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phonation/instrumentation

frequency and intensity require variable --------- of the VF layers

stiffness

stress

measure of internal distribution of force per unit area within a material

* force that results in a change in volume or shape of material after it is subjected to external forces (CT)

Strain

Length change of tissue in the direction of the force/ resting length

* when VF’s are stretched or contracted

Tension

Taughtness; pulling force exerted on the VF’s

VF Stress ------ with increasing strain

increases

\------ can stretch more than muscle

cover

\------ builds up stress faster than muscle

cover

Stress-strain relationship is linear or NOT linear?

Not linear

\------ builds up faster when stretched than is released during relaxation

stress

Cover - less connective tissue

* builds up stress faster (more linear than muscle)
* stretch more

Fo

rate of vibration of VF’s

* first harmonic

pitch

perceptual correlate of Fo

Fo is controlled by

CT muscle , TA muscle (stress, dessert vs desert), subglottal pressure, extrinsic muscle activity

frequency depends upon

length, tension, and density

Cover-dominant vibration (body DOES NOT vibrate) in…..

soft or high frequency phonation

decreased mass/unit length

faster movement

* less mass, less inertia

Body + Cover vibration (muscle and L.P. vibrate)

low frequency - moderate to high intensity

* TA = active event

TA contraction unopposed shortens VF’s

* decreases tension on cover, decreased stiffness and increased mass/unit length
* lesser displacement force, lesser restorative force

Depends upon degree to which TA is involved in vibration

low and mid Fo

* decreased stiffness of cover + increased mass/unit dominates

Greater intensity

* increased stiffness of muscle CAN dominate

Psub affects ------- of lateral excursion of VF’s

amplitude

If F0 is allowed to vary freely, dynamic stretch due to Psub increase can result in increases is in Fo of -- Hz per kPa of pressure

20

CT is ----- regulator of Fo

dominant

control of Fo

TA, LCA (intrinsic muscles)

Extrinsic muscle (infra)

sternothyroid and sternohyoid lower larynx, reduce vocal lstrain and lower Fo

Extrinsic muscle (Supra)

Thyrohyoid may raise OR lower larynx depending on activity of suprahyoid antagonist muscles

Geniohyoid may elevate larynx and Fo

amplitude of a sound pressure wave

amount of power in the wave

intensity

power per unit area

intensity increases as the square of the -----

amplitude

Determiners of sound pressure wave amplitude (intensity)

* subglottal pressure (except at high frequencies)
* VF closure
* Vocal tract resonance

Conversational speech average

7 cm H20

Conversational speech range

3-12 cm H20

moderately loud

10 cm H20

loud speech

up to 30 cm H20

Greater intensity

* longer closed phase
* greater build up of Psub
* faster closing
* sharper cut off of GVV
* greater closure
* less energy lost to subglottal space

increasing intensity is a complex interplay of ------- and muscular activity

aerodynamic

What are more active with increased intensity?

Extrinsic laryngeal muscles and thoracic muscles

lombard effect

tendency to increase intensity in high ambient noise

Fo is sensitive to auditory feedback

* feedback of lowered pitch causes individuals to raise Fo
* feedback of auditory masking caused individuals to have difficulty maintaining stable fo

mechanical stress

* tensile
* contractile
* impact
* Inertial
* aerodynamic
* Interarytenoid
* Shear

tensile stress

longitudinal force (CT contraction) = passive

Contractile stress

active

Impact stress

collision + rapid deceleration

* direct relationship with Psub and amplitude of vibration
* variable dependence upon Fo

inertial stress

relevant when VF do not completely contact

aerodynamic stress

air pressure in the glottis

interarytenoid impact stress

contact

* not directly experienced by VF’s but relevant to intrinsic muscle activity

Shear stress

force parallel to surface

* direct relationship with amplitude of mucosal wave
* indirect relationship with VF length

Measurement of Fo and intensity

* habitual voice use levels
* maximum performance tasks
* regularity

habitual voice levels

How does the system perform in ROUTINE function?

reading a passage/counting

maximum performance tasks

What are the physiologic capabilities of the system (performance under mechanical stress?)

* dynamic pitch range

Regularity

how stable is the system?

habitual voice use

mean speaking Fo and intensity

mean speaking Fo and intensity range

* tasks used to assess
* sustained vowel
* reading
* rainbow/grandfather passage
* running speech

perturbation

short term irregularity

Jitter = Fo perturbation

cycle to cycle regularity of the period of vibration (time)(percent difference)

* hoarseness
* WANT < 1 %

Shimmer= intensity perturbation

cycle to cycle regularity of the amplitude of the acoustic waveform

* amplitude variability

Voice Range Profile (Phonetogram)

habitually- we use only a small portion of our physiologic range

Features of VRP

* area of profile
* dynamic range is reduced at extremes
* upper and lower contours tilt upward at higher Fo’s

Airflow

Control Fo and SPL

* measured alongside
* subglottal pressure
* vocal efficiency
* laryngeal airway resistant

Subglottal pressure

* control SPL
* pa pa pa

P vs A

p = subglottal VF are open

a= airflow

airflow is --- when subglottal is high

0

pressure is high airflow is ---

low

measurement method of subglottal pressure

* direct (needle puncture)
* indirect
* use of intra-oral pressure
* airway interruption method

Vocal glottal VF efficiency

measure of the relationship of energy input to output

aerodynamic power

Psub x airflow rate

acoustic power

amount of energy radiated from a sound source per second (measured in watts) (intensity)

true measure of vocal efficiency would assess ratio of aerodynamic power to acoustic power at level of -------

glottis

Cant measure acoustic power at glottis so we use it as is radiated from the ?

lips

vocal efficiency

aerodynamic power (Psub x airflow)/ radiated acoustic power (intensity)

s/z ratio

maximum performance task used to assess integrity of phonatory glottal closure

s and z should be of ----- durations yielding a value of 1

equal

s/z > 1

lower glottal resistance with incomplete closure allowing air to escape

(z is shorter than s)

Maximum phonation time

duration of maximally sustained vowel

* incomplete glottal closure should shorten MPT

MPT of men is ----- than women due to lung volume capacities

greater

phonation quotient (ml/sec)

vital capacity/ maximum phonation time

glottography

analysis of vibratory movements of VF’s during phonation

Stroboscopy

pulsing light to simulate movement at a slower rate than actual movement

* most common clinical diagnostic technique

Talbot’s law

* images < .2 sec appear continuous
* 50 Hz

still image

same frequency as VF vibration

walking image

slightly different frequency

factors affecting phonation threshold pressure

* low viscosity lower PTP


* **low mucosal wave velocity lower PTP**
* **increased approximation of VF in pre-phonatory stage low PTP**
* PTP Raised by increased frequency of vibration