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CS626-449: Speech, NLP and the Web/Topics in AI. Pushpak Bhattacharyya CSE Dept., IIT Bombay Lecture-23: Phonetics contd. (lecture 21, 22 taken by Anup on Graphical Models). Phonteic Symbols and IPA notation. IPA: vowels. Need for Phonetic Transcription.
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CS626-449: Speech, NLP and the Web/Topics in AI Pushpak Bhattacharyya CSE Dept., IIT Bombay Lecture-23: Phonetics contd. (lecture 21, 22 taken by Anup on Graphical Models)
Need for Phonetic Transcription • Not every language has a writing system • Not every writing system represents sounds (Chinese characters) • Not every sound-representing writing system represents segments (Japanese hiragana and katakana) • The representation of speech sounds in segment-representing writing systems is problematic because it is highly inconsistent (English)
Sound to Symbol relationship is arbitrary • One letter, one sound: b represents [b] in ball, breathe, cab • A set of letters, one sound: architect, shampoo, teeth, though, cheese, enough • One letter, many sounds: a represents [æ] in cat, [ej] in cave, [ɑ] in car, [ə] in alike • One sound, many letters: [i] represented differently in sea, see, he, key, believe, receive, people, machine • One letter, no sound: knight (cf. night) , write (cf. right, rite), comb
Classification • Manner of articulation • Place of articulation • Voicedness
The sound producing system • Lungs: the source of air • Larynx: the source of noise/sound • Vocal cords/folds • Glottis • Vocal tract: the source of resonance/ the filters • Pharynx • Oral cavity • Nasal cavity
Articulation of consonants: Larynx action/glottis state • Vocal cords are pulled apart. The air passes freely through the glottis. This is called the voicelessness state and sounds produced with this configuration of the vocal cords are called voiceless: p t k f θ s ʃ tʃ • Vocal cords are pulled close together. The air passing through the glottis causes the vocal cords to vibrate. This is called the voicing state and sounds produced with this configuration of the vocal cords are called voiced: b d g v ð z ʒ dʒ • Vocal cords are apart at the back and pulled together at the front. This is called the whisper state. • Vocal cords assume the voicing state but are relaxed. This is called the murmur state.
Place of Articulation (1/2) • Labial: closure or near-closure of the lips • bilabial: p b m • labiodental: f v • Dental: tip of the tongue against upper teeth or between them • interdental: θ ð • Alveolar: tongue against or near alveolar ridge • t d s z n l r • Alveopalatal: body of tongue on or near area behind alveolar ridge • ʃ ʒ tʃdʒ • Palatal: body of the tongue on or near the palate • j
Place of articulation (2/2) • velar: back of the tongue touching or near the velum • k g ŋ • Uvular: tongue touching or near the uvula • Pharyngeal: retraction of the tongue or constriction of pharynx • glottal: vocal folds as primary articulation: h ʔ