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Voice Onset Time + Voice Quality

Voice Onset Time + Voice Quality. November 26, 2012. The Future. More assignments! For Friday: VOT + fricative transcription For next Monday: Production Exercise #4. This week: the basics of obstruent acoustics On Wednesday: cues for place of articulation.

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Voice Onset Time + Voice Quality

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  1. Voice Onset Time+ Voice Quality November 26, 2012

  2. The Future • More assignments! • For Friday: VOT + fricative transcription • For next Monday: Production Exercise #4. • This week: the basics of obstruent acoustics • On Wednesday: cues for place of articulation. • Next week: sonorant acoustics • approximants and nasals • Also on Monday of next week: • Evaluations of instruction

  3. 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

  4. 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

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

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

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

  8. 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)

  9. 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

  10. Thai Stops

  11. [ba] [pa]

  12. 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)

  13. Beak, Peak, Speak

  14. Rabid vs. Rapid

  15. 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

  16. Complication #1 • Fricatives and affricates may also be aspirated • In these cases, VOT must be calculated beginning from the offset of sibilance.

  17. Tree vs. Chree • Check ‘em out in Praat

  18. Syllable-Final • Syllable-final obstruents may also be distinguished by aspiration. Examples from Armenian • In this case, voicing does not necessarily resume after aspiration

  19. Syllable-Final Spectrograms release burst aspiration

  20. Practical Point: Pop Filters • When recording speech digitally, the airflow of aspiration can cause “pops” to appear in the recording. • A result of clipping the waveform • If you have some extra cash, this problem can be solved by placing a pop filter in front of the microphone. • Otherwise, make sure the microphone is not directly in front of the speaker’s lips.

  21. Voice Quality • Note that there are three primary types of vocal fold vibration: • modal • vocal folds lightly adducted; flow of air causes periodic opening and closing of folds (“trilling”) • breathy • vocal folds slightly apart; flow of air makes folds “wave” in the wind • creaky • vocal folds tensely adducted; low airflow causes irregular, low frequency voicing

  22. breathy [] creaky []

  23. Modal to Creaky [ ]

  24. Voice Quality Movies Source: http://www.ling.mq.edu.au/speech/physiology/movies/fibrescope/index.html

  25. Contrasts • Gujarati contrasts breathy voiced vowels with modal voiced vowels: • Jalapa Mazatec has a three-way contrast between modal, breathy and creaky voiced vowels:

  26. Voiced Aspirated • Some languages distinguish between (breathy) voiced aspirated and voiceless aspirated stops and affricates. • Check out Hindi:

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