Virtual Storytelling: Emotions for the narrator

The development of virtual story-telling is an ever ongoing process. As long as it does not perform on the same level as a human storyteller, there is room for improvement. The Virtual Storyteller, a project of the HMI department of the University of Twente, uses a Text-to-Speech application that creates synthetic speech from text input. It is definitely not a trivial matter to make synthetic speech sound human, especially when story-telling is involved. There are so much facets of story-telling where storytellers use their voice in order to enhance their performance. This thesis describes the study of how storytellers use their voice in order to convey the emotions that characters in the story are experiencing; specifically how the storyteller changes his voice to make a character say something in an emotional way. An experiment has been conducted to identify the emotional charge in fragments of speech by story-characters. These fragments are then analysed in an attempt to find out how the emotional charge is linked to the way the storyteller changes his voice. The analysis is then used in the creation of a model that is used by the Text-to-Speech application to synthesise emotional speech instead of neutral speech. This model is implemented in an open-source Text-to-Speech application that uses a Dutch voice. This allows the Virtual Storyteller to create tekst marked with an emotion, which is then used to synthesise emotional speech.