PHYSIOLOGY OF PHONATION

protect the lungs

• deep inhalation-cords widely abducted
• tensing and tight adduction of the vocal folds
• elevation of the larynx
• positive subglottal air pressure to blow the vocal folds apart
• result-max air flow for clearing the airway

have negative effects on vocal folds

• increased resp effort
• tightening of the laryngeal musculature

helps the clinician determine whether or not the vocal folds are approximating

process of capturing air within the thorax which gives the muscles a structure on which to push or pull

• 1. deep inhale
• 2. tightly adduct vocal folds>thorax becomes a rigid frame
• 3. if the thorax is not fixed, the forces will act on the thorax>the rib cage being depressed

remember the airflow increase, decrease pressure

• the vocal folds are a constriction in the vocal tract
• air makes a "detour" around the folds
• at point of constriction, air pressure decrease but there is an increase in velocity of the flow

tissue restoring forces-ability to return to original shape after being distorted

• 1. phonation begins basically with an expiration (air volume and air pressure changes)
• 2. when the vocal folds are apporximated, subglottal pressure builds up
• 3. subglottal pressure increases to a point where the vocal folds are blown apart beginning vibration (vfs do not need to approximate completely for phonation to begin
• 4. as the airflow passes between the vfs, transgolttal pressure drops
• 5. due to the mass of the vfs and the bernoulli effect, they come back together again
• 6. the next cycle begins

• 125 times per second for men (hz)
• 225 for women
• 265 for prepubertal child

tension, length, and mass (per unit of length)

• used for speech. includes the following steps:
• 1. vocal attack-adduct the vocal folds
• 2. hold vocal folds in a fixed position-to sustain phonation
• 3. abduct vfs to terminate phonation

the process of bringing the vfs together to begin phonation-requires muscular action

• three types of attack:
• simultaneous attack
•   when we initiate phonation using sa, we...
•       -coordinate adduction and onset of exhalation/expiration so that they occur simultaneously
•       -vfs reach a critical degree of adduction at the same time that the exhaled air flow is adequate to support phonation
• breathy attack=the exhalation/expiration begins before the vfs are adducted
• glottal attack=adduction of the vfs prior to airflow
•  

requires maintenance of a laryngeal posture through tonic (sustained) contraction of muscles

• place and hold the vfs in the airstream to sustain vibration
• FYI=vibration of the vfs is not the product of repeated adduction and abduction of the vfs. during sustained phonation the vfs are in a steady state, tonic contraction to control fundamental frequency and to stabilize intensity (aerodynamics and vfs elasticity)

requires that the vfs adbuct

refers to the pattern of activity that the vfs undergo during one cycle of vibration (one opening and closing sequences)

refer to differences in the mode of vibration of the vfs

• 1. vocal fundamental frequency-the one primary frequency of vibration
• 2. glottal fry-crackly, rough. low pitched voice-often weak
• 3. falsetto-vfs extremely thin, stretched, tense which decreases the amount of movement (opening and closing)

medial compression is greatly increased>strident, harsh sound and vocal abuse

is inefficient, wastes air, does not damage the mechanism

• pitch is the psychological correlate of frequency
• as frequency incre (number of vibratory cycles of the vfs per second) pitch incre, and as frequency decreases, so does the pitch 

• optimum pitch-what is best for the indiv, it is a function of mass and elasticity of the vfs (difference between males and females)
• habitual pitch-the one we use
• pitch range-low to high

stretching and tensing (ct and thyrovocalis)

• loudness is the psychological correlate of intensity
• remember that the vfs open and close as a result of the air pressure beneath them and the airflow between them
• we increase subglottal pressure to increas vocal intensity

• intramembraneous portion of the glottis
• anterior 2/3
• cartilaginous portion of the glottis
• posterior 1/3