Phonation + Voice Quality

1. Phonation + Voice Quality Feburary 11, 2014

2. Weekday Update • Course project report #2 is due right now! • I have guidelines for course project report #3, too. • I’ve graded the DSP exercise… • Let’s have a little chat about it. • I still need to grade the production exercise… • And will be sending out a second one thereafter. • Most likely due after the break. • Today: • The larynx and voice quality. • Let’s check out some larynx models!

3. Heretofore • We have talked two different factors affecting phonation in the larynx: • Adductive Tension • Tension towards center of glottis • Pushes vocal folds towards each other • Controls voicing (and voicelessness) • Longitudinal Tension • Tension along the length of the vocal folds • Increases or decreases F0

4. Phurther Phonation Phacts • 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

5. 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

6. “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

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

8. 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.

9. 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.

10. 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

11. 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: • tends to work better on men than women.

12. EGG Readout

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

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

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

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

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

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

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

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

21. 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?

22. Factor #3 • 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.

23. 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

24. 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

25. 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…

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

27. 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

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

29. 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 • Check out the tense voice video.

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

31. 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.