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Lehlohonolo Mohasi Supervisors: Prof. Mqhele E. Dlodlo Prof. Mbulungeni Madiba Co-Supervisor: Prof. Daniel Mashao. A bilingual corpus-based TTS system as a foreign language learning tool. Outline. Current Situation Problem Solution Evaluation Conclusion Future Work. 2.
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Lehlohonolo Mohasi Supervisors: Prof. Mqhele E. Dlodlo Prof. Mbulungeni Madiba Co-Supervisor: Prof. Daniel Mashao A bilingual corpus-based TTS system as a foreign language learning tool
Outline Current Situation Problem Solution Evaluation Conclusion Future Work 2
Current Situation I don’t think so. Andiphilile neze. Ana u ea sekolong tsatsing lee? 3
Current Situation Language Acquisition How babies learn to talk & understand language Exposure to spoken language Reading & writing learnt through instruction Second/Foreign Language Learning Not easily acquired Need voice exposure as well + instruction Different instructional methods 4
Problem Not enough voice exposure for L2 or foreign language learners. There might be exposure but there is also a need for ability to read and write for various reasons. Use of correct grammar & pronunciation in written and spoken languages. 5
Problem – Research Question How can technology be used as an effective second/foreign language learning tool?
Solution Human Language Technologies/Information Communication Technology Proposed technology -> Text-to-speech (TTS) as a second/foreign language learning tool What is TTS? Automatic conversion of written text into speech. 7
Phonemes Prosody Solution - TTS NLP Text Analysis LTS Rules Prosody Generation DSP Concatenation-based Synthesis Waveform Generation Speech Text 8
Solution - TTS • TTS Applications • Telecommunications • Visually-impaired • Deaf and Vocally Handicapped • Educational Applications • What value is TTS? • Easy voice access mode to all • Useful for the blind and illiterate • Easy way of improving language listening & speaking skills • Helps with correct pronunciation 9
Solution – Language & TTS So how do we make sense of text-to-speech technology implementation in foreign language learning? 10
Solution - Methodology • Scope • Use of 3 SA official languages – English, Sesotho & isiXhosa. • Multiconcord – Mconsal • Festival Speech Synthesis Engine • Parallel corpora selection from 1994 to date • 1 million words
Solution - Methodology • Phase 1 – Creating corpora • Creating a parallel corpora database • Tools • BITS (Bilingual Internet Text Search) • Strand • Scanner • Multiconcord • MinMark
Solution - Methodology • Phase 2 – TTS implementation • TTS database taken from parallel corpora • Limited domain synthesis • Tools • Festival Speech Synthesis Engine • Phase 3 – Web interface • Integration of Phases 1 & 2 • Tools • PHP • mySQL
Evaluation • Acoustic measurements – voice talent selection • Fundamental frequency, F0 • RMS energy for voiced and unvoiced speech • Long-term spectra • Vowel formants and bandwidths • Target costs • Concatenation costs • Functional testing - TTS-system assessment on performance for communicative purpose (intelligibility measure) 15
Evaluation • MOS (Mean Opinion Score) - general speech quality evaluation • Pleasantness * Pronunciation • Articulation * Understandability • Sound quality * Intelligibility • Listening effort
Evaluation • Groups of interest • UCT staff (n=75) • UCT students (n=75) • Medical (Rehabilitation & Doctors) • Law • Other streams • Exposure to voice access & non-exposure • Monitor over time • Results obtained from assessment exams • Use age as one variable 17
Conclusion Text-to-speech technology is a convenient and support tool - possible solution. With an increasing recognition for demographics - need for engaged learners to take full responsibility for their language learning. There is also a need for teachers who are not only language experts but who are also trained in the use of technology and who can facilitate foreign language learning. 18
Future Work • Multilingual Speech to Speech • Speech to speech takes speech processing a step further towards a voice-only computer interface. • Incorporates ASR & TTS • Enables computing devices to first understand spoken language, then analyze the utterance through natural language processing, and finally formulate and utter a response through synthesized speech. 19
Thank You QUESTIONS?? SUGGESTIONS?? 20