slhs2203: physiology of phonation

power

the expiratory airflow from the lungs generates the power source for voicing

source

the larynx is the source of vocal fold vibration

filter

resonators above the vocal folds filter sounds generated when air passes through the vocal folds

simultaneous vocal attack

adduction of vocal folds and onset of respiration occur at the same time

breathy vocal attack

vocal fold adduction happens after the expiratory airflow begins

hard vocal attack

vocal fold adduction happens before expiration occurs

myo (muscle)

vocal folds are adducted due to the contraction of the intrinsic muscles of the larynx

elastic

elastic properties of the vocal folds allow them to return to their original shape after being stretched, compressed, and deformed

aerodynamic

the force of subglottic pressure and resulting velocity of airflow as air passes through the glottis

bernoulli principle

as air passes through the glottis, the velocity of airflow increases, resulting in a decrease in pressure; this increase in velocity creates a negative pressure that pulls the vocal folds back together

cycle of phonation

1. vocal folds adduct/come together

2. the subglottal pressure from the lungs pushes the adducted vocal folds open, creating the glottis

3. air begins flowing at a high velocity

4. the pressure drops, sucking vocal folds back together

body-cover theory

the structure of the vocal folds influences their velocity

body of vocal folds

primarily the thyroidarytenoid muscle

cover of vocal folds

includes the epithelium and the superficial layer of the lamina propria; the flexible properties of vocal fold cover allow it to move freely and vibrate over the body, creating a mucosal wave.

nonlinear source-filter coupling theory

pressure changes in the filter influence the production of frequencies by the source; feedback from above and below the level of vocal folds may influence patterns of vibration

frequency

the cycle of vocal fold vibration per second; measured in Hz

fundamental frequency (F₀)

the lowest and primary frequency; influenced by length, size, and stiffness of vocal folds

harmonics

whole number multiples of F₀

pitch

the perceptual correlate of frequency

pitch range (F₀ range₎

the difference between the highest frequency and the lowest frequency; healthy vocal folds can produce a range of two octaves

optimal pitch

the ideal frequency of vocal fold vibration, requiring the least amount of effort

habitual pitch

the frequency of vocal fold vibration used most frequently by the indivdual

amplitude

loudness; the degree of lateral excursion of the vocal folds from the midpoint; measured in decibel (dB)

periodic VF vibration

the time it takes to complete each cycle is periodic

aperiodic VF vibration

inconsistent cycle completion time

jitter

F₀ variability cycle-to-cycle

shimmer

amplitude variability cycle-to-cycle

modal register

the typical speaking voice

glottal fry

low frequency; crackly quality; vocal folds are short and thick, requiring low subglottal pressure

falsetto

vocal folds are stretched and extremely thin; produces a high pitch

organic voice disorders

result from alterations in respiratory, laryngeal, or vocal tract mechanisms; structural or neurogenic

functional voice disorders

results from inefficient use of vocal mechanisms

laryngitis

raspy voice due to vocal fold inflammation

vocal function exercises

work to strengthen and coordinate laryngeal muscles and increase efficiency of airflow and vocal fold vibration

lee silverman voice treatment

aims to improve respiratory support, laryngeal muscle activity, and loudness

semi-occluded vocal tract exercises

involve narrowing any supraglottal point to maximize safe interaction of vocal fold closure/vibration for phonation