A text-to-speech (TTS) system converts normal language text into speech. The quality of a speech synthesizer is judged by its similarity to the human voice and by its ability to be understood.

The population group with the most acute need for speech enabled technologies are visually impaired people. TTS is an essential technology enabling them to use computer applications, browse the internet and commu-nicate via e-mail. Some of them are advanced computer users using English TTS, but majority do not have sufficient English skills. Attempts to use English TTS for reading and preparing Latvian texts have failed due to principal differences in Latvian and English pronunciation. Latvian text pronounced by English TTS is practically incomprehensible even by the most tolerant and striving users.

Tilde has an experience in Speech Synthesis technology development since the end of 90's. Possibility to pronounce Latvian words and texts are also included in our product Tildes Birojs since 2002.

In 2005 Tilde together with Latvian Society of the Blind started a project with primary goal to address the needs of visually impaired people using computers in Latvian. The architecture of the system covers the traditional TTS transformation, performing text normalization, grapheme-to-phoneme conversion, prosody generation, and waveform synthesis. Now it is available to anyone visually impaired people in Latvia for free.