1. Phonatory System Lecture 8

2. The Larynx (Anatomy Review)
Bone
Cartilage
Ligament
Membrane
Muscle

3. The Larynx Innervation Extrinsic muscles Intrinsic muscles
How the vocal folds vibrate
Initiating vibration
Pitch
Registers

4. Innervation Vagus (CN X) Superior laryngeal nerve:
Cricothyroid (CT)
Recurrent laryngeal nerve:
Thyroarytenoid (TA)
Posterior Cricoarytenoid (PCA)
Lateral Cricoarytenoids (LCA)
Interarytenoids (IA)
Blumenfeld, H., 2002, Neuroanatomy through Clinical Cases, Sinauer, Inc.

5. Extrinsic Laryngeal Muscles
Many extrinsic laryngeal muscles
Thyrohyoid
Elevates larynx
Sternothyroid
Depresses larynx
Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 112.

6. The Larynx Innervation Extrinsic muscles Intrinsic muscles
How the vocal folds vibrate
Initiating vibration
Pitch
Registers

7. Thyroarytenoid Bulk of the vocal folds Contractions can result in:
Shortening the vocal folds
Pulling thyroid and arytenoid cartilages toward each other
Increasing the tension of the vocal folds
Isometric (contracting and not changing length)
Shorten: decreases pitch
Increase tension: increases pitch
Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 98.

8. Cricothyroid When it contracts, it helps to lengthen the vocal folds
It elevates the cricoid arch, and depresses the thyroid lamina (shortens the space between the cricoid and the thyroid)
This can help to increase pitch
Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 97.

9. TA and CT: Activation Patterns
CT active and TA passive = increase pitch
Increase length
Increase stiffness
TA active and CT passive = decrease pitch
Decrease length
Decrease stiffness
TA and CT contract simultaneously = increase pitch

10. Posterior and Lateral Cricoarytenoids
Work in opposition
PCA:
Rocks arytenoids away from midline
Opens the vocal folds
LCA:
Rocks arytenoids toward midline
Closes the vocal folds
Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 100.

11. ABduction & ADduction PCA: LCA: Rocks arytenoids away from midline
ABducts the vocal folds
LCA:
Rocks arytenoids toward midline
ADducts the vocal folds
Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 107.

12. Interarytenoids Transverse: Oblique:
Pulls arytenoids toward each other
ADducts the vocal folds
Oblique:
Tips one arytenoid (apex) toward the other (body)
Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 101.

13. The Larynx Innervation Extrinsic muscles Intrinsic muscles
How the vocal folds vibrate
Initiating vibration
Pitch
Registers

14. Vocal Fold Vibration Many theories of vocal fold vibration
Myo-elastic aerodynamic theory of vocal fold vibration
Nonuniform tissue movement: Multimass models

15. Myo-elastic aerodynamic theory
Van den Berg, 1958
Based on Bernoulli equation:
P + ½ pv2 = constant
P = pressure
p = fluid density
v = velocity
Please use this formula- I believe the formula in your book is incorrect.
This equation states that as pressure increases, velocity decreases (assuming density is constant)
Based on Titze, I.R. (2000). Principles of Voice Production.

16. Myo-elastic aerodynamic theory
Van den Berg, 1958
Based on Bernoulli equation:
P + ½ pv2 = constant
Basics of this theory:
When the vocal folds are closed, pressure builds in the subglottal region
When the pressure is high enough, it forces the vocal folds open
The vocal folds continue to open further as air rushes out
Once they reach a maximum opening, the elasticity in the vocal folds pulls them together
The cycle repeats

17. Nonuniform tissue movement: Multimass models
Other theories in between, but this is the most recent
Explains self-sustained oscillation: as the vocal folds continue to oscillate (vibrate), they are able to sustain the same velocity and width of excursion
Titze, I.R. (2000). Principles of Voice Production.

18. Nonuniform tissue movement: Multimass models
Upper and lower parts of the vocal folds do not move as one
The lower part of the vocal folds moves first, followed by the upper part
Convergent: lower further apart than upper
Divergent: upper further apart than lower
Titze, I.R. (2000). Principles of Voice Production.

19. The Larynx Innervation Extrinsic muscles Intrinsic muscles
How the vocal folds vibrate
Initiating vibration
Pitch
Registers

20. Initiating vibration
Phonation threshold pressure (PTP): smallest subglottal pressure needed to start self-sustained oscillation
For low frequency phonation, PTP is around 3-4 cm H20

21. Pitch and Registers Average pitch: Registers Women: 220 Hz
Chest (Low pitches)
Men: 130 Hz
Middle/Mixed (Middle pitches)
Head/Falsetto (High pitches)
Zemlin, pg 166.