Phonation W7

Question 1

larynx

Answer 1

2 biological purposes guard dog of airway - closes during swallowing and reflexive cough on aspiration, valve for thoracic fixation - valsalva maneuvre secondary function - phonation for voice production

Question 2

Physics of sound

Answer 2

displacement of air particles

intensity = loudness (amplitude), unit of measure is dB

frequency = pitch, number of cycles per second, unit of measure is Hz

Question 3

periodic sounds

Answer 3

acoustic waves repeat consitently and predictably

Question 4

aperiodic sounds

Answer 4

no discernible patterns to acoustic waves

Question 5

human voice

Answer 5

complex tone - made up of numerous frequencies/harmonics

lowest frew = fundamental freq’ F0

created by vibration of entire length of vocal fold

adult m F0= 125hz

adult f F0= 200hz

child F0= >300hz

vibrations inside vibrations - inverse relationship between length and frequency, multiple harmonics cause by portions of the vocal folds vibration e.g. halves, thirds, fourths, fifths etc

Question 6

modify vocal tone with longitudinal tension

Answer 6

tension changes that come from changes in the length of the vocal folds

as vocal fold is lengthened mass decreases, as vocal fold is shortened, mass increases

inverse relationship between mass and tension

increased tension = higher frequency

Question 7

modifying vocal tone with medial compression

Answer 7

the pressure of vocal fold adduction i.e. how hard the vocal folds are closed

contact between vocal folds can range from light to tightly compressed

increased medial compression provides greater resistance to subglottic pressure

• less subglottic pressure required to abduct lightly contacting vocal folds
• subglottic air pressure will build until medial copression is overcome
• release of air is therefore smaller for light medial compression and greater for extreme medial compression
• greater air release = greater intensity of sound

Question 8

suprasegmental features (prosody)

Answer 8

sound features that apply to syllables, words, utternaces etc

stress - intenstiy, attribute, content, contrast, present

intonation - pitch

intensity changes - changes in medial compression, louder voice = more medial compression

pitch changes - changes in longitudinal tension, higher pitch = more VF tension

occasionally adjustments of medial compression make changes to longitudinal tension, reflexive tensing of VFs at greater intensity

Question 9

whisper

Answer 9

voiceless

mebranous portion adducted, cartilaginous portion abducted - glottal chink

turbulence through the glottal chink creates what we hear as a whisper

Question 10

myoelastic aerodynamic theory of phonation

Answer 10

MATP

subglottic pressure - force of air on inferior surface of adducted vocal folds

elasticity - manipulability

bernoulli effect

air is exhaled from the lungs, vocal folds are adducted, creates obstruction to exp air flow,

subglottic pressure builds up, subglottic pressure overcomes median compression,

because of elasticity of vocal folds, small glottis is created along a portion of the length of folds

sublgottic air pressure is released as airflow through glottis

increase of air velocity through folds (benoulli) creates a drop in pressure between the folds

folds are adducted again due to relative vacuum from increased velocity (bernoulli) and due to elastic recoil of vf

also air flow is outwards because of the laws of fluid mechanics

Question 11

the bernoulli effect

Answer 11

an increase in fluid velocity = a decrease in pressure exerted by that fluid

a decrease in fluid velocity = an increase in pressure exerted by that fluid

airplane wing

Question 12

alternative theory - cover body model

Answer 12

observation that vf vibrate for brief periods when no energy source (air flow) is present

proposes vf structure allows them to maintain vibration once phonation is initiated

body - thyroarytenoid muscle

cover - epithelium and superficial lamina propria layer

cover and body are connected but move independently of each other

allowing masses within the cover to be displaced in wavelike fashion

regions of convergent and divergent airflow through glottis

the asymmetry in pressures caused by convergent and divergent airflow is called vertical phase difference

air pressure is greater during convergent airflow

Question 13

phonation

Answer 13

vf vibration occure when vfs are nearly or completely adducted, cannot occur is over or under adducted

muscles gives us control over when we do and do not want to make sound

Question 14

intrinsic laryngeal muscles

Answer 14

3 adductors - lateral cricoarytenoid, transverse and oblique arytenoids

1 abductor - posterior cricoarytenoid

Question 15

muscles and vf adduction

Answer 15

lateral cricoarytenoid and interarytenoid muscles contract during exhalation

• IA adducts arytenoids and therefore vf

LCA rotates muscular process and therefore adducts and pulls down the vfs

cumulative result = arytenoids are brought forward, medial and downwards

different contraction levels mediates medial compression

once vfs are adducted they stay adducted throughout phonation

process involves: adduction from muscle contractions, subglottic air pressure build up, subglottic air pressure overcoming medial compression, natural recoil of vfs and vertical phase difference resulting in adduction again

Question 16

vf abduction

Answer 16

job of one muscle - posterior cricoarytenoid

abduction needed to breathe and produce voiceless sounds

Question 17

voiced and voiceless sounds

Answer 17

41 speech sounds - 9 are voiceless p t k f s sh th h tch

vocal folds stay adducted for continuous phonation or string of voice sounds

vocal folds abduct when a voiceless sound is encountered

Question 18

phases of phonation

Answer 18

prephonation phase - duration between when the vfs are halfway open and halfway closed (paramediam position) and when are fully adducted to allow for vibration. required precise coordination with expiration

attack phase - begins when vfs are adducted through the first vibration cycles

Question 19

coordination of attach phase

Answer 19

attack phase starts as exhaled air reaches vfs - simultaneous attack

attack phase begins after exhaled air reaches vfs - breathy attack

attack phase begins before exhaled air reaches vfs - glottal attack