The human face is interesting and challenging mainly because of its familiarity. Essentially, it is the part of the human body that is used to recognize individuals. As well as the face, the speech is an important instrument for human communication, allowing the exteriorization of thoughts and the definition of emotions. Together, speech and face are the main elements of interactivity among human beings. However, the natural and faithful reproduction of the peculiarities of these elements in the computational universe is not a simple task, constituting topics of research in diverse areas, particularly in facial animation.
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Among the diverse types of facial animation systems developed, those that involve the facial animation of the virtual character combined with speech synchronization are distinguished as directly related to this work. These kinds of systems are known as \textit{talking head} or \textit{talking face}.
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For the development of a talking head system, it is necessary to identify the possible approaches for the speech and face modeling. The models used will influence not only the way that the animation is performed, but will also affect the system`s interactivity. An important contribution of the present master thesis is the study of several possible approaches for the main elements and the proposal of taxonomy for the classification of the talking head systems.
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From the proposed taxonomy and making use of one approach for each analyzed parameter, an application was developed that receives as input a text composed by the character 4s speech and genus, language and emotion parameters, and it generates as output, in real time, the animation of a virtual character uttering the input text with speech synchronization and expressiveness. The system developed, called ``Expressive Talking Heads'', explores the naturalness of facial animation and it seeks to offer the user a real-time interactivity interface. The ``Expressive Talking Heads'' system can run as a stand-alone application or connected to web browsers. It was designed and developed to provide a platform independent solution of platform- and operating system-independent solution.