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Voice Quality

Voice Quality. February 12, 2009. A Framework Rehash. Last time, we found out that the larynx is built upon a framework of three different cartilages: The thyroid cartilage The cricoid cartilage The arytenoid cartilage(s). A Movement Rehash.

mary-figueroa
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Voice Quality

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  1. Voice Quality February 12, 2009

  2. A Framework Rehash • Last time, we found out that the larynx is built upon a framework of three different cartilages: • The thyroid cartilage • The cricoid cartilage • The arytenoid cartilage(s)

  3. A Movement Rehash • The cartilages are held together by a network of muscles and ligaments. • The contraction of specific muscles can move the cartilages around with respect to each other. • The arytenoid cartilages can exhibit two movements: • “Rocking” towards each other • Either abducts or adducts the vocal folds • “Sliding” towards the thyroid • The “rocking” motion induces adductive tension in the vocal folds.

  4. We can also rotate the thyroid cartilage up and down on its connection with the cricoid cartilage. • ...like the visor of a knight’s helmet. • This either stretches or relaxes the vocal folds.

  5. Two Factors • F0 depends on the length of the vocal folds. • (longer in men than in women) • F0 also depends on the longitudinal tension in the vocal folds. • I.e., tension along their length, between the thyroid and arytenoid cartilages. • Higher tension = higher F0 • Lower tension = lower F0

  6. Contradictory? • No, just complicated. Note: • Lengthening (stretching) the folds results in higher tension • ...which results in higher F0 • Shortening the folds results in less tension • ...which results in lower F0 • “Higher” and “lower” F0 have to be understood relative to the speaker’s normal F0 range. • still lower for men • still higher for women

  7. For the Record • Contraction of the cricothyroid muscle pulls down the thyroid cartilage. • Interestingly: researchers often study the activity of this muscle using EMG.

  8. For the Record, part 2 • Longitudinal tension can also be reduced by the thyroarytenoid muscles. • Which connect the thyroid to the arytenoid cartilages. • These muscles are inaccessible to EMG vocal folds

  9. Factor #3 • Increasing longitudinal tension also makes the vocal folds thinner. • Thinner vocal folds open and close more quickly. low F0 mid F0 high F0 • Average thickness of male vocal folds = • 2-5 mm • Female folds are somewhat thinner

  10. Frequency and Vowels • In the mystery tone language exercise, you may have noticed that the fundamental frequency of [i] was slightly higher than that of [a], for the same tones

  11. “Intrinsic” Pitch • It’s been observed that F0 is usually higher for high vowels than for low vowels • [i] 183 Hz • [e] 169 • [æ] 162 • [a] 163 • [o] 170 • [u] 182 • Data from Lehiste & Peterson (1961) for American English

  12. The “Tongue Pull” Hypothesis (Honda, 2004): • Raising the tongue for front vowels also raises the larynx • The cricoid cartilage rises up and around the spine… • Thus stretching the vocal folds • and increasing longitudinal tension.

  13. An Intrinsic Summary • High Vowels Low Vowels • Intensity Less More • Duration Shorter Longer • F0 Higher Lower • A word of caution: • All of these factors (intensity, duration, F0) factor into perceived prominence and stress.

  14. Contact! • Interesting (and important) fact: the vocal folds do not open and close all at once. • Their upper and lower parts open and close out of phase with each other.

  15. Implications • Glottal opening and closing forms a complex wave. • The out-of-phase factor is reduced with thinner vocal folds. • i.e., the glottal cycle becomes more sinusoidal

  16. Electroglottography • The degree of vocal fold separation during voicing can be measured with a method known as electroglottography (EGG) • Electrodes are placed on either side of the larynx • More contact between vocal folds  greater conductivity between electrodes • A caveat: • works better on men than women.

  17. EGG Readout

  18. EGG Output “The north wind and the sun were disputing which was the stronger, when a traveler came along wrapped in a warm cloak.”

  19. An EGG Schematic 1. Complete closure of vocal folds conductivity

  20. An EGG Schematic 2. Lower half of folds begin to open conductivity

  21. An EGG Schematic 3. Upper half of folds open conductivity

  22. An EGG Schematic 4. Folds are completely apart conductivity

  23. An EGG Schematic 5. Lower half of folds begin to close conductivity

  24. An EGG Schematic 6. Upper half of folds close conductivity

  25. An EGG Schematic 7. Folds are completely closed, again conductivity

  26. An Actual EGG Waveform • Modal voicing (by me): • Note: completely closed and completely open phases are both actually quite short. • Also: closure slope is greater than opening slope. • Q: Why might there be differences in slope?

  27. Factor #5 • There is another force at work: medial compression. • i.e., how tightly the folds themselves are compressed against each other. • Medial compression determines, to some extent, how quickly/slowly the folds will open.

  28. MC Forces, yo • Medial compression is caused by constriction of: • The lateral cricoarytenoids • which adduct the vocal folds • The thyroarytenoids • which pull the arytenoids towards the thyroid • But not the interarytenoids • ...which only squeeze the arytenoid cartilages together

  29. For the Record, part 3 • It is not entirely clear what the role of the vocalis muscle plays in all this. • The vocalis muscle is inside the vocal folds

  30. The Vocalis Muscle • It may also shorten the vocal folds through contraction • thereby potentially lowering longitudinal tension • and lowering F0 • However, the same contraction would increase medial compression within the vocal fold • thereby decreasing vocal fold thickness • and increasing F0 • Researchers still need to figure out a way to get at this muscle while it’s in action…

  31. Vocal Fold Force Summary • Adductive Tension • between arytenoids • Longitudinal Tension • stretches vocal folds • Medial Compression • squeezes vocal folds together

  32. 1. Modal Voice Settings • At the low end of a speaker’s F0 range: • Adductive tension force is moderate • Medial compression force is moderate • Vocal folds are short and thick. • = longitudinal tension is low • Moderate airflow • F0 is increased by: • Increasing the longitudinal tension •  activity of the cricothyroid muscle • Increasing airflow

  33. A Different Kind of Voicing • Tuvan throat singing (khoomei):

  34. A Different Kind of Voicing • The basic voice quality in khoomei is called xorekteer. • Notice any differences in the EGG waveforms? • This voice quality requires greater medial compression of the vocal folds. • ...and also greater airflow

  35. Modal vs. Tense Voice • The language of Mpi contrasts modal voice vowels with tense voice vowels. • Mpi is spoken in northern Thailand.

  36. Taken to an Extreme • Extreme medial compression can lead to the closure of the ventricular folds, as well as that of the true vocal folds. • = ventricular voice • The false and true vocal folds effectively combine as one. • …and open and close together (usually) • Kargyraa voice • Head over to the video evidence.

  37. Ventricular Voice EGG • Notice any differences? • Difference between closing and opening slope is huge! • Also: amplitude is larger.

  38. 2. Creaky Voice • A voice quality that is somewhat similar to ventricular voice is creaky voice. • Also known as “glottal fry” • Laryngeal settings for creaky voice: • Ventricular folds often compressed down on true vocal folds. • High medial compression • Very little longitudinal tension • Low airflow •  Air bubbles up sporadically through the folds, near the thyroid arch.

  39. Creaky EGG • Note: vocal folds are very short during creaky voicing. • Look at the creaky video.

  40. Creaky Quirks • Note: creaky voice often emerges at the low end of a speaker’s range. • In a language like English, at the ends of utterances • In a tone language, for very low tones. • Note: creaky voice also often has a “double pulse” effect.

  41. Modal to Creaky [ ]

  42. Jitter • Creaky voice often exhibits a lot of jitter and shimmer. • Jitter = • Variation in timing of glottal pulses • Defined as a percentage: • period deviation/period duration.

  43. Shimmer • Shimmer = • Variation in amplitude of glottal pulses • Note: synthetic speech has to include jitter and shimmer • …otherwise the voice won’t sound natural. • Check the measures out in Praat.

  44. 3. Breathy Voice • In breathy voice, the vocal folds remain open… • and “wave” in the airflow coming up from the lungs. • Laryngeal settings for breathy voice: • Low medial compression • Minimal adductive tension • Variable longitudinal tension (for F0 control) • Higher airflow • Check out the breathy video.

  45. Breathy Voice EGG • Also note: closure phases in breathy voice are more symmetrical than in modal voice.

  46. Contrasts • Gujarati contrasts breathy voiced vowels with modal voiced vowels: • Hausa contrasts modal [j] with creaky [j]: • Hausa is spoken in West Africa (primarily in Nigeria) • Creaky consonants are also said to be laryngealized.

  47. All Three • Jalapa Mazatec has a three-way contrast between modal, breathy and creaky voiced vowels: • Jalapa Mazatec is spoken in southern Mexico, around Oaxaca and Veracruz.

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

  49. Open Quotient • From EGG measures, we can calculate the “open quotient” for any particular voicing cycle = • time glottis is open • period of voicing cycle • EGG measures show that there are reliable differences in open quotient values between the three primary voicing types. • Breathy voicing has a high open quotient • Creaky voicing has a low open quotient • Modal voicing is in between

  50. Open Quotient Traces

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