There are several open-source Tamil Text to Speech Synthesizers (TTS) available to date. Google uses one of these behind the scenes; we may wonder which one. Some of these have previously been reviewed by others at Azhagi and elsewhere on Tamil interwebs.
- eSpeak (Rule based synthesizer), GPL licensed (technique formant LPC analysis based)
- Festival (Univ of Endinbrugh)(Tamil voice added on Feb, 2015), BSD like license.
- Research carried out by IISc team lead by Prof. A.G. Ramakrishnan
- tamil-tts by Prof. Vasu Renganathan, GPL (technique unit selection based)
- Android-tts – hack the English TTS to speak Tamil by transliteration
- This is a hack suggested by yours truly;
- e.g. to speak the phrase, “சும்மா இருக்கியா?” we use the English TTS via the transliteration, “Summaa Irukkiyaa?”. Clearly this maybe sub-optimal but work as a hack.
Opinion : While there are purpoted speech synthesizers in Tamil from academic government (tax-payer) funded projects like SSN-IIT collaboration, they are not publicly available or easily licensable. It is a situation that needs to be remedied.
Linguistic Aspects: One of key issues that make Tamil TTS a relatively easy goal is because the front-end is easily achieved due to the phoneme-orthography of Tamil language – i.e. Tamil language is itself a “phonetic language” where written spelling and phonetic/spoken forms are identical. This is not so in case of English and European languages like French where there are silent words, and exceptions to rules almost all the time. Tamil language has few exceptions if any.
The back-end of the TTS engine is usually formed by LPC analysis or other source-filter separation algorithms which is an exciting and continually engaging problem for Signal processing engineers, computer scientists, and computational linguists.
Further research for Tamil TTS should improve on the naturalness and ability to include these wonderful tools of previous generation of engineers into our applications for mobile and desktop devices. Google scholar is your friend – start here!.