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Phonetics and Speech Feature Extraction

Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 15

48 cards in “15.2 Articulatory phonetics” · whole deck

15.2 Articulatory phonetics

  1. Define articulatory phonetics.
    The study of how phones are produced as the organs in the mouth, throat and nose modify the airflow from the lungs.
  2. Trace the path of air in producing most speech sounds.
    Expelled from the lungs through the trachea (windpipe), through the larynx, then out the mouth or nose.
  3. What is the larynx?
    The “Adam's apple” or voice box; it contains the vocal folds.
  4. What are the vocal folds and the glottis?
    Vocal folds (non-technically “vocal cords”): two small folds of muscle in the larynx that can move together or apart. The glottis is the space between them.
  5. When do the vocal folds vibrate?
    When they are close together (but not tightly closed) as air passes through. If far apart, they don't vibrate.
  6. Define voiced vs unvoiced sounds, with examples.
    Voiced: made with vocal folds together and vibrating — [b], [d], [g], [v], [z], all English vowels.
    Unvoiced (voiceless): no vocal fold vibration — [p], [t], [k], [f], [s].
  7. What is the vocal tract?
    The area above the trachea; it consists of the oral tract and the nasal tract.
  8. What are nasal sounds? Examples?
    Sounds made by air passing through the nose; they use both the oral and nasal tracts as resonating cavities. English [m], [n], [ng].
  9. Contrast consonants and vowels.
    Consonants: made by restricting or blocking airflow; can be voiced or unvoiced.
    Vowels: less obstruction, usually voiced, generally louder and longer-lasting.
  10. What are semivowels? Examples?
    Sounds like [y] and [w] with properties of both: voiced like vowels, but short and less syllabic like consonants.
  11. Define place of articulation.
    A consonant's point of maximum restriction of airflow.
  12. Bilabial consonants: definition and English examples?
    Main restriction formed by the two lips coming together: [p] (possum), [b] (bear), [m] (marmot).
  13. Labiodental consonants: how made and examples?
    Bottom lip pressed against the upper teeth, air flowing through the space in the upper teeth: [f], [v].
  14. Dental consonants: how made and English examples?
    Tongue against the teeth (behind the teeth, tip slightly between them): [th] (thing), [dh] (though).
  15. What is the alveolar ridge, and which phones are alveolar?
    The portion of the roof of the mouth just behind the upper teeth. [s], [z], [t], [d] are made with the tongue tip against it.
  16. What does coronal refer to?
    Both dental and alveolar places of articulation.
  17. Palato-alveolar sounds: how made and examples?
    Blade of the tongue against the rising back of the alveolar ridge: [sh] (shrimp), [ch] (china), [zh] (Asian), [jh] (jar).
  18. How is the palatal sound [y] made?
    Front of the tongue placed up close to the palate (roof of the mouth), as in yak.
  19. What is the velum and which sounds are velar?
    The velum (soft palate) is a movable muscular flap at the very back of the roof of the mouth. Velars [k] (cuckoo), [g] (goose), [ng] (kingfisher) press the back of the tongue against it.
  20. How is the glottal stop [q] made?
    By closing the glottis (bringing the vocal folds together).
  21. Define manner of articulation.
    How the airflow restriction is made (e.g. complete stoppage vs partial blockage). Place + manner is usually enough to uniquely identify a consonant.
  22. What is a stop? What are its closure and release?
    A consonant where airflow is completely blocked for a short time, then explosively released. Closure = period of blockage; release = the explosion. Also called plosives.
  23. English voiced vs unvoiced stops?
    Voiced: [b], [d], [g]. Unvoiced: [p], [t], [k].
  24. How are nasal consonants produced (manner)?
    By lowering the velum so air passes into the nasal cavity: [n], [m], [ng].
  25. What is a fricative?
    Airflow is constricted but not cut off completely; the turbulent airflow produces a characteristic “hissing” sound.
  26. Name the English fricatives by place.
    Labiodental [f], [v]; dental [th], [dh]; alveolar [s], [z]; palato-alveolar [sh], [zh].
  27. How are palato-alveolar fricatives [sh], [zh] made?
    Tongue at the back of the alveolar ridge, forcing air through a groove formed in the tongue.
  28. What are sibilants?
    The higher-pitched fricatives: in English [s], [z], [sh], [zh].
  29. What are affricates? English examples?
    Stops followed immediately by fricatives: [ch] (chicken), [jh] (giraffe).
  30. What is an approximant? Examples?
    The two articulators are close together but not close enough to cause turbulent airflow: [y] (yellow), [w] (wood), [r], [l].
  31. What are the two ways American [r] can be formed?
    (1) Tip of the tongue extended and close to the palate, or (2) the whole tongue bunched up near the palate.
  32. Why is [l] called a lateral?
    It's made with the tongue tip against the alveolar ridge or teeth, with one or both sides of the tongue lowered so air flows over them.
  33. What is a tap or flap?
    [dx]: a quick motion of the tongue against the alveolar ridge, e.g. the middle consonant of lotus [l ow dx ax s] in American English. Many U.K. speakers use [t] instead.
  34. What are the three main parameters for describing vowels?
    Vowel height, frontness/backness (location of the tongue's highest point), and lip rounding.
  35. What does vowel height correlate with?
    Roughly with the height of the highest part of the tongue — though it's really a more accurate reflection of acoustic facts than of actual tongue position.
  36. Define front vowels and back vowels, with examples.
    Front: tongue raised toward the front (e.g. [iy]). Back: tongue raised toward the back (e.g. [uw]).
  37. [ih] vs [eh]: which has the higher tongue?
    [ih]. Both are front vowels.
  38. Define high, mid, and low vowels.
    Classified by the height of the highest point of the tongue: comparatively high, mid, or low.
  39. What is a diphthong?
    A vowel in which the tongue position changes markedly during its production. English is particularly rich in diphthongs (e.g. [ey], [ay], [aw], [oy], [ow]).
  40. On the schematic vowel chart, how do diphthongs differ from other vowels?
    Diphthongs are represented as a path; monophthongs as a point.
  41. What are rounded vowels? English examples?
    Vowels pronounced with the lips rounded (as for whistling): [uw], [ao], [ow].
  42. Define a syllable.
    A vowel-like (sonorant) sound together with the surrounding consonants most closely associated with it. E.g. dog = 1 syllable; catnip = [k ae t] + [n ih p].
  43. Define nucleus, onset, and coda.
    Nucleus: the vowel at the core of a syllable. Onset: initial consonants (if any). Coda: optional consonant(s) following the nucleus.
  44. What is a complex onset?
    An onset with more than one consonant, e.g. strike [s t r ay k].
  45. What is the rime (rhyme)?
    The nucleus plus the coda.
  46. Give the syllable structure of ham, green, eggs.
    ham: onset [h], nucleus [ae], coda [m].
    green: onset [g r], nucleus [iy], coda [n].
    eggs: no onset; nucleus [eh], coda [g z].
  47. What is syllabification?
    The task of automatically breaking a word into syllables.
  48. What is phonotactics? Example?
    Constraints on which phones can follow each other in a language. E.g. [zdr] cannot be an English syllable onset. Can be modeled with a language model or finite-state model of phone sequences.

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