What is the total at rest length of the vocal folds for
women? For men? 18mm for women, and 23
mm for men.
What is the average length of the vibrating portion of the
vocal folds? 12-15mm
Why do we call them vocal folds instead of vocal cords? fold describes the anatomy more precisely,
they are small folds of tissue.
What are the vocal folds? Small folds of tissue located in the anterior/posterior plane at the
top of the airway.
What do the vocal folds look like when viewed from above? A “V” with the point at the anterior end.
What is the thin layer of skin cells on the VFs called? What
do these 3 terms mean? Stratified squamous epithelium. Epithelium means skin, squamous means
interlocking, and stratified means it becomes gradually bigger toward the
bottom layer.
This area has another name. What is it and why is it called this? mucosa, because it’s constantly bathed in mucus.
What is unique about this layer of skin (covering the VFs)
as opposed to the rest of the epithelium of the vocal tract? The rest of the epithelium is cells
arranged in columns, not like a squamous.
Below the folds, the epithelium is covered in microscopic hairs, for
transporting mucus.
What makes up the body of the vocal folds? muscle, TA.
What is the transitional layer called? Describe it. lamina propria, subdivides
into three distinct regions: superficial (outermost, thinnest, lowest
viscosity), intermediate (wider and more viscous, vocal ligament passes through
this region), deep (densest and most viscous)
How is the structure of the vocal folds like both the back
and the palm of your hand? The vocal
folds offer padding and shock absorption like the palm, while also having a
epithelium layer that can slide on top, like the back of the hand.
Describe the steps of a single cycle of vibration according
to the Myoelastic-Aerodynamic Model.
1. The vocal folds
are gently closed by muscular forces within the larynx
2. Air pressure
increases beneath the closed glottis
3. Increasing air
pressure begins to open the glottis.
Because of the ability of the cover to move independently of the body,
the this opening begins on the underside of the glottis
4. The glottis
continues to open, from bottom to top, until air begins to escape.
5. As the air begins
to flow through the glottis, its velocity increases and its pressure decreases,
as explained by the Bernoulli effect.
6. Elasticity of the
vocal fold acts somewhat like a spring, exerting a return force that begins to
close the glottis; negative pressure caused by the Bernoulli effect supplies
additional closing force.
7. The glottis closes
again, from bottom to top
8. As soon as the
glottis is fully closed, the process begins again, repeating as many times per
second as the frequency of the pitch being spoken or sung.
What is vertical phase difference? Why is this important to vocal sound? This means that the lower
edge of the glottis closes before the upper edge does. This is a major factor in the creation
of the mucosal wave. Why is the
mucosal wave important to vocal sound?
I don’t know.
Are aerodynamic factors sufficient to maintain vocal fold
oscillation? No, but they are sufficient
to initiate it.
Describe the steps of VF oscillation according to the
one-mass model.
1. As in the A-M
theory, the glottis initially is closed by muscles in the larynx
2. Subglottal air
pressure increases until it overcomes the muscular and tissue resistance and
opens the glottis.
3. Reduced air
pressure through the glottis (Bernoulli) and elasticity/inertia of the vocal
folds brings the glottis back together reducing the flow of air.
4. Because of
inertia, air above the glottis continues its forward motion in spite of reduced
flow through the glottis, producing an area of low pressure immediately above
the glottis
5. The combined
forces of elastic recoil of the folds, the pressure drop through the glottis,
and the low pressure region above the glottis complete the cycle, closing the
glottis.
6. Asymmetry of air
pressure below and above the glottis allows vocal fold oscillation to continue
for as many times per second as F0 of the pitch that is spoken or
sung.
Describe the improvements in understanding VF oscillation
because of the 3-mass model. The 3 mass model adds the idea that the
vocal fold is not one mass that oscillates uniformly, but one comprised of
three parts (body being the biggest, and the lamina propria and epithelium
being two smaller ones) This helps
us understand how vertical phase difference could possibly happen.
What is the neurochronaxic theory? If it valid? This
theory states that nerve impulses from the brain are the sole cause of vocal
fold vibration and that airflow only is needed to carry the sound outside the
body. This theory has been discredited.
Name the 5 cartilages that form the basic laryngeal
framework. thyroid, cricoid, 2
arytenoids, epiglottis, and trachea.
Name and describe the membranes and ligaments found within
the larynx.
thyrohyoid – links
the two structures, provding a seal and preventing excess movement
cricothyroid –
similar to above, except with different structures
conus elasticus –
inside the cricoid cartilage, strengthens the underside of the vocal folds and
seals them to the airway below.
Describe the aryepiglottic fold. What is its alternate name? laryngeal collar or epilarynx What is its function? At the top of the larynx, muscle and tissue
that encapsulates the epiglottis and arytenoids, helping to pull the epiglottis
down to cover the airway for swallowing.
Probably the source of the singers formant!
What is the purpose of the vocal ligament? To add strength to the medial edges of the
vocal folds and to limit the extent to which they can be stretched.
What is the function of the aryepiglottic and the
thyroepiglottic muscles for singing? They
tilt the epiglottis slightly backward while simultaneously narrowing the
laryngeal outlet at the epilarynx, thereby enhancing the strength of the
singer’s formant.
What is phonation threshold pressure (PTP)? The pressure required to overcome the
resistance of glottal adduction and initiate vocal fold oscillation.
What are the 3 principle types of vocal onset? Describe how
they differ in terms of the sequence of adduction and airflow.
glottal onset – glottis is squeezed tightly shut first,
then subglottal pressure forces the glottis open
aspirate onset –
breath flow starts first, and then the vocal folds are slowly adducted into the
moving air until the Bernoulli effect enables oscillation to begin.
balanced onset –
adduction and airflow begin at the same time.
What is flow phonation? perfect
union of airflow and adductory tension.
What happens if we increase breath pressure with constant
adductory tension? The sound will probably get louder, but it
also will rise in pitch and has the potential to become aspirate from excess
airflow.
What happens is
you increase glottal resistance at the same time as you increase breath pressure?
An increase in amplitude without an
increase in frequency.
As amplitude increases, how does this affect the glottis? What happens to help this situation? As
amplitude increases, the glottis must work harder and harder to resist
subglottal air pressure.
How do we increase vocal fold thickness, and what affect does
this have on the sound? Contraction of
the TA, higher amplitude.
What is the typical dynamic range for dramatic voices? What was maximum amplitude for these
singers? 60-64 db, max amp at 120 db
ish.
How does the dynamic range and maximum amplitude of lighter
voiced singers compare? The dynamic
range was similar, but the maximum amp was much lower.
How do pitch and amplitude relate to each other? As pitch rose, so did amplitude.
How is the time that the glottis remains open impacted by
adduction and pressure changes? As
adduction and pressure increase, the length of time the glottis remains open
becomes progressively shorter.
What is the estimated times of the various phases in q quiet
tone vs a louder tone?
quiet tone:
50%
opening
37%
closing
13%
closed
loud tone:
33%
opening
37%
closing
30%
closed
What is the open quotient? represents the time the glottis is open during each cycle (0 meaning
the glottis never opened, 1 meaning it never closed)
How does the open quotient relate to amplitude? Lower
the quotient, the higher the amplitude.
Why is it wrong to just blow harder to get louder? Because the proper way to increase amplitude
is to find different balances between laryngeal tension and breath pressure,
not just more breath pressure (you’ll just go sharp)
In very general terms, what must the vocal folds do to
change pitch? The vocal folds must be
elongated for pitch to ascend and shortened for pitch to descend.
How does the body/cover model affect pitch change? When the pitch is lower the whole unit
oscillates. As pitch gets higher,
the cover mostly oscillates, not the body.
How do pitch and intensity overlap in terms of vocal fold
function? In really high pitches, the
folds need to lengthen and thicken simultaneously.
How do the CT and TA work together to control pitch and
amplitude? The CT muscles pull the folds
to the appropriate tension for a given pitch while the TA muscles counter with
appropriate tension for the given amplitude.
Describe how variations in air pressure have different
impacts on low vs. high frequencies.
High pitches tend to require more
subglottal air pressure than low pitches.
Simply increasing air pressure can raise fundamental frequency! (consider
Heimlich exercise) Variations in air pressure impact lower fundamental
frequencies more strongly than higher frequencies.
Describe the inferior pharyngeal constrictor muscles
connection to the larynx. Describe its function. Attaches to either side of the thyroid cartilage and wraps around the
vocal tract and the base of the esophagus. Contraction narrows the pharynx and elevates the larynx.
What is ossification? The
gradual transformation of cartilage to bone
What is the downside of the flexibility of the thyroid
cartilage in young people. Vocal
instability and unpredictability
Describe the actions of swallowing Soft palate is lifted, closing off the nasal port so food doesn’t go up
the nose. Tongue elevates and
retracts, pushing food into the throat, while the walls of the pharynx
constrict to assist in the process.
The larynx rises sharply to assist the epiglottis in closing up.
Describe the pharyngeal constrictor muscles. The
superior constrictor wraps around the top of the vocal tract, the middle
constrictor attaches to the hyoid bone.
The inferior constrictor lies at the bottom. The upper two constrictors serve to narrow the pharynx to
swallow, and the lower constrictor lifts the larynx.
What does gola aperta mean? open throat
How do we open the throat? No muscles actually open the throat, so Maximum opening of the throat
occurs when all tension is released from the 3 constrictor muscles.
What are the two ways in which laryngeal elevation can
occur? 1. Lifted directly through an attachment to the thyroid or cricoid. 2.
Lifted indirectly through the hyoid bone.
Which structures is the hyoid connected to? larynx, tongue, and jaw.
Besides the inferior pharyngeal constrictor, what is the
other true laryngeal elevator? Describe its function. Thyrohyoid muscle, lifts the larynx and partially closes the gap
between the thyroid and the hyoid.
Which muscles are indirect laryngeal elevators? digastric (they serve to lower jaw/raise
larynx), stylohyoid, mylohyoid, geniohyoid, hyoglossus, genioglossus.
If the muscles that close the jaw (masseter, temporalis, medial
pterygoid) fail to release when the jaw is opened, what if the effect of the
contraction of the anterior belly of the digastric?
Which muscles can both depress the jaw and raise the larynx?
Which muscles are laryngeal depressors? sternothyroid, sternohyoid, omohyoid
What is the ideal laryngeal position for classical singing? allowing the larynx to remain at or very
slightly below it’s natural resting place. Regardless of where, it cannot be held rigidly.
How does the vertical position of the larynx change as we
age? Be specific. At birth, the base of
the cricoid is located at the level of the third cervical vertebra. By age 5, it has already descended to
C5. Puberty induces the next big
change, lowering the larynx to C7, with some additional lowering continuing
throughout adulthood.
What is tracheal pull (tug)? Diaphragm pulls down on lungs, and in turn the trachea as well.
Which nerves serve the larynx? Vagus nerve: superior laryngeal nerve and recurrent laryngeal nerve.
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