Physiology of PhonationCh. 5

Nonspeech Laryngeal function

Protection is the most important role

Prohibits entry of foreign objects into the lungs

Cough- response by the tissues of the respiratory

passageway to an irritant or foreign object Mediated by Vagus nerve Deep inhalation-widely abducted vocal folds,

followed by tensing and tight adduction of the vocal folds and elevation of the larynx

Arytenoids are rocked for adduction and directed downward, providing more force

Nonspeech Laryngeal Function

Throat Clearing Not as violent as a full cough Build pressure in the subglottal region and

clamp the vocal folds shut to restrain the pressure

Places vocal folds under a great deal of strain Involve the muscles of adduction;

lateral cricoarytenoid, arytenoids and thyrovocalis.

Nonspeech Laryngeal Function

Abdominal fixation Capturing air within the thorax to provide the

muscles with a structure to push/pull Similar to a cough Take in a large breath, tight adduction of the

vocal folds Thorax becomes a rigid frame Some air may escape through the adducted

vocal folds and you may “grunt” when lifting something heavy

Nonspeech Laryngeal Function

Breathing Normal breathing requires the vocal folds to be

abducted During forced exhalation (like when exercising)-

the need for air causes you to increase the abduction of the vocal folds

Laryngeal Function for Speech

Bernoulli Effect This explains how we maintain phonation Need a constant volume flow of air Vocal folds become a source of turbulence in the

vocal tract Effects of constricting a tube during air flow As it flows through the constriction- the rate

(velocity) of flow increases, however, the pressure decreases

Vibration of the vocal folds is the product of airflow interacting with the tissue in the absence of repetitive muscular constriction

Bernoulli Effect

Laryngeal Function for Speech

Attack Process of bringing vocal folds together to

begin phonation, requires muscular action

Simultaneous vocal attack-coordinate adduction and onset of respiration so that they occur simultaneously (i.e. say the word “zany”- you start the flow of air before voicing)

Laryngeal Function for Speech

Breathy vocal attack-starting significant airflow before adducting the vocal folds (i.e. running speech “Harry is my friend.” you can feel the air flow past your lips

Glottal attack- adduction of the vocal folds occurs prior to the airflow, much like a cough (i.e. bring vocal folds together like you are going to cough- and then say /a/, or say “okay, I want the car.”

Hard Glottal attack- an attack is misused- too much force- causes damage to vocal folds

Laryngeal Function for Speech

Termination When phonation stops the vocal folds abduct We pull vocal folds out of the airstream far

enough to reduce the turbulence, using muscular action- the vocal folds stop vibrating

It occurs many times during running speech

Adduction

Is constant in all types of phonation and attack

The arytenoid cartilages move in three dimensions: rotating, rocking, and gliding

Primary movement for adduction is inward rocking

Combined forces of the cricothyroid and posterior cricoarytenoid cause the entire glottis to lengthen

Vocal Fold Nodules

Aggregates of tissue arising from abuse- Unilateral or Bilateral

Continued abuse results in the formation of a protective layer of epithelium that is callous-like

Usually on the juncture of the anterior and middle thirds of the vocal folds- greatest impact during phonation

Yelling, screaming, cheerleading, singing

Laryngitis-inflammation of the larynx, hoarseness ad possible loss of voice (aphonia). Swelling of the vocal fold tissue with a breathy voice Can be caused by vocal hyperfunction (over adduction of the

vocal folds) After a thrilling football game

Vocal Nodules

Laryngitis

Laryngitis-inflammation of the larynx, hoarseness ad possible loss of voice (aphonia). Swelling of the vocal

fold tissue with a breathy voice

Can be caused by vocal hyperfunction (over adduction of the vocal folds)

After a thrilling football game

Sustained Phonation

Vocal attack and termination requires muscular action

Sustained phonation requires maintenance of a laryngeal posture through sustained contraction of musculature.

Vocal folds are held in place- it is not the product of repeated adduction and abduction- muscle spindles embedded within the thyrovocalis and thyromuscularis serve the function in holding sustained posture

Vocal Register

Mode of vibration- pattern of activity that the vocal folds undergo during a cycle of vibration

Three registers-differences in the mode of vibration of vocal folds Modal register Glottal fry or pulse register Falsetto

Modal Register

Pattern of phonation used in daily conversation

Vertical mode of phonation is when the vocal folds open from bottom to top and close from bottom to top- like a wave

Primary frequency of vibration- vocal fundamental frequency

Anterior-Posterior dimension of phonation- vocal folds open from posterior to anterior but closure is made by contact at the medial edge

Glottal Fry

Also called “fry, pulse, and straw bass” voice

Crackly, popcorn quality of voice

Low in pitch, sounds rough

Frequencies as low as 30 Hz to 80-90 Hz

Low subglottal pressure and tension of the vocalis is reduced

Vibrating margin is flaccid and thick

Lateral portion of the vocal folds is tensed – strong medial compression with short, thick, vocal folds and low subglottal pressure

Syncopated mode of vibration- a secondary beat for every cycle- the vocal folds don’t just vibrate slower, but differently

Falsetto

Vibratory pattern that varies from modal production

Vocal folds lengthen and become thin and “reed like”

Vibrate along the tensed, bowed margins

Make contact only briefly and the degree of movement is reduced

Thin, high- pitched voice

Whistle register- above falsetto- product of turbulence on the edge of the vocal fold- frequencies as high as 2500 Hz

Pressed and Breathy Phonation

Pressed phonation Medial compression is greatly increased Increase in stridency or harsh quality Increase in abuse to the voice Stronger, louder phonation Forceful adduction often results in damage to

vocal fold tissue

Pressed and Breathy Phonation

Breathy voice Vocal folds are inadequately approximated Vibrating margins permit excessive airflow

between then Inefficient and causes air wastage May signal the presence of vocal nodules,

polyps or laryngeal cancer

Whispering

Not a phonatory mode

No vibration of the vocal folds

Vocal folds are partially adducted and tensed to develop turbulence in the airstream

The turbulence is the noise you use to make speech

Arytenoid cartilages are rotated slightly in but are separated posteriorly

No voicing, however, it is strenuous and can cause vocal fatigue

Intensity

Relative power or pressure of an acoustic signal, measured in decibels (dB)

Amount of pressure exerted by the sound wave

Ventricular Phonation

False or ventricular vocal folds are technically unable to vibrate for voice

In some instances- clients may use ventricular phonation as an adaptive response to severe vocal fold dysfunction

Forces the lateral superior walls close together

Phonation is deep, raspy

Sustained and Maximum Phonation

P. 237

Sustain /ah/

Sustain /s/

Sustain /z/

Pitch

Psychological correlate of frequency

As frequency increases, pitch increases

Vocal folds tend to vibrate at the same frequency when mass and elastic elements remain constant

Frequency of vibration changes when mass and elastic elements change

Optimal Pitch

Vocal fold vibration that is most appropriate for an individual

Most efficient for a pair of vocal folds

Considered 1/4th octave above the lowest frequency

Can be estimated from a throat clearing

Varies from gender and age

Females average 212 Hz, Males 132 Hz

Habitual Pitch

Frequency of vibration of vocal folds that is habitually used during speech

Ideally this would be the same as optimal pitch

The choice to use an abnormally higher or lower fundamental frequency is often not a conscious decision

When forcing vocal folds to extremes of their range of ability- greater effort and physical fatigue

Average Fundamental Frequency

Frequency of vibration of sustained phonation or conversational speech

Reflects habitual pitch over a longer averaging period

Use conversational speech or reading tasks to accurately reflect

Pitch range- difference between the highest and lowest frequencies- capable of approximately two octaves

Pitch Changing

Stretching and tensing the vocal folds

Use the cricothyroid and thyrovocalis muscles

Changeable elements are tension, length and mass through elongation

Cricothyroid- thyroid tilts down, lengthening the vocal folds and increasing fundamental frequency

Thyrovocalis- pulls cricoid and thyroid closer

Pitch changing

Posterior cricoarytenoid- has muscle spindles that moitor and maintain tonic muscle length

Cricothyroid makes the gross adjustment, Thyrovocalis fine tunes the adjustment

Increased subglottal pressure is a response to the increased tension

Mass is rearranged by lengthening or shortening

Relaxing the vocal folds- contraction of the thyromuscularis- folds are relaxed and shortened becoming more massive and less tense

Intensity

Loudness is the pscyhological correlate of intensity

Physical measure of power or pressure

Increase the vigor with which the vocal folds open and close

Subglottal pressure and flow provide the energy

Increase subglottal pressure to increase vocal intensity

Changing Intensity

Increased medial compression of vocal folds Vocal folds are tightly compressed Takes more force to blow them open They close more rapidly Stay closed because they are tightly

compressed

Intensity and Frequency are controlled independently, however, it is difficult to increase intensity without increasing pitch unless you are trained. Intensity and frequency increasing together is a natural process

Clinical Considerations

Perturbation (jitter) Measures cycle-by-cycle variability in

phonation- measures perception of “hoarseness”

Increased mass (vocal nodules) will increase perturbation

Neuromotor dysfunction will increase perturbation

Provides another measure of how the phonatory system is functioning

Clinical Considerations

Prosody System of stress used to vary the meaning in

speech Elements include pitch, intonation, loudness,

stress, duration and rhythmn Provides information concerning emotion and

intent and can provide clearer meaning

Diadochokinesis Alternation of articulators (puh tuh kuh) Assesses the coordination between the phonatory

and articulatory systems