Proposal of a Speech-synthesis Interface for Speech Disorders by using a Pointing Device

Abstract

A speech production substitute was proposed for speech disorders that are caused by dysfunction of articulation organs. In this substitution method, the speech synthesis is controlled by a position and a motion of a pen or a finger put on a pointing device without any key input. Therefore, our method allows the users to produce rhythms and prosodies of voices, different from conventional methods that use only text. The first and the second formant frequencies were two dimensionally assigned to the plane of a pen-tablet that corresponds to a position of tongue. First, it was investigated how continuous vowels are heard by tracing the pen-tablet. After a few hours training, a subject with speech disorder succeeded to produce some continuous speech sentences that were apparently perceived as if they have some consonants. Next, in order for the users to easily find the optimal formant transitions to produce the desired consonants, "Guiding Lines" were superimposed on the pen-tablet display. Direction and length of the guiding lines were determined by an "Expanded Locus Theory". From the evaluation tests, it was ascertained that the users may more easily produce the arbitral sentences by tracing the guide lines than conventional one. However, it was still difficult to perceive some consonants having random noise component such as /s/, /h/ and /z/. How the noise component should be added and controlled by user's finger was discussed.