Phonatory System Physiology: Glottal cycles

What are the two stages to glottal cycles?

Stage 1: prephonation
Stage 2: Phonation

Stage 1: Prephonation

- As exhalation phase is about to begin: vfs adducted by adductors

- glottis "closed" or close to it

what phases does Stage 2: Phonation of the glottal cycle have?

1. closed
2. opening
3. closing
4. closed

Stage 2 phonation: 1. closed

-Vfs adducted
-Glottis closed
-Exhaled air flow blocked
-Alveolar pressure increased (also called tracheal pressure)

Stage 2 phonation: 2. opening

-Alveolar pressure increase enough to force vfs apart
-Glottis opens
- From bottom to top (like a wave)
- exhaled airflow resumes

Stage 2 phonation: 3. Closing

- Airflow continues
- Alveolar pressure decreases
- Allowing vfs rebound (vocal folds are supposed to adducted)
- Glottis narrows
- From bottom to top
- Vertical phase difference

Stage 2 phonation: 4 Closed

Glottis closes
Then
Cycle begins again

One complete glottal cycle...

describes one vf vibration

What does the glottal cycle achieve?

converts constant pressure of free airflow to alternating air pressure

What does alternating air pressure mean?

-Compression

-Rarefaction

-Result: sound wave

-An acoustic event

-Recognized as: phonation

in sum....

repeated glottal cycles result in phonation, consisting of sound wave = an acoustic event

important note:

throughout the 4 phases of glottal cycle, adductor muscles continually apply medial pressure for compression

--- > And muscles of exhalation continually maintain same alveolar pressure

What does medial compression refer to?

Muscular force with which vfs are adducted or "pressed" together at midline by adductor muscles