A new speech analysis technique to improve the performance of an Automatic Speech Recognition system for people with disabilities

This thesis aims to discuss the problem of dysarthria, in particular its im- plications and causes. Since the major effect on people affected by dysarthria is the reduction of their social interaction, the purpose of this thesis is to investigate a possible aid system through the implementation of the current technology. The aid system hereby proposed is composed of several elements. The one that plays a crucial role is the “Automatic Speech Recognition (ASR)”, which is responsible for the transcription of audio signal in sequences of words. The accuracy of speech recognition is excellent with unimpaired speech, but it is hard to recognize confusable words or discontinuous speech, which characterizes dysarthric people. As a result, dysarthric people require major innovations in the speech research field. An in-depth analysis of ASR systems has allowed us to understand the nature of the poor performance of these systems on dysarthric speech. There- fore it is necessary to find a new type of voice features that could improve the performance of the ASR system. Several experiments have been carried out using speeches of five people with disabilities. The results achieved have allowed us to develop a new tech- nique of speech analysis and a consequential improvement which goes from 31% to 81%, depending on the user to be analysed