the phonatory system part 2

the vocal folds: cover body model

a theory that wee use to explain the vibratory characteristics of the vocal folds

cover of the vocal folds

flexible epithelium and superficial layer of the lamina propria (most flexible/compliant layer)

vocal ligament

intermediate and deep lamina propria; less compliant than the cover but more compliant than the body

body of the vocal folds

made up of the thyroarytenoid (vocalis) muscle

glottis

space between the vocal folds

membranous glottis

anterior three-fifths of the glottis; bounded by vocal ligament

cartilaginous glottis

posterior 2/5 of the glottis; bounded by cartilage

glottis during quiet breathing

somewhat open (vocal folds are abducted)

glottis during forced inspiration

widely open (vocal folds are abducted)

glottis during phonation of a voiced sound

closed with vocal folds in median position (vocal folds are adducted)

glottis during whispering

closed along most of its length but with a small posterior opening

frequency

how many cycles per second that the vocal cords are vibrating

higher frequency

more vibrations

lower frequency

less vibrations

average fundamental frequency for adult men

about 130-140 Hz

average fundamental frequency for adult women

about 180 Hz

myoeslastic-aerodynamic theory of phonation

muscles adduct the vocal folds and the air passing through is what makes them vibrate; as exhalation is occurring, the vocal folds are adducted, air pressure builds up underneath the vocal folds, when air pressure is sufficient, a little puff of air bursts through the adducted vocal folds, travels into the vocal folds, at the same time the vocal folds are already coming back together at the bottom due to the medial pressure of the muscles and the Bernoulli principle, the vocal folds are sucked back together and burst apart again

bernouili principle

states that a gas (such as air) passing through a narrow channel increases in velocity and decreases in pressure; this decrease in air pressure can cause resting bodies to be sucked together

what are hiccups?

uncontrolled spasms of the diaphragm, which causes your lungs to suddenly fill with air, also because of the negative pressure, vocal folds are sucked together, which causes the sound