1. Hillenbrand: Phonation
Note: Audio demos made with fsyn: original pitch, monotone, and inverted pitch. FDR demo original pitch and monotone only.
Hillenbrand: Phonation

2. Information Conveyed by the Source
For voiced speech, the spectrum of the laryngeal buzz constitutes the source part of source-filter theory. A great deal of the burden of phonetic coding is carried by the filter (e.g., [b]-[d]-[g]; [s]-[ʃ]; [ɑ]-[i]-[u]-[ʌ]-[ɚ], etc.) But, a good deal of speech information is conveyed by the source. For example:
1. Intonation (melodic) contour: Pattern of f0 over time conveys information about the grammatical structure of the utterance (e.g., phrase boundaries and sentence type), as well as affective information.
2. Rhythmic pattern: Pattern of stressed and unstressed syllables can convey lexical information (OBject vs. obJECT) and emphatic stress (e.g., given vs. new).
3. Loudness: Controlled mostly at the source (but filter has some effect on loudness as well).
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3. Hillenbrand: Phonation
4. Voice quality:
Clear or “modal” phonation
Whisper
Breathiness (buzz and hiss combined)
Roughness
Hoarseness
Diplophonia (two simultaneous f0s/pitches)
Pressed or strained voice
Glottal fry
Falsetto
You name it: many other hard-to-classify, hard to characterize variations in vocal quality
5. Some segmental phonetic information:
Example: Timing of voicing onset relative to articulatory release is a major cue to the voice-voiceless distinction (more later)
Hillenbrand: Phonation

4. Hillenbrand: Phonation
(Minifie et al., 1973)
Hillenbrand: Phonation

5. Hillenbrand: Phonation
Cricoid lamina is in back
Cricoid arch is in front
(Minifie et al., 1973)
Hillenbrand: Phonation

6. Hillenbrand: Phonation
(Minifie et al., 1973)
< View from the top
Hillenbrand: Phonation

7. Hillenbrand: Phonation
(Minifie et al., 1973)
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8. Hillenbrand: Phonation
(Minifie et al., 1973)
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10. Hillenbrand: Phonation
Notice that the arytenoids are angled inward; i.e., “pigeon toed”. This is not shown in many pictures. It’s a big deal.
(aka external TA)
(aka internal TA)
(Note: TA = thyroarytenoid)
Hillenbrand: Phonation

11. Hillenbrand: Phonation
The ‘pigeon toed’ angle means that the VFs will be: (a) pulled away from midline when the arytenoids rock backward, and (b) pulled toward midline when the arytenoids rock forward .
It’s not possible to understand the role of the intrinsic laryngeal muscles without appreciating the consequences of the “toe in” angle.
Hillenbrand: Phonation

12. Hillenbrand: Phonation
This is unfortunate because many pictures of the larynx do not show this feature accurately.
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13. Hillenbrand: Phonation
Mott, F.W. The Brain and the Voice in Speech and Song. Free e-book, Project Guttenberg.
One more picture: The artist is trying to show that the vocal folds move away from midline when the arytenoids rock backward, and toward midline when the arytenoids rock forward. (We’ll return to this idea later.)
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14. Hillenbrand: Phonation
Cricothyroid Joint
Note that when the cricoid moves up (i.e., closing the gap between the cricoid and the thyroid in front), the arytenoids are rotated away from the thyroid angle. We will see that this has a lot to do with the control of fundamental frequency.
Figure from David Broad (in Minifie et al., 1973, Normal Aspects of Speech, Hearing & Language)
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15. Hillenbrand: Phonation
Figure from David Broad (in Minifie et al., 1973, Normal Aspects of Speech, Hearing & Language)
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16. Figure from David Broad (in Minifie et al
Figure from David Broad (in Minifie et al., 1973, Normal Aspects of Speech, Hearing & Language)
Thyroid Notch This Way->
Rocking Motion of Arytenoids
Rocking forward (toward thyroid angle) brings VFs forward (obviously) and (less obviously) toward midline. Rocking backward (away from thyroid angle) brings VFs backward (obviously) and (less obviously) away from midline.
Hillenbrand: Phonation

17. Hillenbrand: Phonation
(Minifie et al., 1973)
Hillenbrand: Phonation

18. Hillenbrand: Phonation
(Minifie et al., 1973)
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19. Hillenbrand: Phonation
Five Layers of VFs:
1. Epithelium (very thin, very flexible)
2. Superficial layer of LP (thin, gelatinous, very flexible)
3. Intermediate layer of LP (rubbery, less flexible)
4. Deep layer of LP (like thick thread)
5. Vocalis muscle
“Cover-Body” Organization of VFs:
Cover= Epithelium + Superficial LP
Transition= Intermediate &Deep Layers of LP
Body = Vocalis muscle
It is the cover which is most heavily involved in VF
vibration – both the side-to-side motion that we all know about, but also the up and down motion that you may be less familiar with.
(Minifie et al., 1973)
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21. Hillenbrand: Phonation
Sequence of events in phonation, beginning with:
· Steady lung pressure
· Steady flow thru VFs
· Abducted VFs (i.e., away from midline)
1. A steady (DC) muscular force is applied to adduct the folds; i.e., to bring the VFs toward midline.
· A ↓
· Vo ↓ (volume velocity; i.e., air flow)
· V ­↑­ (particle velocity)
2. Bernoulli force increases: The Bernoulli Principle states that an increase in particle velocity is accompanied by an aerodynamic force that is exerted at right angles to the angle of flow.
FB®­ ¬ FB
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22. Hillenbrand: Phonation
The other way to think about FB is to think of it as a drop in pressure or sucking force inside the glottal aperture. Either way, the result is a force that bring the VFs toward midline.
3. Muscular force and Bernoulli force combine to bring the VFs to midline, where they meet.
· A = Zero (Glottal Area)
· Vo = Zero (Volume Velocity; i.e., airflow)
· V = Zero (Particle Velocity)
· FM = Steady (Muscular force)
· FB = Zero (Bernoulli force)
· Psg = Very rapid and dramatic increase (Subglottal pressure)
4. When folds meet at midline, there are two opposing forces acting:
· the muscular force acts to keep the VFs approximated
· Psg acts to blow the VFs apart and upward
At some point, Psg will reach a high enough value to win the contest, and:
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23. Hillenbrand: Phonation
5. VFs are blown apart (and up), moving away from midline
A ↑ (glottal area)
Vo ­↑ (volume velocity; i.e., air flow)
V ↓ (particle velocity)
6. The mvt of the VFs away from midline is opposed by:
· The DC muscular force (which is still in effect)
· The elasticity of the VF tissue
The VFs will move toward midline again, and the process is repeated, from step 1.
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24. Hillenbrand: Phonation
Vibratory Motion of the Vocal Folds . Note the “Vertical Phase Difference”; i.e., the VFs open bottom edge 1st, followed by top edge; close bottom edge 1st, followed by top edge.
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25. Hillenbrand: Phonation
Note that when the VFs separate, they do not just move side-to-side. The folds – especially the top edge – are also displaced upward quite a bit. This is not surprising given the upward direction of the aerodynamic force that causes them to separate in the first place.
Hillenbrand: Phonation

26. THE TWO-MASS MODEL OF PHONATION
These little dealies represent the viscosity of the vocal fold tissue. We’ll ignore that and focus on the spring-mass system.
Note that the two masses of the vocal folds are represented by a spring and mass system. What factors will control the vibrating frequency of this system?
Hillenbrand: Phonation

27. Note that VFs open bottom edge followed by top edge,
ANOTHER VIEW OF THE
TWO-MASS MODEL
Note that VFs open bottom edge followed by top edge,
and close bottom edge followed by top edge.
Light gray = top edge
Dark = bottom edge
View from above->
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28. Control of F0 in the Two-Mass Model
Fundamental Frequency Can be Increased by:
1. Increasing Stiffness: This is done by increasing the longitudinal tension of the VFs, exactly like stretching a rubber band. The stiffness increase results in an increase in natural vibrating frequency.
2. Decreasing the Effective Mass of the VFs: When the VFs are stretched, a smaller portion of the folds vibrates. This is equivalent to decreasing the mass of the VFs. The decrease in mass results in an increase in natural vibrating frequency.
MORAL: Longitudinal Tension ­↑ f0­­­­ ↑
Longitudinal Tension ↓ f0 ↓

29. INTRINSIC LARYNGEAL MUSCLES
AND THE CONTROL OF F0
Four paired muscles (i.e., one on left, one on right), one unpaired muscle.
Paired:
1. Lateral Cricoarytenoid (LCA)
- Adductor (Closer)
2. Posterior Cricoarytenoid (PCA)
- Abductor (Opener)
3. Cricothyroid (CT)
- Longitudinal tension increaser/decreaser
4. Thyroarytenoid (TA) [Internal (vocalis) / External]
- Function depends on behavior of other muscles
Unpaired:
Interarytenoid (IA) [Transverse & Oblique]
- Adductor
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30. LATERAL CRICOARYTENOID (LCA)
This muscle pulls downward and forward on the arytenoids. Contraction has the effect of rocking the arytenoids forward. Given the “toe in” angle of the arytenoids, this forward rocking motion adducts (closes) the VFs (and may increase medial compression; i.e., squeezing force).
The LCA may also reduce the longitudinal tension on the VFs. (Note: Only the right LCA is shown in this picture.)
(Minifie et al., 1973)
Hillenbrand: Phonation

31. Posterior Cricoarytenoid (PCA)
This muscle pulls back on the arytenoids. This has the effect of rocking the arytenoids backward. Given the “toe in” angle of the arytenoids, this backward rocking motion abducts (opens) the VFs.
The PCA may also increase the longitudinal tension on the VFs.
(Minifie et al., 1973)
View from the Back
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32. Cricothyroid Muscle (CT)
This muscle pulls the cricoid up, reducing the distance between the cricoid and the thyroid. Most Important: This movement rotates the cricoid lamina back and away from the thyroid notch. This pulls the arytenoids away from the thyroid notch, increasing the longitudinal tension on the VFs.
(Minifie et al., 1973)
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33. Hillenbrand: Phonation
Main Point: The CT increases the longitudinal tension of the VFs, decreasing effective mass, and increasing f0.
Figure from David Broad (in Minifie et al., 1973, Normal Aspects of Speech, Hearing & Language)
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34. Hillenbrand: Phonation
Thyroarytenoid Muscle (TA)
Note internal and external parts of TA.
Internal TA also called vocalis muscle.
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35. Hillenbrand: Phonation
Interarytenoids (IA)
Note transverse (side-to-side) and oblique parts of IA.
Contraction of IA (transverse and oblique) produces gliding motion of arytenoids; result is adduction and medial compression (squeezing).
Contraction of oblique IA may also cause apices of arytenoids to approximate.
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37. Relationship Between Glottal Area and
Glottal Volume Velocity (Air Flow)
When area is large, flow is high. No big surprise:
When a faucet is full on, flow is high.
The flow waveform is a steeper than the area
waveform. (Flow is proportional to Area3; e.g., if
area is doubled, flow increases by a factor of 23= 8.)
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38. Time Organization/Frequency Organization
There is a close and predictable relationship between the shape of the glottal pulse and the spectrum of that pulse.
When the slope of the glottal wave is steep (more like an impulse), there will be a lot of energy spread into the higher frequency harmonics.
When the slope of the glottal wave is gradual (more like a sinusoid), there will be less energy spread into the higher frequency harmonics.
Hillenbrand: Phonation

39. Time Organization/Frequency Organization
This figures shows just two extremes:
A nearly impulse-like waveshape (high time organization – events are “compressed” in time) with lots of energy spread to the upper harmonics (low frequency organization).
A nearly sinusoidal waveshape (low time organization – events are spread evenly over time) with nearly all of the energy at the fundamental frequency (high frequency organization).

40. Time Organization/Frequency Organization
Note that more impulsive-looking waveforms produce more energy spread into the higher frequencies. The more smooth and sinusoidal-looking waveforms have a greater amount of their energy concentrated at the 1st harmonic (f0), and less energy in higher frequency harmonics.
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41. Abrupt Glottal Closure
Effects of Gradual vs.
Abrupt Glottal Closure
Gradual closure, energy concentrated strongly at f0.
More abrupt closure, more energy spread to harmonics above f0.
The glottal waveforms above differ only in the abruptness of glottal closure. Notice that the glottal waveform with more gradual closure is fairly weak in higher frequency harmonics. Conversely, the glottal waveform showing more abrupt closure shows stronger upper harmonics. Rapid glottal closure is accomplished mainly by the lightest and most flexible portion of the VFs – the VF cover (epithelium & super- ficial layer of the LP).

42. Hillenbrand: Phonation
MORAL: Time organization and frequency organization are inversely related.
When time organization is high (like an impulse), frequency organization is low (energy is spread or “splatters” into the higher frequencies).
Conversely, when time organization is low (like a sinusoid), frequency organization is high (energy is concentrated near a single frequency).
So:
Transient-looking waveforms have a lot of energy spread into the higher frequencies.
Sinusoidal-looking waveforms have most of their energy near the fundamental.
Hillenbrand: Phonation