Browsing by Author "Freitas, Diamantino Rui"
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- Analysis of tongue shape and motion in speech production using statistical modelingPublication . Vasconcelos, Maria João; Ventura, Sandra Moreira Rua; Tavares, João Manuel; Freitas, Diamantino RuiThe mechanisms of speech production are complex and have been raising attention from researchers of both medical and computer vision fields. In the speech production mechanism, the articulator’s study is a complex issue, since they have a high level of freedom along this process, namely the tongue, which instigates a problem in its control and observation. In this work it is automatically characterized the tongues shape during the articulation of the oral vowels of Portuguese European by using statistical modeling on MR-images. A point distribution model is built from a set of images collected during artificially sustained articulations of Portuguese European sounds, which can extract the main characteristics of the motion of the tongue. The model built in this work allows under standing more clearly the dynamic speech events involved during sustained articulations. The tongue shape model built can also be useful for speech rehabilitation purposes, specifically to recognize the compensatory movements of the articulators during speech production.
- Application of MRI and Biomedical Engineering in Speech Production StudyPublication . Ventura, Sandra Moreira Rua; Freitas, Diamantino Rui; Tavares, João ManuelSpeech production has always been a subject of interest both at the morphological and acoustic levels. This knowledge is useful for a better understanding of all the involved mechanisms and for the construction of articulatory models. Magnetic resonance imaging (MRI) is a powerful technique that allows the study of the whole vocal tract, with good soft tissue contrast and resolution, and permits the calculation of area functions towards a better understanding of this mechanism. Thus, our aim is to demonstrate the value and application of MRI in speech production study and its relationship with engineering, namely with biomedical engineering. After vocal tract contours extraction, data were processed for 3D reconstruction culminating in model construction of some of the sounds of European Portuguese. MRI provides useful morphological data about the position and shape of the different speech articulators, and the biomedical engineering computational tools for its analysis.
- Imaging of the Vocal Tract based on Magnetic Resonance TechniquesPublication . Ventura, Sandra Rua; Freitas, Diamantino Rui; Tavares, João ManuelMagnetic resonance (MR) imaging has been used to analyze and evaluate the vocal tract shape through different techniques and with promising results in several application fields. Our main purpose is to demonstrate the relevance of MR and techniques of image processing in the analysis of vocal tract.
- Magnetic resonance imaging of the vocal tract: techniques and applicationsPublication . Ventura, Sandra Moreira Rua; Freitas, Diamantino Rui; Tavares, João ManuelMagnetic resonance (MR) imaging has been used to analyse and evaluate the vocal tract shape through different techniques and with promising results in several fields. Our purpose is to demonstrate the relevance of MR and image processing for the vocal tract study. The extraction of contours of the air cavities allowed the set - up of a number of 3D reconstruction image stacks by means of the combination of orthogonally oriented sets of slices for e ach articulatory gesture, as a new approach to solve the expected spatial under sampling of the imaging process. In result these models give improved information for the visualization of morphologic and anatomical aspects and are useful for partial measure ments of the vocal tract shape in different situations. Potential use can be found in Medical and therapeutic applications as well as in acoustic articulatory speech modelling.
- Modelling and segmentation of the vocal tract during speech production by using deformable models in magnetic resonance imagesPublication . Vasconcelos, Maria João; Ventura, Sandra Moreira Rua; Freitas, Diamantino Rui; Tavares, João ManuelSince 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.
- Modelos morfológicos tridimensionais por IRM do tracto vocal para as principais vogais do Português EuropeuPublication . Ventura, Sandra Moreira Rua; Freitas, Diamantino RuiO entendimento da produção da fala tem sido ampla mente procurado, recorrendo à imagem por ressonância magnética (IRM), mas não é totalmente conhecido, particularmente no que diz respeito aos sons do Português Europeu (PE). O principal objectivo deste estudo foi a caracterização das vogais do PE. Com base na IRM recolheram-se conjuntos de imagens bidimensionais, em cinco posições articulatórias distintas, durante a produção sustentada do som. Após extracção de contornos do tracto vocal procedeu-se à reconstrução tridimensional, constatando-se que a IRM fornece in formação morfológica útil e com considerável precisão acerca da posição e forma dos diferentes articuladores da fala.
- Morphological Differences in the Vocal Tract Resonance Cavities of Professional Voices: A MRI-based StudyPublication . Ventura, Sandra Rua; Freitas, Diamantino Rui; Ramos, Isabel Maria; Tavares, João ManuelThe processes that take place during singing and acting are complex. However morphological and dynamic studies of the vocal tracts during speech have been gaining greater attention, mainly due to the rapid technical advances being made with Magnetic Resonance Imaging (MRI) and image analysis and processing techniques
- Morphological Dynamic Study of Human Vocal TractPublication . Ventura, Sandra Rua; Freitas, Diamantino RuiMagnetic resonance imaging (MRI) has been successfully used in speech research, with the development of high B-value units and ultra-fast acquisition sequences, to obtain morphological and dynamic data of the vocal tract. This knowledge is useful for the understanding of speech mechanisms and can, in particular be employed for speech synthesis. The aim of our study was a combination of the morphological and dynamical characterizations of speech, resulting in the production of 3D articulatory models of some relevant Portuguese sounds and syllables. A set of static images in stacks and dynamic sequences were collected during the experiments from subjects that were instructed to vocalize during the acquisition, exploring the capabilities of the equipment. Analysis of the image stacks allowed the extraction of the vocal tract contours and a subsequent non-conventional 3D reconstruction by means of combination of orthogonal stacks allowed visualization and partial measurement of the sampled vocal tract shape.
- Morphological Dynamic Study of Human Vocal TractPublication . Ventura, Sandra Rua; Freitas, Diamantino RuiWith the development of high B-value units and ultra-fast acquisition sequences, magnetic resonance imaging (MRI) has been successfully used in speech research to obtain morphological and dynamic data of the vocal tract
- Speaker-specific articulatory assessment and measurements during Portuguese speech production based on Magnetic Resonance ImagesPublication . Ventura, Sandra Moreira Rua; Vasconcelos, Maria João; Freitas, Diamantino Rui; Ramos, Isabel Maria; Tavares, João Manuel R. S.The development of two and three-dimensional magnetic resonance imaging (MRI) opened new options for a better understanding of speech production; in particular, for the articulation process, comparing with other imaging techniques, such as x-rays. Several MRI studies have been carried out considering different languages, but concerning European Portuguese the available information is far from being completely achieved. Recently, the knowledge gained with the application of deformable models in magnetic resonance images towards the automatic study of the vocal tract, has allowed an enhanced identification and description of the articulatory mechanism and its organs. Our aim is to extract and evaluate the main characteristics of the movements of vocal tract during European Portuguese speech production to achieve speaker-specific articulatory assessment from MRI. For this, we used active shape and active appearance models to identify, i.e. to segment, and simulate the vocal tracts shape in MR images and concluded that both are suitable for such tasks being the later more proficient. The findings obtained are believed to be useful for speech rehabilitation and simulation purposes, namely to recognize and simulate the compensatory movements of the articulators during speech production.Therefore, this chapter gains particular interest within the communities of speech study and rehabilitation, medical imaging and bioengineering. It is organized as follows: the introduction section starts with a literature review concerning the use, application and challenges of MRI in speech production study, in particular for speech articulation. In addition, image analysis techniques based on deformable templates, more specifically by using geometrical shapes driven by parameterized functions, are introduced. In the second section, the adopted methodology of MRI acquisition and data assessment are described. Based on this image analysis approach, in the results section the key aspects of articulatory movements during the production of relevant European Portuguese speech sounds are addressed. In the final section of this chapter, conclusions are presented and further suggestions for future work are indicated.