Phonatory System- Physiology, Acoustic/Perceptual Characteristics, and Observational Methods

phonatory system speech functions

produce voiced/voiceless sounds

modify pitch

modify loudness

influence voice quality

muscle for vocal fold abduction

posterior cricoarytenoids

phonotory system biological functions

prevent air from escaping lungs

prevent foreign substances from entering lungs

expel foreign substances from lungs

larynx biological function

swallowing

larynx role in swallowing

protective role by preventing solids or liquids from entering lower respiratory tract

3 levels of protection by larynx

1. larynx pulled up and forward to move epiglottis over top of airway and pull larynx out of way of food

2. epiglottis pulled down to cover larynx entrance

3. glottis closed tight to shut off airway and stop breathing momentarily

these muscles pull larynx up and forward

digastric anterior

mylohyoid

geniohyoid

pulls epiglottis down

aryepiglottis muscle

these muscles close glottis

lateral cricoarytenoids

transverse arytenoid

oblique arytenoid

glottal cycle

cycle of vocal fold vibration that occurs during phonationph

phonation

production of speech sound

two stages of the glottal cycle

prephonation and phonation

prephonation stage of glottal cycle

occurs as exhalation phase is about to begin

vocal folds are abducted

glottis is closed

4 phases of phonation

1. closed

2. opening

3. closing

4. closed

phase one of phonation stage of glottal cycle

closed

• vfs are adducted

• glottis is closed

• exhaled airflow is blocked

  • alveolar pressure is building

alveolar pressure AKA

tracheal pressure

phase two of phonation stage of glottal cycle

opening

• alveolar pressure increases enough to force vocal folds appart

• glottis opens from bottom to top

• exhaled air flow resumes

stage 3 of phonation stage of glottal cycle

closing

• air flow continues

• alveolar pressure decreases

  • allows vfs to rebound

• glottis narrows from bottom to top

• called vertical phase difference

vertical phase difference

difference in the phase bewteen upper and lower parts of vfs- vfs close from bottom to top during closing phase

stage 4 of phonation stage of glottal cycle

closed

• glottis closes

  • cycle begins again

one vocal fold vibration

one complete glottal cycle

medial pressure or compression

muscular force with which vocal folds are adducted or pressed together at midline by ADDuctor muscles

glottal cycle achieves

converts air pressure of free airflow to alternating air pressure

alternating air pressure of glottal cycle

compression + rarefaction = sound wave

how much alveolar pressure in cm h20 needed to initiate glottal cycle

minimum of 3 cm h20 (soft speech)

phonation threshold pressure (ptp)

minimal alveolar pressure needed to initiate glottal cycle depending on how loud you want to speak

phonation threshold pressure is related to

vocal intensity

doubling cm h20 results in _________ db SPL increase in vocal intensity

8-12 db SPL

db SPL

decibel of sound pressure level; used to measure intensity of sound

vocal intensity

strength of sound produced by the voice

vocal pitch

relative highness or lowness of a tone as perceived by the ear; related to glottal vibrations

higher pitch = higher/lower hertz

higher

lower pitch= higher/lower hertz

lower

fundamental frequency

average number of glottal cycles per second

adult male mean fundamental frequency

125 hertz

adult female mean fundamental frequency

225 hz

how does fundamental frequency change across lifespan

changes in average hz

changes in vocal fold length and thickness

how does fundamental frequency change across lifespan for females

drops as you age

how does fundamental frequency change across lifespan for males

drops a lot by young adult and then raises as they age

how does fundamental frequency change across 1st ten years of life

average drops due to chagnes in vocal fold thickness and length with little difference between male and female

how does fundamental frequency change during puberty

male drops dramatically due to longer, thicker vfs

female drops somewhat for similar reasons

thicker vfs result in higher/lower hertz

lowert

thinner vfs results in higher/lower hz

higherth

thyroid angle

angle at which the two halves of the thyroid cartilage meet in front of the larynx

thyroid angle for females

120 degrees

thyroid angle in males

90 degrees

result of lower thyroid angle in males

longer vfs and vocal prominence

how does fundamental frequency change after age 60

male increases due to vf thinning

female drops due to thickening

increased pitch/ number of Hz is caused by

• Shorter glottal cycles

• Lengthen vfs

• Increase vf tension

• Raise larynx

• Decrease vf compliance

decreased pitch/hertz is caused by

• longer glottal cycles

• decreased tension

• shortened vfs

• lower larynx

  • increased vf compliance

for most changes in pitch required for speech prosody, modest changes in _______ are sufficient

vocal fold length

role of glottal cycle in pitch control

changes number of glottal cycles per second to change pitch

the longer the glottal cycle is, the higher/lower the pitch

lower

the shorter the glottal cycle is the higher/lower the pitch

higher

how is frequency of glottal cycle changed, thus changing pitch?

glottis changes shape AND vfs get thinner and longer/thicker and shorter

vocal fold compliance

elastic properties of vocal folds affect their response to aerodynamic forces, especially vf sstiffness or tension

vocal fold compliance analogy

short thick relaxed

• big belly

• vfs yield to each other

• floppy

long thin stiff

• tight six pack

• collide and bounce off each other

  • tense

vocal fold excursion

lateral movement of vocal folds away from midline as air passes through glottis

three mechanisms for pitch control

1. change of vf length

2. change of vf tension

3. change of height of larynx

increasing vf length for pitch control

lengthening vfs increases tension which decreases compliance —> long, thin, stiff vfs

result of increasing length of vfs

increased number of glottal cycles= high pitchin

muscle that increases vf length

cricithyroid

decreasing vf length for pitch control

shortening vf decreases tension and increases compliance—> short, thick, relaxedre

result of shortening vfs

decreased number of glottal cycles—> lower pitchmus

mucles for shortening vfs

contract thyroarytenoids and relax cricothyroids

thyroarytenoids known as

tensor muscles

how is vocal fold tension changed

by changing what the thyroarytenoids are doing

how is extra high pitch achieved

contract both cricothyroids AND thyroarytenoids

how is extra low pitch achieved

relax both thyroarytenoids AND cricothyroids

larynx is raised for high/low pitch

high

larynx is lowered for high/low pitch

low

changing height of larynx is used mostly for

singing

muscles used to raise larynx

suprahyoids

muscles used to lower larynx

infrahyoids

loudness

a perceptual event related to vocal intensity or amplitude of sound or sound pressure level

corresponds to alveolar pressure

loudness is changed by changing

aerodynamic forces

muscular forces

aerodynamic forces

aerodynamic forces and loudness

change volume of air and change alveolar pressure

muscular forces and loudness

change medial compression which influcence resistance to airflow

aerodynamic forces and loudness

changes based on previous info from respiratory system

quiet breathing volume requirements

10-15% of vital capacity above resting volume (50-55% VC)

conversational speech volume requirements

25% of vital capacity above resting volume (65%VC)

loud speech volume requiremnets

40% of vital capacity above resting volume (80%VC)

soft speech ptp pressure requirements

3 cm H20

normal speech pressure requirements

7 cm h20

loud speech pressure requirments

11 cm h20

increased medial compression results in

greater resistance to airflow and alveolar pressure

decreased medial compression results in

relaxed glottal closure which results in less resistance to air flow and alveolar pressure

forces that increase loudness/vocal intensity

• aerodynamic forces: increase volume of air and alveolar pressure

• muscular forces: increase medial compression

  • increase forceof adductors to get firm glottal closure

decreasing loudness/intensity

• aerodynamic forces: decrease volume of air and alveolar pressure

• muscular forces: decrease medial compression

  • minimize force of adductors to get relxed glottal closure

forces behind whispering

• aerodynamic forces: maintain steady air flow

• muscular forces: adjust vocal fold position so no phonation occurs

  • lateral cricoarytenoids only

whisper triangle

when whispering, vocal folds are adducted but triangular gap is left between arytenoids

glottal spectrum

sound consisting of fundamental frequency and its harmonics; influences distinctiveness of voiced sound we hear

perturbations

a small, temporary change in the vocal system that affects the output of the voice

vibratory irregulariteis

vf vibration is not completely periordic due to vf tissue characteristics (aperiodic)

3 acoustic measures of vf irregularities

jitter

shimmer

noise to harmonic ratio

jitter

slight variation in cycle to cycle timing

shimmer

slight variations in amplitude

noise to harmonic ratio (NHR or HNR)

proportion of noise to harmonic sound in voice in decibels

breathy voice has high/low shimmer

high

horse voice has high/low jitter

high