Emily C., McCoy, Ch. 8

Emily C., McCoy, Ch.8

• What is the total at rest length of the vocal folds for women? For men?
• women: 18 mm, men: 23 mm
• What is the average length of the vibrating portion of the vocal folds?
• Only the back vibrates; 12-15 mm
• Why do we call them vocal folds instead of vocal cords?
• Because it’s more accurate to call them folds; they’re not longitudinal bands. 
• What are the vocal folds?
• small folds of tissue located in the anterior/posterior plan at the top of the airway.
• What do the vocal folds look like when viewed from above?
• Two pearly-white bands, looking like V at rest but come together for phonation. The base of the V points to the front of your neck. 
• What is the thin layer of skin cells on the VFs called? What do these 3 terms mean?
• Stratified squamous epithelium. (skin cells: epithelium; paving stones: squamous; layered: stratified). 
• This area has another name.  What is it and why is it called this?
• The mucosa because it is 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 columnar epithelium/cells arranged in columns covers everything else besides mucosa on VF. The lower part is ciliated with small hairs that transport mucus up for disposal. 
• What makes up the body of the vocal folds?
• The thyroarytenoids 
• What is the transitional layer called?  Describe it.
• Lamina propria; between the VF and the epithelial cover. There are three regions from changes in distribution of elastin and collagen fibers. (superficial [thinnest, lowest viscosity], intermediate [vocal ligament passes through here], deep [thickest]) 
• How is the structure of the vocal folds like both the back and the palm of your hand?
• On the top, it’s free to move, while on the bottom, it’s more set/anchored into place and is more of a shock absorber. 
• Describe the steps of a single cycle of vibration according to the Myoelastic-Aerodynamic Model.
• Oscillation of VF maintained exclusively by muscular and aerodynamic processes. 
• 1-8 steps: VF gently closed by muscular force, air pressure increases beneath closed glottis, pressure opens glottis and opening begins on underside, glottis opens from bottom to top until air escape, as air flow, velocity increases and pressure decreases (Bernoulli Effect), Elasticity closes glottis and neg. pressure from B. effect supplies more closing force, glottis closes from bottom to top, when glottis is closed again then process repeats. 
• What is vertical phase difference?  Why is this important to vocal sound?
• The slight time lag between the opening and closing of the inferior and superior portions of the VFs; It’s like a ripple/wave in water. This helps maintain VF oscillation and helps make continuous sound… I think… 
• Are aerodynamic factors sufficient to maintain vocal fold oscillation?
• They could initiate oscillation, but there’s not enough to maintain it. 
• Describe the steps of VF oscillation according to the one-mass model.
• 1-6 steps: Glottis closed by muscles in larynx, sub glottal air pressure opens glottis, reduced air pressure through glottis (Bernoulli) and elasticity/inertia of VF brings glottis back together, reducing air flow, Inertia causes air above glottis to continue and causes low pressure immediately above glottis, combined elastic recoil causes pressure drop through glottis, and low pressure region above the glottis completes the cycle and closes glottis, this allows VF oscillation to continue because of asymmetrical air pressure above/below folds. 
• Describe the improvements in understanding VF oscillation because of the 3-mass model.
• TA muscle is first/largest mass. the upper/lower portions (lamina propria and epithelium) are two smaller masses. Glottis opens/closes asymmetrically with vertical phase difference from bottom to top; air pressure is also asymmetrical (increase when bottom of folds are farther apart, decreasing when tops of folds are farther apart). 3 mass model, pressure changes above glottis caused by inertia to sustain VF oscillation. 
• What is the neurochronaxic theory?  Is it valid?
• Raoul Husson. Nerve impulses from brain are sole cause of VF vibration and airflow is only to carry the sound outside the body. No; muscles can’t vibrate that fast on their own. 
• Name the 5 cartilages that form the basic laryngeal framework.
• Hyoid bone, epiglottis, thyroid cartilage, cricoid cartilage, inferior/superior horn, arytenoid cartilages, cricoid cartilage. 
• Name and describe the membranes and ligaments found within the larynx.
• thyrohyoid membrane: between thyroid cartilage and hyoid bone; links them, pro vents excess movement. 
• Cricothyroid membrane: also prevents excess movement. Inside the cricoid cartilage is the conus elasticus, strengthens underside of VF. 
• Describe the aryepiglottic fold.  What is its alternate name? What is its function?
• top of larynx (a.k.a. laryngeal collar or epilarynx). muscle and tissue that encapsulates epiglottis and arytenoids, pulling epiglottis down for swallowing.
• What is the purpose of the vocal ligament?
• extend from thyroid cartilage into arytenoid cartilages at the vocal processes. Runs through lamina propria. (filamentous strands like cotton fibers). Strengthen medial edges of VF to limit stretching.
• What is the function of the aryepiglottic and the thyroepiglottic muscles for singing?
• Resonance. 
• What is phonation threshold pressure (PTP)?
• The 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 adduction precedes breath energy. 
• Aspirate/breathy: breath flow starts and VF are slowly adducted until Bernoulli enables oscillation. 
• Balanced/simultaneous: adduction/airflow begin at same instant. 
• What is flow phonation?
• When sustained tones have perfect union of airflow and adductor tension. 
• What happens if we increase breath pressure with constant adductory tension?
• The sound will get slightly louder but rise in pitch and can potentially become aspirate from excess air. 
•  What happens is you increase glottal resistance at the same time as you increase breath pressure?
• VF will oscillate at a higher amplitude/grater range of motion and close faster during each cycle, resulting in a crisper, firmer cessation of airflow, increasing sound wave amplitude. 
• As amplitude increases, how does this affect the glottis? What happens to help this situation?
• The glottis must work harder to resist sub glottal air pressure. The adductor muscles (LCA and IA) and TA contraction create medial tension in glottis. 
• How do we increase vocal fold thickness, and what affect does this have on the sound?
• The TA contracts in isometric antagonism with CT muscles, and this increases VF mass that is in oscillation because it widens contact area between folds. 
• 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, but a lower absolute maximum. 
• How do pitch and amplitude relate to each other?
• Doubling the fundamental frequency increases amplitude at the glottal sound source by 6 dB. 
• How is the time that the glottis remains open impacted by adduction and pressure changes?
• As adduction/pressure increases, length of glottis opening time becomes shorter. 
• What is the estimated times of the various phases in q quiet tone vs a louder tone?
• quiet: open phase for about 50% of the time, closing for 37%, and completely closed for 13%. 
• Louder: 33%, 37%, 30%. 
• What is the open quotient?
• The time the glottis is open during each cycle. 
• How does the open quotient relate to amplitude?
• Amplitude increases as the open quotient fell from 1.0, reaching a peak between 0.5 and 0.6. 
• Why is it wrong to just blow harder to get louder?
• You’ll probably sing too sharp; and you want a balance between VF vibration and breath support. 
• In very general terms, what must the vocal folds do to change pitch?
• If the vocal folds are longer, then the pitch is lower; if they’re shorter, the pitch is higher. 
• How does the body/cover model affect pitch change?
• The louder the note, the more the body of the vocal folds vibrate; the quieter, mostly just the cover. Same with pitch; lower=more body, higher=more cover. 
• How do pitch and intensity overlap in terms of vocal fold function?
• Higher pitches=longer/stiffer/narrower VF, Louder=thicker VF/more glottal resistance. 
• How do the CT and TA work together to control pitch and amplitude?
• CT pulls folds for tension to appropriate pitch, while TA counter that tension for amplitude. 
• Describe how variations in air pressure have different impacts on low vs. high frequencies.
• High pitches tend to require higher sub glottal air pressure than low pitches. 
• 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 base of esophagus. Contractions narrows pharynx and elevates larynx. 
• What is ossification? 
• Gradual transformation of cartilage to bone. 
• What is the downside of the flexibility of the thyroid cartilage in young people.
• Leads to vocal instability and unpredictability. 
• Describe the actions of swallowing
• Soft palate lifts, closing off nasal port. Tongue elevates and retracts, pushing food into throat. Walls of pharynx constrict to assist. Larynx lowers and epiglottis returns to resting position after swallowing. 
• Describe the pharyngeal constrictor muscles.
• superior: wraps around top of vocal tract in naso- and oropharynx area, attaches to skulls and mandible. 
• Middle: attach to hyoid bone and stylohyoid ligament (from base of skull to just below ear canal opening). 
• Inferior: bottom of this muscle complex and attaches to thyroid laminae/sides of the cartilage between two horns and the cricoid cartilage. 
• The upper two narrow pharynx and transport food to esophagus. Inferior constricts pharynx and lifts larynx. 
• What does gola aperta mean?
• Sensation of open throat. 
• How do we open the throat? 
• The soft palate can be elevated slightly, but remainder of vocal tract, naso-, oro-, and laryngopharynx can only relaxed. Passive relaxation, in which “doing nothing” is “doing something.” 
• What are the two ways in which laryngeal elevation can occur?
• It’s lifted directly through an attachment to the thyroid or cricoid cartilage.
• It’s 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 muscles. It lifts the larynx and partially closes the gap between thyroid cartilage and hyoid. 
• Which muscles are indirect laryngeal elevators?
• Poor support, excess jaw and/or tongue tension, inappropriate tuning of formants. 
• Digastric (posterior/anterior), styloglossus, stylohyoid, genioglossus, geniohyoid, 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 becomes fixed into place; lowers the jaw, but elevates the larynx. 
• Which muscles can both depress the jaw and raise the larynx?
• Styloyoid, mylohyoid, and geniohyoid. 
• Which muscles are laryngeal depressors?
• Anterior omohyoid, sternohyoid, posterior omohyoid. 
• What is the ideal laryngeal position for classical singing?
• A low, depressed larynx or resting position. 
• How does the vertical position of the larynx change as we age? Be specific.
• At birth: base of cricoid is at level of third cervical vertebra. 5: descended to C5. Puberty: larynx to C7 with some additional lowering throughout adulthood. 
• What is tracheal pull (tug)?
• When the descending diaphragm pulls down the lungs, bronchial tubes, trachea, and larynx. 
• Which nerves serve the larynx?
• branches of the vagus nerve, a.k.a. 10th cranial nerve. Superior laryngeal nerve and the recurrent laryngeal nerve.