Monday, March 17, 2014

Jared Daley McCoy chapter 8

What is the total at rest length of the vocal folds for women? 
- about 18 millimeters, or the diameter of a dime For men? about 23 millimeters, or the diameter of a quarter

What is the average length of the vibrating portion of the vocal folds? 
- 12-15 millimeters

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? 
-two pearly white bands that form the letter V

What is the thin layer of skin cells on the VFs called? 
-What do these 3 terms mean?stratified (layered with the bigger cells on bottom) squamous (interlocking like paving stones) epithelium (layers of skin cells)

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?
- the thyroarytenoid muscle

What is the transitional layer called? Describe it. 
-the lamina propria, which is made up of three layers: superficial lamina propria, which is thinnest and lowest viscosity; intermediate lamina propria, which is wider and more viscous, and contains the vocal ligament; and the deep lamina propria, which is the thickest, 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-VFs gently closed by muscle, 2-air pressure increases below glottis, 3-air pressure begins to open glottis from the bottom, 4-glottis continues to open, bottom to top, 5-air flow escapes through glottis, increasing velocity and decreasing pressure, 6-VF elasticity acts as spring to help close glottis, negative air pressure helps close glottis too, 7-glottis closes, bottom to top, 8-process begins again

What is vertical phase difference? Why is this important to vocal sound?
- the lower edge of the VF precedes the upper edge in opening and closing--this helps in the creation of a mucosal wave

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-glottis closed by muscle, 2-subglottal air pressure increases to overcome resistance and opens glottis, 3-reduced air pressure and elasticity of VFs bring glottis back together, reducing air flow, 4-an area of low pressure above the glottis is created, 5-the elastic recoil, pressure drop through and above glottis closes glottis, 6-asymmetry of air pressure continues VF oscillation

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?
- the VFs vibrate solely as a result of nerve impulses from the brain and that airflow is only responsible for conveying sound--this isn't a valid theory

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? What is its function?
 -made of muscle and tissue that encapsulates epiglottis and arytenoids, epilarynx, helps to pull epiglottis down to cover airway

What is the purpose of the vocal ligament?
- to add strength to the medial edges of the VFs and limit stretching

What is the function of the aryepiglottic and the thyroepiglottic muscles for singing?
- none--just for swallowing

What is phonation threshold pressure (PTP)?
- pressure required to overcome 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--strong VF adduction preceding breath energy, aspirate--breath flow then VF adduction, balanced--VF adduction and breath flow happening simultaneously

What is flow phonation?
- balanced airflow and VF adduction

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? 60-64dB, 120dB

How does the dynamic range and maximum amplitude of lighter voiced singers compare?
-similar range, but with lower max. amplitude

How do pitch and amplitude relate to each other?
- doubling fundamental frequency increases 6dB

How is the time that the glottis remains open impacted by adduction and pressure changes?
- as adduction and pressure increase, time glottis is open is shorter

What is the estimated times of the various phases in q quiet tone vs a louder tone?
- 50% open, 37% closing, 13% closed in quiet phonation; 33% open, 37% closing, and 30% closed in louder phonation

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.
- connects to thyroid cartilage, wraps around vocal tract, contracts for swallowing, narrowing pharynx and elevating larynx

What is ossification?
- 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 larynx
- ascends to help epiglottis fold over airway and to direct food into esophagus, soft palate is lifted to close off nasal port, tongue elevates and retracts, pharynx constricts

Describe the pharyngeal constrictor muscles.
- superior--wraps around top of vocal tract and attaches to skull and mandible to narrow pharynx, middle--attaches to hyoid and stylohyoid ligament to narrow pharynx, inferior--attaches to thyroid laminae and cricoid cartilage to constrict pharynx and lift larynx

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?
- jaw is lowered, but larynx is still elevated

Which muscles can both depress the jaw and raise the larynx?
- anterior belly of the digastric

Which muscles are laryngeal depressors? 
-sternothyroid

What is the ideal laryngeal position for classical singing?
- at the natural resting position of the larynx

How does the vertical position of the larynx change as we age?
- Be specific. at birth, base of cricoid at C3; at age 5, at C5; at puberty and into adulthood--C7

What is tracheal pull (tug)?
- the natural lowering of the larynx upon inhalation--the diaphragm descends, pulling with it the lungs, trachea, and larynx

Which nerves serve the larynx?
 vagus nerve

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