Publication
Investigating articulatory differences between upright and supine posture using 3D EMA
Ingmar Steiner; Slim Ouni
In: Yves Laprie; Ingmar Steiner (Hrsg.). 9th International Seminar on Speech Production (ISSP). International Seminar on Speech Production (ISSP-11), June 20-23, Montréal, Canada, Online, 6/2011.
Abstract
It is well-known that gravity and head position can have a significant influence on vocal
tract shape. This posture effect has been observed by contrasting articulatory data obtained
from the same speakers in different postures within or across acquisition modalities.
Previous studies have compared velum height during English vowels using upright
cineradiography and supine MRI (Whalen, 1990); vowels and running speech using
upright and supine EMA (Tiede et al., 1997); jaw movement during CVC sequences
in upright, supine, and prone position using optical point-tracking (Shiller et al., 1999);
Japanese vowels, CV sequences, and running speech using upright and supine X-ray microbeam
(Tiede et al., 2000); English word sequences using upright and supine ultrasound
tongue imaging (Stone et al., 2002, 2007); Japanese vowels using upright and supine MRI
in an open scanner (Kitamura et al., 2005); and Swedish vowels and sustained consonants
using supine and prone MRI (Engwall, 2006).
While this prior work indicates that for some speakers, gravity and posture have
a pronounced effect on articulation, the exact nature of this effect is not always fully explored.
In particular, acoustic feedback, as well as the relevance of individual articulators
for a given vocal tract target configuration, may have an impact on how the posture effect
manifests.
In this study, we systematically explore the posture effect using 3D electromagnetic
articulography (EMA) data of sustained and dynamic speech produced in upright
and supine position, taking articulatory relevance into account. In fact, one goal is to
replicate as closely as possible the MRI acquisition procedure to show the main effects on
articulation and acoustic during the production of sustained vowels.
In this work, we present the experimental setup to acquire EMA data in both upright
and supine position. We focus particularly on the main differences in both positions
regarding the place of articulation and the dynamics (the characteristics of the shifting in
articulatory trajectories).
Since our final goal is to define a mapping function by which data from one posture
may be transformed into another, this study provides helpful insight toward this goal.
In fact, the posture effect should be accounted for in any speech production research involving
the spatial alignment (registration) of data obtained from modalities with different
posture (even from the same speaker), and we expect that our results may facilitate such
registration procedures.