LSESpeak: A spoken language generator for Deaf people

This paper describes the development of LSESpeak, a spoken Spanish generator for Deaf people. This system integrates two main tools: a sign language into speech translation system and an SMS (Short Message Service) into speech translation system. The first tool is made up of three modules: an advanced visual interface (where a deaf person can specify a sequence of signs), a language translator (for generating the sequence of words in Spanish), and finally, an emotional text to speech (TTS) converter to generate spoken Spanish. The visual interface allows a sign sequence to be defined using several utilities. The emotional TTS converter is based on Hidden Semi-Markov Models (HSMMs) permitting voice gender, type of emotion, and emotional strength to be controlled. The second tool is made up of an SMS message editor, a language translator and the same emotional text to speech converter. Both translation tools use a phrase-based translation strategy where translation and target language models are trained from parallel corpora. In the experiments carried out to evaluate the translation performance, the sign language-speech translation system reported a 96.45 BLEU and the SMS-speech system a 44.36 BLEU in a specific domain: the renewal of the Identity Document and Driving License. In the evaluation of the emotional TTS, it is important to highlight the improvement in the naturalness thanks to the morpho-syntactic features, and the high flexibility provided by HSMMs when generating different emotional strengths.