1. CS460/626 : Natural Language Processing/Speech, NLP and the Web (Lecture 31–Inside and Outside probabilities; PCFG training; start of phonetics and phonology) Pushpak Bhattacharyya CSE Dept., IIT Bombay 29 th March, 2011

2. PCFG: inside and outside probabilities

3. Inside probability β Sentence probability

4. Calculation of β

5. Outside probability α Sentence probability

6. Calculation of α

7. PCFG Training

8. EM Algorithm for training

9. Phonetics and Phonology

10. Morphology to Phonology: an exercise The plural morpheme: -s: /s/ (cats) /z/ (dogs) /iz/ (bushes) Which sound should occur where?

11. Phonetics and Phonology Phonetics: The study of speech sounds Articulatory Acoustic Auditory Phonology: the structure and patterning of sounds Phonetic Transcription: A writing system for representing speech sounds

12. The need for phonetic transcription Eccentricity of English Spelling Put/Putt Car/Kite Rough/Puff Fish can be spelt ‘ghoeti’. How? A language for talking about other/newly discovered languages New languages without a writing system are discovered often

14. Classification Manner of articulation Place of articulation Voicedness

15. Stops /p/ - voiceless bilabial /b/ - voiced bilabial /t/ - voiceless alveolar /d/ - voiced alveolar /k/ - voiceless velar /g/ - voiced velar

16. Fricatives /f/ /v/ /th/ /dh/ /s/ /sh/ /zh/ /h/

17. Affricates /ch/ /jh/

18. Nasals /m/ /n/ /ng/

20. The plural sound Cats, racks … /s/ dogs, rags … /z/ Bushes, classes … /iz/ Hypotheses?

21. A kudo to each of you! Kudos: pronounced with an /s/ sound at the end Misinterpreted as a plural One kudo, many kudos Pronunciation becomes kudo/z/!