LaeKin Burgess McCoy Chapter 8

 

                           

What is the total at rest length of the vocal folds for women? For men? Eighteen millimeters for women (diameter of a dime) 23 millimeters for men (diameter of a quarter).

What is the average length of the vibrating portion of the vocal folds?     13-15 mm

Why do we call them vocal folds instead of vocal cords? Because folds more accurately describes what they are. They are folds of tissue not bands or chords like strings of a piano.

What are the vocal folds? Small folds of tissue that are located in the anterior/posterior plane at the top of the airway.

What do the vocal folds look like when viewed from above? They look like two pearly white bands in the shape of a V when open. The bottom of the V is at the front of your body.   The ventricular or false VF lie just above the true VFs.

What is the thin layer of skin cells on the VFs called? What do these 3 terms mean? Stratified Squamous Epithelium. Epithilium- means skin cells.  Squamous means that the cells interlock like paving stones.  Stratified- means the cells become progressively larger toward the bottom layer.

This area has another name.  What is it and why is it called this? Mucosa, because it is constantly bathed in mucous. Mucosa covers all of the respiratory tract from lips to bottom of trachea but only becomes SSE at the vocal folds and some areas above them.

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 vocal tract aside from what was mentioned above consists of columnar epithelium (cells arranged in columns) the ones below are ciliated (hairy).

What makes up the body of the vocal folds? Muscle called thyroaritenoid, A transitional layer called the almina propria lies between the muscle and the SSE.  Lamina propria has 3 distinct regions 1. The superficial outermost layer is coupled to the epithelium through a basement membrane. This is the thinnest and has the lowest viscosity. 2. The intermediate layer is wider and more ciscous than superficial. The vocal ligament passes through this region resulting in a texture similar to gelatin with mixed strands of cotton. 3. Deep lamina propria is the densest and most viscous.

What is the transitional layer called?  Describe it.  See above and Overall it might be compared to a three layered gelatin dessert in which the superficial layer has not quite set the intermediate layer is like normal gelatin  with appetizing cotton fivers and the deep layer is like a gummy bear.

How is the structure of the vocal folds like both the back and the palm of your hand? The cover of the VFS is like the skin on the back of your hand and palm of your hand is like a shock absorbing lamina propria.

Describe the steps of a single cycle of vibration according to the Myoelastic-Aerodynamic Model.

VF’s are gently closed by laryngeal muscles

Air pressure increases beneath the closed glottis

Increasing air pressure begins to open the glottis on the underside

The glottis continues to open from bottom to top until air begins to esace

As the air begins to flow through the glottis its velocity increases and its pressure decreases(Bernoulli effect)

Elasticity of the vocal fold acts somewhat like a spring exerting a return force that begins to close the glottis; negative pressure caused by bernoulli effect supplies additional closing force.

THE GLOTTIS CLOSES AGAIN FROM BOTTOM TO TOP

As soon as the glottis is fully closed the process begins again

What is vertical phase difference?  Why is this important to vocal sound? It is the vibration of the lower edge of the VF before the upper edge. This causes mucosal wave which is like a wave traveling across a pond but it’s the vocal folds.

Are aerodynamic factors sufficient to maintain vocal fold oscillation? NOOOOOO!

Describe the steps of VF oscillation according to the one-mass model.

The glottis is gently closed by laryngeal muscles

Subglottal air pressure increases until it overcomes the muscular and tissue resistance and opens the glottis.

Reduced air pressure through the glottis and elasticity/ inertia of the VF brings the glottis back together reduction the flow of air

Because of inertia air above the glottis continues in its forward motion in spite of reduced flow through the glottis producing and AREA OF LOW PRESSURE ABOVE THE GLOTTIS

The combined forces of elastic recoil and pressure drop through the glottis and low pressure area above the glottis closes the glottis all of the way

Asymmetry of air pressure below and above the glottis allows VF oscillation to continue for as many times as needed.

Describe the improvements in understanding VF oscillation because of the 3-mass model.

Describing the VFS as three interconnected masses. The TA is larges and Lamina propria and SSE are two smaller masses. In this model the glottis opens and closes asymmetrically with vertical phase difference from bottom to top. Air pressure is also asymmetrical increasing when the glottis is in a convergent shape and decreasing when it is divergent.

What is the neurochronaxic theory?  Is it valid?

Believed by Raoul Husson French guy 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. Scientifically discredited.

Name the 5 cartilages that form the basic laryngeal framework.

Thyroid cartilage

Cricoid cartilage

Two Arytenoid Cartilages

Epiglottis 

Name and describe the membranes and ligaments found within the larynx.   

Thyrohyoid membrane- connects the hyoid bone and thyroid cartilage sealing it and preventing excess movement. 

Membrane and ligament are found in anterior space between the cricoid and thyroid (cricothyroid) same function as thyrohyoid membrane

Conus elasticus strengthens the underside of the VFs  and seals them to the airway below. 

Describe the aryepiglottic fold.  What is its alternate name? What is its function?found at the top of the larynx (also called the laryngeal collar or epilarynx is made up of muscle and tissue that encapsulates the epiglottis and arytenoids. It helps to pull the epiglottis down to cover the ariway for wallowing. It also plays an important role in vocal resonance and is a probable source of the Singer's formant. 

What is the purpose of the vocal ligament?add strength to the medial edges of the VFs and limit the extent to which they can stretch.

What is the function of the aryepiglottic and the thyroepiglottic muscles for singing? To swallow without getting junk in your airway.

What is phonation threshold pressure (PTP)?Pressure required to overcome resistance of glottal adduction.

What are the 3 principle types of vocal onset? Describe how they differ in terms of the sequence of adduction and airflow. 

Glottal onset- hard, occurs when strong adduction precedes breath energy. VFs adducted tightly and air pressure increases until it explodes through the glottis. 

Aspirate onset- breath flow starts before VFs adduct and are allowed to oscillate

Balanced onset- airflow and adduction happen at the precise same moment. clean and easy sound without hard click of glottal or h sound of aspirate. 

What is flow phonation? perfect balance of airflow and adduction

What happens if we increase breath pressure with constant adductory tension? pitch may get slightly louder and will rise in pitch and has potential to become aspirate.

What happens is you increase glottal resistance at the same time as you increase breath pressure? The VFs will oscillate at a higher amplitude causing faster vibration higher closed quotient and crisper sound.

As amplitude increases, how does this affect the glottis? What happens to help this situation?

The glottis must work harder to resist subglottic pressure. This resistance is found in the contraction of the LCA and IA and through contraction of the TA to create medial tension in the glottis. When TA contracts in antagonism with CT muscles the VFs thicken. This widens the contact area between the two folds and effectively increases the VF mass that is in oscillation. 

How do we increase vocal fold thickness, and what affect does this have on the sound?The TA contracts and sound gets louder and timbre changes.

What is the typical dynamic range for dramatic voices?  What was maximum amplitude for these singers?60-64 dB, 120 dB

How does the dynamic range and maximum amplitude of lighter voiced singers compare? Similar range, lower maximum amplitude.

How do pitch and amplitude relate to each other? doubling F0 raises amplitude 6 dB

How is the time that the glottis remains open impacted by adduction and pressure changes? As pressure and adduction increase open quotient goes down.

What is the estimated times of the various phases in q quiet tone vs a louder tone? in a quiet tone 50% open, 37% closing, 13% closed. In a loud tone 33% Open, 37% closing, 30% closed.

What is the open quotient? Th amount of time the VFs are open during phonation.

How does the open quotient relate to amplitude? As amplitude increases the open quotient decreases.

Why is it wrong to just blow harder to get louder? It will cause the pitch to go sharp and the tone will lose core and focus. The balance between air pressure and laryngeal tension is key.

In very general terms, what must the vocal folds do to change pitch? Get tenser and longer and thinner for high pitch. Thicker and looser for lower pitch.

How does the body/cover model affect pitch change?  On lower pitches the entire fold vibrates. As pitch ascends the VFs may thin to the point that only the cover vibrates. The cover and body start to act more independent as pitch ascends.

How do pitch and intensity overlap in terms of vocal fold function? For pitch to ascend the VFs must get thinner but they also need to get thicker for greater intensity. 

How do the CT and TA work together to control pitch and amplitude? CT lengthens VFs during contraction or releases them to make pitch higher or lower. TA tenses or releases to make VFs tense or not tense changing amplitude and timbre.

Describe how variations in air pressure have different impacts on low vs. high frequencies. higher pitches require more air pressure. 

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? transformation of cartilage to bone. 

What is the downside of the flexibility of the thyroid cartilage in young people. They get used to changing pitch by constricting their inferior pharyngeal constrictors. As the thyroid cartilage ossifies that approach doesn't work anymore and you have a whole lot of squeeziness in the voice. 

Describe the actions of swallowing.  The larynx ascends to assist the epiglottis in covering the airway, soft palate is lifted closing off the nasal port, tongue elevates and retracts, walls of pharynx constrict. 

Describe the pharyngeal constrictor muscles. Superior wraps around the top of the vocal tract in the region of the nasopharynx,  attachin to the skull and mandible. 
Middle constrictor- attaches to hyoid bone and stylohyoid ligament. Runs from the hyoid to the tryloid process of the skull. 
Inferior- lies at the bottom of this muscle complex attatching to the thyroid laminae as well as the cricoid cartilage. 

What does gola aperta mean? Open throat

How do we open the throat? Release all the constrictors

What are the two ways in which laryngeal elevation can occur? Thyrohyoid and inferior pharyngeal constrictors.

Which structures is the hyoid connected to? Larnyx, tongue, jaw

Besides the inferior pharyngeal constrictor, what is the other true laryngeal elevator? Describe its function. Thyrohyoid which connects thyroid cartilage to hyoid bone closing the gap between the two and elevating the larynx. 

Which muscles are indirect laryngeal elevators? digastric, stylohyoid, mylohyoid, geniohyoid, genioglossus and hyoglossus

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? digastrics, mylohyoid and stylohyoid. 

Which muscles are laryngeal depressors? Sternothyroid, sternohyoid,  omohyoid

What is the ideal laryngeal position for classical singing? at or just below its normal resting place. 

How does the vertical position of the larynx change as we age? Be specific. Larynx gradually descends throughout life. at berth the base of cricoid is lacated at the level of the third cervical vertabrae. by age 5 it has descended to C5  and by puberty and into adulthood C7

What is tracheal pull (tug)? The diaphragm descends pulling on the lungs, paracardium, trachea, and larynx lowering the larynx with good breath gesture. 

Which nerves serve the larynx? internal and external branches of the vagus nerve the superior laryngeal nerve and the recurrent laryngeal nerve.