Author(s):
Vasconcelos, Maria João
; Ventura, Sandra Moreira Rua
; Freitas, Diamantino Rui
; Tavares, João Manuel
Date: 2010
Persistent ID: http://hdl.handle.net/10400.22/3528
Origin: Repositório Científico do Instituto Politécnico do Porto
Subject(s): Modelling and simulation; iomedical engi neering systems for future diagnosis & therapy; Image analysis
Description
The first and second authors would like to thank the support of the PhD grants with references
SFRH/BD/28817/2006 and SFRH/PROTEC/49517/2009, respectively, from Fundação para a
Ciência e Tecnol
ogia (FCT).
This work was partially done in the scope of the project “Methodologies to Analyze Organs from
Complex Medical Images – Applications to Fema
le Pelvic Cavity”, wi
th reference PTDC/EEA-
CRO/103320/2008, financially supported by FCT. Since ancient times, speech production has attracted particularly interest aiming at reaching a
deeper understanding of the mechanisms involved
by considering both morphological and speech
acoustic aspects. The central anatomical aspects
and the physiology of the human vocal tract are
common to all individuals. However, speech
production is an exceptionally complex and
individualistic process. Therefore, the modelling of
the mechanisms involved in speech production
implies the enclosing of adequate flexibility in order to consider individual variations accurately. In
this work, the shape of vocal tract in the articulation of some European Portuguese (EP) sounds is
evaluated by using deformable models applied in Magnetic Resonance (MR) images. Additionally,
the deformable models built are afterwards used to automatically segment the modelled vocal
tract in MR images.
From the imaging modalities that have been take
n into consideration in order to study the vocal
tract shape and articulators, Magnetic Resonance Imaging (MRI) has been the most commonly
accepted. Actually, the use of MRI allows the study of the entire human vocal tract and, in
addition, the quality and resolution of soft-tissues and the use of non-ionizing radiation are key
advantages presented by MRI.
The deformable model used, commonly known as Point Distribution Model (PDM), was built from a
set of training images acquired du
ring artificially sustained articulations of 21 EP sounds. In a brief
review, one can assert that PDM’s are obtained by
a statistical analysis done on the co-ordinates
of landmark points that represent the shape to be
modelled: after aligning the training shapes, a
Principal Component Analysis is performed in order to obtain the model mean shape and the
modes of variation relatively to this mean shap
e. Combining the geometrical information of the
PDM with the grey levels of the landmark points us
ed in its building one can build the Active Shape
Models (ASM) and the Active Appearance Models (AAM). With these enhanced models is possible
to segment the modelled shape in new images in a fully automated way.
From the experimental results obtained in this
work, one may conclude that the PDM built could
efficiently characterize the behaviour of the voca
l tract shape during the production of the EP
sounds studied with MRI. Furthermore, one can ve
rify that the ASM and the AAM built could be
used to segment the modelled vocal tract in MR images in a successful manner. Therefore, the
deformable models built should be considered towards the efficient and automatic study of the
vocal tract during speech production with MRI,
in particular for enhanced speech production
simulation and speech rehabilitation therapies.