Phonation Physiology

Functions of the larynx

• respiration

• Airway protection

• Thoracic fixation

• Sound generation

Main laryngeal functions during speech

• voicing

• Voiceless

• intonation

Vocal folds

Masses that can be set into vibration, have mass and elasticity

Vocal folds abduction during quiet and forced respiration

During normal, quiet, respiration, the vocal folds are abducted to provide a width of about 8 mm in the adult

During forced respiration, the need for air causes you to dilate, or open, the respiratory tract as widely as possible, doubling that width

The effect of vocal full mass on vibration rate

As mass increases, the frequency of vocal vibration decreases

The effect of vocal fold length on vibration rate

Provided the same mass, shorter vocal folds have higher frequency, and therefore higher pitch

Elasticity

It is that property of material that causes it to return to its original shape after being displaced

Stiffness

The strength of elastic forces

Myoelastic aerodynamic theory

The vocal phones vibrate, partly because of the forces and pressure Of air and the elasticity of the vocal folds

Bernoulli effect

Given a constant volume flow of air or fluid, at a point of constriction, there will be a decrease in air pressure perpendicular to the flow and an increase in velocity of the flow

Pitch

• The perceptual correlate of frequency

• As frequency increases, cycles per second increase in pitch increases

Optimal pitch

The pitch of vocal fold vibration that is optimal for an individual, Varies depending on age and gender

Habitual pitch

The frequency of vibration of vocal folds that is habitually used during speech

Ideally, this is the same as optimal pitch

Average fundamental frequency

The average frequency of vibration of the vocal folds during some sustained phonation

Pitch range

The range of fundamental frequency for an individual

Changeable elements of the vocal folds

Mass, tension, length

Cricothyroid role in fundamental frequency adjustment

it stretches the vocal folds

Thyrovocalis role In fundamental frequency adjustment

Contraction pulls the cricoid and the thyroid closer together

Vocalis

• medial portion of the thyroarytenoid

• Main mass of the vocal folds

• Tenses the vocal folds and works with the Cryothyroid to stiffen the VFs

Thyromuscularis

• Origin is the thyroid and insertion is the arytenoids Function

• Pulls the arytenoids anywriorly to shorten the VFs

The effect of vocal folds tension on pitch

Increases pitch

The effect of vocal fold mass on pitch

Decreases pitch

Vocal registers

Glottal frye, modal, falsetto

Glottal fry

• lowest frequency

• Vocal folds, close quickly, long closed phase of the cycle

• Folds held tight together

• Free edges bubble sound out

• Popcorn sound

Modal register

The mode of vibration used for daily speaking

Falsetto register

Produced with elongated, tight vocal folds

The relation of subglacial pressure with intensity

There is a direct relation

Laryngoscopy

Visual examination of the lyrics

Two types of Laryngoscopy

Direct and indirect

Direct Laryngoscopy

Direct viewing of the lyrics and adjacent structures by use of laryngeal scope under full anesthesia

Indirect Laryngoscopy

• dental mirror

• Rigid Laryngoscopy

• Flexible Laryngoscopy

Tracheostomy

Surgical creation of an opening into the trachea through the neck

What is the effect of vocal fold masses or paralysis on Subglottal air pressure?

Because vocal folds cannot be completely adducted, The subglacial air pressure will be decreased

Laryngectomy

Surgical removal of the larynx