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Fricatives + Voice Onset Time

Fricatives + Voice Onset Time. March 31, 2014. In the Year 2000. Today: we’ll wrap up fricatives… and then move on to stops. This Friday, there will be one final transcription exercise. On Bengali, Quebecois French, and Arabic. I just posted it right before class. Acoustic Enhancement.

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Fricatives + Voice Onset Time

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  1. Fricatives + Voice Onset Time March 31, 2014

  2. In the Year 2000 • Today: we’ll wrap up fricatives… • and then move on to stops. • This Friday, there will be one final transcription exercise. • On Bengali, Quebecois French, and Arabic. • I just posted it right before class.

  3. Acoustic Enhancement • Note: is post-alveolar and [s] is alveolar •  more space in vocal tract in front of • including a “sub-lingual cavity” • This “filter” of resonates at lower frequencies • In English, this acoustic distinction is enhanced through lip rounding for • this extends the vocal tract • further lowers the resonant frequencies of

  4. The Sub-lingual Cavity • Let’s check the videotape...

  5. Behind the Constriction [s] • Let’s check the ultrasound…

  6. Other Examples • Susie and David say “speech”: • Also: Where the shtreets have no name • And: Tina Fey • Note: there are no word-initial /sr/ sequences in English. • “shriek” *“sreek”

  7. Polish • Note: lip-rounding can be used to enhance other fricative contrasts • In Polish, it enhances the contrast between (post-)alveolar and dental fricatives • the (post-)alveolars have the rounding

  8. Polish, continued • Polish also has what are known as alveolo-palatal fricatives. • = constriction in the post-alveolar region • + raised tongue in the palatal region (behind the fricative)

  9. Polish Sibilants

  10. vs.

  11. Palatography [kasa]

  12. Palatography

  13. Polish Clusters • Just for kicks...

  14. Four Fricatives

  15. Mandarin Sibilants • Mandarin Chinese also has dental, post-alveolar and alveolo-palatal sibilant fricatives. • The post-alveolars are sometimes retroflex

  16. Mandarin

  17. Before I forget… • There are two remaining fricative symbols in the IPA that we have yet to learn. Some dialects of English still have a voiceless labio-velar fricative (a voiceless /w/): 2. In Swedish, there is a fricative which combines the articulations of post-alveolar and velar [x]:

  18. Affricates • Affricates are transcribed as stop-fricative sequences • Acoustically, amplitude rises faster in affricates than in plain fricatives • “rise time” • Phonologically, affricates are [-continuant]

  19. Affricate Typology • More numbers from the UPSID database: • 522 affricates in 316 languages • 141 • [ts] 95 • 80 • [dz] 30 • 485 affricates have sibilant fricatives • Other affricate types are rarer: • [pf] (German) [tx] (Navajo)

  20. Fricative vs. Affricate “shy” “chime”

  21. Polish, Again • Polish contrasts affricates with stop + fricative sequences

  22. Stop + Fricative vs. Affricate

  23. Fricative Acoustics Summary • Turbulence provides the source of fricative noise • Voiced fricatives also have a sound source at the glottis • Obstacle turbulence tends to be louder than channel turbulence • Sibilants are particulary high in intensity • The filter of fricative turbulence noise changes depending on the place of articulation • sibilants: very short filter, emphasizing high frequencies • labials: essentially no filter (flat spectrum) • back fricatives: longer, more vowel-like filter • Affricates: stop-fricative sequences with shorter rise time

  24. Review: Stops and Voicing • Stops • Three stages: close, maintain, release • Pressure build-up behind closure • “Release Burst” • Voicing • Vocal folds are lightly brought together (adducted) • Sub-glottal pressure higher than supra-glottal pressure • Airflow through glottis causes cycle of vocal fold opening and closing • Voiceless: k > t > p Voiced: b > d > g

  25. It’s not that simple • The voicing of stops is difficult, so the contrast between voiced and voiceless stops often takes a different form • Making use of a different property: aspiration • An aspirated stop has the following timing: • Stop closure is made • Airflow builds up pressure behind closure • Closure is released (with a “burst”) • Air flows unimpeded through glottis (“aspiration”) • Vocal folds close; voicing begins

  26. An Aspirated Stop: [phœt] aspiration release burst [t] release burst voicing (vowel) [t] closure

  27. An Unaspirated Stop: [pœt] voicing (vowel) release burst

  28. A Voiced Stop: [byt] release burst voicing (closure) voicing (vowel)

  29. Voice Onset Time • Voice Onset Time (VOT) is defined as the length of time between the release of a stop closure and the onset of voicing. • For aspirated stops--voicing begins after the release, so: • VOT  50 - 150 milliseconds • For unaspirated stops--voicing begins at the release, so: • VOT  0 - 20 milliseconds • For voiced stops--voicing begins before the release, so: • VOT < 0 milliseconds • (VOT can be negative)

  30. Thai Stops • In stressed onset position, English distinguishes between: • unaspirated and aspirated stops. • Languages like French, Dutch and Spanish distinguish between: • voiced and voiceless unaspirated stops. • Thai splits up the VOT continuum into three parts: • voiced, voiceless unaspirated, voiceless aspirated

  31. Thai Stops

  32. [ba] [pa]

  33. English Stop Contrasts • In onset position: • /p/ is voiceless aspirated • /b/ is voiceless unaspirated • In medial position (between voiced segments): • /p/ is voiceless unaspirated • /b/ is voiced • After /s/, in the same syllable: • only voiceless unaspirated stops (no contrast)

  34. Beak, Peak, Speak

  35. Rabid vs. Rapid

  36. English Stop Contrasts 4. In syllable-final position: • vowels preceding /p/ are short • vowels preceding /b/ are longer • /p/ closure tends to be longer than /b/ closure • Moral of the story: • Phonological voiced vs. voiceless contrast in English is abstract • It may exhibit different phonetic manifestations • Phonemes vs. Allophones

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