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Vowels (again)

Vowels (again). March 16, 2010. The Docket. Extra credit assignments to turn in… and homeworks to hand back. Today (and Thursday): some outstanding issues with understanding the acoustics of vowels The lab computer is still in the shop…

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Vowels (again)

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  1. Vowels (again) March 16, 2010

  2. The Docket • Extra credit assignments to turn in… • and homeworks to hand back. • Today (and Thursday): some outstanding issues with understanding the acoustics of vowels • The lab computer is still in the shop… • But the spectrogram reading practice will return once it’s fixed. • There’s one demo that I forgot…

  3. For the Skeptics • Sounds that exhibit spectral change over time sound like speech, even if they’re not speech • Example 2: wah pedal • shapes the spectral output of electrical musical instruments

  4. Phonetics Comes Alive! • It is possible to take spectral change rock one step further with the talk box. • Check out Peter Frampton.

  5. Back to Perturbation Theory • Basic idea #1: vocal tract resonances (formants) are the result of standing waves in the vocal tract • These standing waves have areas where velocity alternates between high and low (anti-nodes), and areas where velocity does not change (nodes)

  6. Perturbation Principles • Basic Idea #2: constriction at a velocity anti-node decreases a resonant frequency anti-node anti-node

  7. Perturbation Principles • Basic Idea #3: constriction at a velocity node increases a resonant frequency node node

  8. Labial • Constrictions in the labial region are at anti-nodes for both F1 and F2. •  Labial constrictions decrease both F1 and F2

  9. Palatal Labial • Constrictions in the palatal region are at an F2 node and near an F1 anti-node •  F1 decreases; F2 increases

  10. Velar Palatal Labial • Constrictions in the velar region are at an F2 anti-node and near an F1 anti-node •  F1 decreases; F2 decreases

  11. Pharynx Velar Palatal Labial • Constrictions in the pharyngeal region are at an F2 anti-node and near an F1 node •  F1 increases; F2 decreases

  12. Larynx Pharynx Velar Palatal Labial • Constrictions in the laryngeal region are at an F2 node and an F1 node •  F1 increases; F2 increases

  13. Different Sources • For a particular articulatory configuration, the vocal tract will resonate at a certain set of frequencies… • no matter what the sound source is. • (Remember the talk box) • Let’s see what happens when we change our sound source to a duck call…

  14. Duck Call Vowels • Now let’s filter the duck call with differently shaped plastic tubes…. • Care to make any predictions? duck call is placed here http://www.exploratorium.edu/exhibits/vocal_vowels/vocal_vowels.html

  15. Another View [i]

  16. Duck Call Spectrograms [i]

  17. Duck Call Spectra [i]

  18. How About These? duck call is placed on this side

  19. [i] vs. [e] [i] [e]

  20. [u] vs. [o] [u] [o]

  21. Philosophical Fragments • Consider the Cardinal Vowels, again. • An age-old question: • Why are the high, back vowels rounded… • And everything else unrounded? • Rounding back vowels takes advantage of an acoustic synergy… • which lowers both F1 and F2. • But is there anything wrong with rounding the other vowels?

  22. Five Vowel Spaces • Many languages have only three or five vowels, separated evenly in the vowel space in a triangle • Here’s a popular vowel space option: • i u • e o • a

  23. Five-Vowel Spaces

  24. Gujarati Vowel Space

  25. A “Bad” Vowel Space • Five vowels in a vowel system are rarely, if ever, distributed thusly: • [i] • [e] • [æ] • Why?

  26. Adaptive Dispersion Theory • Developed by Bjorn Lindblom and Johan Liljencrants • (Swedish speakers) • Adaptive Dispersion theory says: • Vowels should be as acoustically distinct from each other as possible • (This helps listeners identify them correctly) • So…languages tend to maximize the distance between vowels in acoustic space • Note: lack of ~ distinction in Canadian English.

  27. Swedish

  28. Unrounded Vowel Stats • Number of languages with the following unrounded vowels (out of 316, from the UPSID database): • i: 271 : 46 : 4 • : 54 • e: 83 : 4 • (e: 113) : 77 ( : 6) • : 116 : 6 : 4 • æ: 38 • a: 14 (a: 274) : 22

  29. Rounded Vowel Stats • Number of languages with the following rounded vowels (out of 316, from the UPSID database): • y: 21 : 6 u: 254 • : 3 : 48 • ø: 15 o: 88 • : 5 (o : 133) • œ: 7 : 100 • : 0 : 5

  30. Rounded/Unrounded • Ratio of number of languages with rounded vowels divided by number of languages with unrounded vowels, for particular parts of the vowel space: • .077 .130 63.5 • .056 • .077 22.0 • .065 (22.2) • .060 25.0 • .000 .227

  31. The Good, the Bad and the… • High, front region of the vowel space: • Unrounded vowels are preferred (good) (271) • Rounded vowels are dispreferred (bad) (21) • High, back region: • Unrounded vowels are bad (4) • Rounded vowels are good (254) • Low, back region: • Unrounded vowels are better (22) • Rounded vowels are worse (5) • Low, front region: Rounded vowels are really bad. (0)

  32. Bad Vowel #1: [y] • [y] has both labial and palatal constrictions • Why is this bad?

  33. Bad Vowel #2: [] • [] has only a velar constriction • Why is this bad?

  34. Bad Vowel #3: [] • [] has a pharyngeal and a labial constriction • Why is this bad?

  35. Really Bad Vowel #4: [] • [] has both laryngeal and labial constrictions • Why is this bad?

  36. Advanced Tongue Root • Some languages have an added articulatory feature for vowels, called advanced tongue root • found in a lot of West African languages • What are the acoustic consequences of advancing the tongue root?

  37. Ultrasound This is a speaker of Kinande. Kinande is spoken in Congo. (from Gick, 2002)

  38. Ultrasound: +ATR vs. -ATR advanced (+ATR) retracted (-ATR)

  39. ATR vowels in Akan • Akan is spoken in Ghana

  40. +ATR vs. -ATR

  41. ATR Vowel Spaces • DhoLuo is spoken in Kenya and Tanzania

  42. F3 and , revisited • English has pharyngeal, palatal and labial constrictions • These constrictions conspire to drastically lower F3

  43. F3 and , revisited

  44. Retroflex Vowels • Retroflexion is a feature which may be superimposed on other vowel articulations. • Retroflexion is contrastive in vowels in Badaga, a language spoken in southern India.

  45. Retroflex Vowel Spectrograms [be]

  46. F3 and [y] • [y] has both labial and palatal constrictions • What effect would these constrictions have on F3?

  47. [i] vs. [y] [li] [ly]

  48. Overrounded Vowels • Note: there is typically more rounding on [u] than [o] • and on [o] than • all the way down the line... • It is possible to have [u]-like rounding on lower vowels • “over-rounding” in Assamese • Assamese is spoken in Bangladesh.

  49. Overrounded Vowel Spectrograms

  50. Overrounded Vowel Spectrograms

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