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Phonation +
Vocal Fold Physiology
Feburary 6, 2013
Average Everydayness
• Production exercise comments and grades were e-mailed
shortly before class;
• I’m sending the second one out tonight.
• Will be due next Wednesday…
• Today:
• The Wonderful World of the Larynx!
• But first: a completely random linguistic detour...
The Kiki/Bouba Experiment
• Originally devised by psychologist Wolfgang Köhler in 1927.
• Updated and replicated in 2001.
• Look at these two figures:
• Which one is bouba and which one is kiki?
• ~95% of both English and Tamil speakers thought the shape
on the left was “kiki”, the one the right “bouba”
Where Were We?
• Air squeezed out of
the lungs travels up
the bronchi...
• Through the trachea
(windpipe)
• To a complicated
structure called the
larynx.
• ...where phonation
happens.
The Larynx
• The larynx is a complex structure consisting of
muscles, ligaments and three primary cartilages.
1. The Cricoid Cartilage
• The cricoid cartilage sits on top of the trachea
• from Greek krikos “ring”
• It has
“facets” which
connect it to
the thyroid
and arytenoid
cartilages.
cricoid
cartilage
2. The Thyroid Cartilage
• The thyroid cartilage sits on top of the cricoid cartilage.
• from the Greek thyreos “shield”
• The thyroid cartilage has horns!
• Both lower (inferior) and upper (superior) horns
• The lower horns connect with the cricoid cartilage at the
cricoid’s lower facet.
• The upper horns connect to the hyoid bone.
Thyroid Graphic
thyroid
cartilage
cricoid
cartilage
Thyroid Angles
• The two broad, flat front plates of the thyroid--the
laminae--meet at the thyroid angle.
• The actual angle of the thyroid angle is more obtuse in
women.
• ...so the “Adam’s Apple” juts out more in men.
3. The Arytenoid Cartilages
• There are two arytenoid cartilages.
• from Greek arytaina, “ladle”
• They are small and pointy, and sit on top of the back
side, or lamina, of the cricoid cartilage.
arytenoid
cartilages
cricoid
cartilage
The Vocal Folds
• These three cartilages are connected by a variety of
muscles and ligaments.
• The most important of these are the vocal folds.
• They live at the very top of the trachea, in between
the cricoid and thyroid cartilages.
• The vocal folds are a combination of:
• The vocalis muscle
• The vocal ligament
• The vocal folds are enclosed in a membrane called the
conus elasticus.
Vocal Fold View #1
• Just above
the true vocal
folds are the
“false” (!)
vocal folds,
or ventricular
folds.
• The space
between the
vocal folds is
the glottis.
Vocal Fold View #2
• The vocal ligaments
attach in the front to
the thyroid cartilage.
• ...and in the back to
the arytenoid
cartilages.
• The glottis consists
of:
• the ligamental
glottis
• the cartilaginous
glottis
Things Start to Happen
• Note that the arytenoid cartilages can be moved with
respect to the cricoid cartilage in two ways.
#1: rocking
#2: sliding
The Upshot
• The arytenoids can thus be brought together towards
the midline of the body.
• Or brought forwards, towards the front of the thyroid.
• The rocking motion thus abducts or adducts the glottis.
• The sliding motion shortens or lengthens the vocal folds.
• Check out the arytenoids in action.
• When the vocal folds are abducted:
• air passes through the glottis unimpeded and
voicelessness results.
• The posterior cricoarytenoid muscles are primarily
responsible for separating the arytenoid cartilages.
• Voicing may occur when the vocal folds are adducted
and air is flowing up through the trachea from the lungs.
• Two muscles are primarily responsible for adducting the
vocal folds.
• The first is the lateral crico-arytenoid muscle.
• Note that the lateral cricoarytenoid muscles only
adduct the ligamental glottis.
• The transverse arytenoid muscles pull together the
arytenoid cartilages themselves.
• Thereby closing the cartilaginous glottis.
The Consequences
• The combined forces drawing the vocal folds towards
each other produce adductive tension in the glottis.
• Adductive tension is increased by:
• lateral cricoarytenoid muscles
• transverse arytenoid muscles
• Adductive tension is decreased by:
• posterior cricoarytenoid muscles
• Adduction vs. abduction determines whether or not
voicing will occur.
• But we can do more than just adduce or abduce the
vocal folds...
Controlling F0
• Question: why do women have a higher F0 than men?
• A: Shorter vocal folds open and close more quickly.
• In men:
• Ligamental glottis  15.5 mm
• Cartilaginous glottis  7.5 mm
• Total glottis length  23 mm
• In women:
• Ligamental glottis  11.5 mm
• Cartilaginous glottis  5.5 mm
• Total glottis length  17 mm
Factor Two
• F0 also depends on the
longitudinal tension in the
vocal folds.
• I.e., tension along their
length, between the thyroid
and arytenoid cartilages.
• Higher tension = higher F0
• Lower tension = lower F0
• Q: How can we change longitudinal tension in the larynx?
• A: We can rotate the thyroid cartilage up and down on its
connection with the cricoid cartilage.
• ...like the visor of a knight’s helmet.
• This either stretches or relaxes the vocal folds.
Contradictory?
• No, just complicated. Note:
• Lengthening (stretching) the folds results in higher
tension
• ...which results in higher F0
• Shortening the folds results in less tension
• ...which results in lower F0
• “Higher” and “lower” F0 have to be understood relative to
the speaker’s normal F0 range.
• still lower for men
• still higher for women
For the Record
• Contraction of the cricothyroid muscle pulls down the
thyroid cartilage.
• Interestingly:
researchers often
study the activity of
this muscle using
EMG.
Fun Stuff (= tracheotomy)
Peter Ladefoged: “To record the pressure of the air
associated with stressed as opposed to unstressed syllables
we need to record the pressure below the vocal folds. A true
recording of the subglottal pressure can be made only by
making a tracheal puncture.This is a procedure that must be
performed by a physician. A local anesthetic is applied both
externally and inside the trachea by means of a fine needle.
A larger needle with an internal diameter of 2 mm can then
be inserted between the rings of the trachea as shown in
figure 3.3”
Figure 3.3
“As you can see from my face it is not at all painful. But
it is not a procedure that can be carried out in fieldwork
situations.”
For the Record, part 2
• Longitudinal tension can also be reduced by the
thyroarytenoid muscles.
• Which connect the thyroid to the arytenoid cartilages.
• These
muscles are
inaccessible
to EMG
vocal folds
Check it out!
• Let’s look at some pitch shifting laryngoscopy videos.