1 SSML Extensions for TTS in Indian Languages II workshop on Internationalizing SSML May 2006, Greece Nixon Patel and Kishore Prahallad Bhrigus Inc. Hyderabad, India IIIT Hyderabad, India

© Copyright 2006, Bhrigus Software Private Limited. 2 About Bhrigus Collaborative Efforts between Bhrigus and IIIT Hyderabad Nature of Indian language scripts – convergence and divergence Issues across TTS rendering in all these languages Proposed solutions/tags: Syllable Element Alien Element Dialect Element Topics

© Copyright 2006, Bhrigus Software Private Limited. 3 Bhrigus voice & data solutions

© Copyright 2006, Bhrigus Software Private Limited. 4 Established :2002 Business : Providing IVR, Speech & Enterprise solutions to BFSI, Telco’s, contact centers & manufacturing companies. Key Customers : Hewitt Associates, AT&T, Pfizer, Merrill Lynch, Union pacific railroad, CDIA, South western energy, Orange county, Stryker SEI CMM Level 4 Process Implementation undergoing, ISO 9001: 2000 – KPMG certified. About Bhrigus

© Copyright 2006, Bhrigus Software Private Limited. 5 Playing a leadership role in the development of ASR and TTS for all official Indian languages to provide voice solutions for Indian market Collaborations: IIIT Hyderabad, & Carnegie Mellon University 10 member team + board of advisors 3 PhDs and 4 Masters Synthesis team, Recognition team, Linguist team and Language resources team Initiating SSML and VXML chapters in India Speech and Language Technology Bhrigus

© Copyright 2006, Bhrigus Software Private Limited. 6 Bhrigus Inc. Hyderabad – Voice based solution providers IIIT Hyderabad – one of the leading universities in India doing speech research Telugu TTS – Collaborative Efforts between Bhrigus Inc. and IIIT Goal: Develop ASR and TTS for all official Indian languages Collaborative Efforts

© Copyright 2006, Bhrigus Software Private Limited. 7 Basic units of the writing system are Aksharas An Akshara is an orthographic representation of a speech sound Akshara is syllabic in nature, typical forms are V, CV, CCV and CCCV (C – consonant, V – vowel) Always ends with a vowel (or nasalized vowel) in written form ~1652 dialects/native languages 22 languages officially recognized Nature of Indian Language (IL) Scripts

© Copyright 2006, Bhrigus Software Private Limited. 8 Aksharas are syllabic in nature Common phonetic base Share a common set of speech sounds across all languages Fairly good (though not exact) correspondence between sequence of Aksharas and the corresponding sequence of sounds Often referred to as Letter-to-sound rules Written from left-to-right as in European languages Words are separated by space as in European languages Convergence of IL Scripts

© Copyright 2006, Bhrigus Software Private Limited. 9 Each IL has its own script All IL share a common phonetic base – however, Phonotactics in each IL are different from each other IL are non-tonal languages unlike eastern languages such as Chinese Divergence of IL Scripts

© Copyright 2006, Bhrigus Software Private Limited. 10 Unicode Useful for *rendering* the Indian language scripts Not suitable for keying-in through QWERTY key board Not suitable to build modules such as text-normalization (can’t see the Unicode characters on many editors) Itrans-3 / OM - A transliteration scheme by IISc Bangalore, India and Carnegie Mellon University Useful for *keying-in and store* the scripts of Indian language using QWERTY keyboards Useful for processing and writing modules/rules for letter-to- sound, text normalization etc. How to represent Indian language Scripts

© Copyright 2006, Bhrigus Software Private Limited. 11 Itrans-3 / OM Notation

© Copyright 2006, Bhrigus Software Private Limited. 12 Developed from the user readability aspects – Easier to read and type It is case-insensitive. This scheme is phonetic in nature, the characters corresponds to the actual sound that is being spoken. Thus a single transliteration scheme is used for all the Indian languages, as they share the same set of sounds. Each character (corresponding to a phone/sound) is not more than three letters length. Adapted across Universities in India/Abroad and some industrial labs such as Bhrigus Inc. Why Itrans-3/OM?

© Copyright 2006, Bhrigus Software Private Limited. 13 TTS should be able to pronounce words as Akshara (syllable) by Akshara (syllable) Languages have heavy influence of English (alien) words Alien words occur in between the sentences Each language has its own dialect Issues in TTS rendering in IL

© Copyright 2006, Bhrigus Software Private Limited. 14 naatoo Ph attribute specifies phoneme/phone string Rendering “n” “aa” “t” “oo” individually does not make sense to the native speakers of Indian languages Sounds needs to be rendered in terms of syllables SSML Tag: Phoneme Element

© Copyright 2006, Bhrigus Software Private Limited. 15 naatoo Render “naa” and “too” which are Aksharas (syllables) Syllable Element

© Copyright 2006, Bhrigus Software Private Limited. 16 Informal experiments suggested 33% of errors of TTS of IL occur while rendering alien (non-native) words Such alien words could be automatically detected due to syllabic properties of the Indian languages Motivation for Loan Word

© Copyright 2006, Bhrigus Software Private Limited. 17 BANK has to be pronounce as /B/ /AE/ /N/ /K/ /AE/ phoneme does not exist in Indian language phone set baank Alien (non-native) words could be rendered using different pronunciation dictionaries or letter-to-sound rules Example of loan word

© Copyright 2006, Bhrigus Software Private Limited. 18 Each language has its own dialect TTS should be able to handle dialects without unloading the language resources Dialect Element

© Copyright 2006, Bhrigus Software Private Limited. 19 yekkad’iki vel’laali Dialect Element

© Copyright 2006, Bhrigus Software Private Limited. 20 Bhrigus Inc. Hyderabad taking lead position to develop ASR and TTS for Indian languages Proposed elements for SSML extensions Conclusions

© Copyright 2006, Bhrigus Software Private Limited. 21 References 1. Prahallad Lavanya, Prahallad Kishore and GanapathiRaju Madhavi, A Simple Approach for Building Transliteration Editors for Indian Languages, Journal of Zhejiang University Science, vol.6A, no.11, pp , Oct 2005.