts of interest.

Additional information

Funding

This research was supported by start-up funds from Vanderbilt University Medical Center and grant R03DC015075 from the National Institute on Deafness and Other Communication Disorders (NIDCD).