1. Phonation
Muscle Review & Physiology

2. Key Laryngeal Cartilages

3. Thyroarytenoid/Vocalis

4. Thyroarytenoid/Vocalis Location

5. PCA & Interarytenoids

6. PCA Action

7. Interarytenoid Action

8. LCA

9. LCA Action

10. Cricothyroid

11. Cricothyroid Activity

12. Cricothyroid Location and Action

14. Laryngeal Physiology
• The vibrating vocal folds are the major source of
periodic sound for speech. The vocal folds may
also produce aperiodic sounds.
• In this section, we discuss two main aspects of
phonatory physiology:
– 1. How are the vocal folds put into vibration?
– 2. How do we change the manner in which the
vocal folds vibrate?

15. Glottal Tone Initiation
• Before sound can be produced from the
vocal folds, several conditions must be
established:
• 1. The vocal folds must be approximated or
at least brought into the phonatory position.
Phonation may also be initiated after
complete closing of the vocal folds.

16. • 2. It is also necessary to properly tense and
elongate the vocal folds prior to actually
producing sounds. Length and tension are
important determinants of the fundamental
vibrating rate of the vocal folds.

17. • 3. Finally, there must be airflow from the
lungs. In order to be able to produce the
required flow of air from the lungs, there
must be a sufficient quantity of air in the
lungs.
• Once the aforementioned conditions have
been met, phonation can start.

18. The Phonatory Cycle: The
Aerodynamic-Myoelastic
Theory
• The vocal folds are brought to the midline
of the glottis via muscular forces.
• Vocal fold adduction must occur in
coordination with the expiratory air stream.
• Subglottal air pressure builds below the
closed folds.
• The pressure eventually overcomes the
resistance of the folds and separates them.

19. The Bernoulli Force
• The vocal folds return to the midline of the glottis
due to (a) elasticity, and (b) the Bernoulli force:
– When a gas/fluid moving through a tube
reaches a constriction, its velocity increases.
– As the gas speeds through the point of
constriction, a pressure drop occurs
perpendicular to the direction of flow.
• The vocal folds are sucked back together in this
zone of low pressure.

20. Fluid Flow Through a
Constriction