Week 2 Laryngeal Physiology - Study Guide

Review the functions of the intrinsic and extrinsic laryngeal muscles!

• Extrinsic (DMGSTSSO)

  • Digastric

  • Mylohyoid

  • Geniohyoid

  • Stylohyoid

  • Thyrohyoid

  • Sternothyroid

  • Sternohyoid

  • Omohyoid

  Intrinsic (APLTC)

  • Arytenoideus

  • Lateral Cricoarytenoid

  • Posterior Cricoarytenoid

  • Cricothyroid

  • Thyroarytenoid

What three conditions must be present to initiate sound?

• vocal folds must be in phonatory position

• length/tension of vocal folds

• must be airflow from lungs

  • after these three things established, then phonation can start

The vocal folds maintain their vibration partially because of a fluid dynamic
principal called the Bernoulli principal. Please briefly explain the principal. *

• Bernoulli effect sucks the vocal folds together which creates the sound

• intrinsic laryngeal muscles bring vf together, space below (glottis) is closed off

• air stream creates a pressure against closed vf until they are blown apart

• increase in pressure, decrease in velocity (vice versa), kinetic energy increase/static energy decrease

• molecules traveling sides of trachea, when meeting the vocal folds, must travel a greater distance around the fold to meet the molecules traveling up the center of the trachea

• the side molecules increase velocity/kinetic pressure

• static pressure on the surface of vocal folds will decrease

• vocal folds begin to move toward center of trachea bc of pressure difference, eventually meet at midline and airflow ceases

• positive pressure below the vocal folds causes them to open

How does the effect vocal fold length on fundamental frequency differ between modal and falsetto register? Why?*

• when phonation produced in falsetto, fundamental frequency decreases as vf length increases

  • intrinsic muscles are less active in falsetto, less resistance, lighter/breathier vibration

• when phonation produced in modal register, frequency increases as vf length increases

  • vf lengthen and thicken, greater tension/vibratory mass

• length is not the sole factor for control of fundamental frequency

• found that the length of the vibrating portion of the vf decreases as frequency is increased

How does mass affect fundamental frequency in the vocal folds?*

• mass plays a role in frequency control

• as frequency decreases, mass increases, vice versa

• males have lower voices bc they have thicker/bigger vf compared to women

How does tension affect fundamental frequency in the vocal folds?

• affects vibrating frequency

• as tension increases, so too does frequency

• effect of tension on the vf produces changes of frequency

• largest variation of tension occurs at upper frequencies

• difficult to measure tension in human vf

Which part of the range has the greatest frequency change in relation to tension?

• largest variation of tension occurs at upper frequencies, most often produced in falsetto register

Describe how airflow rates may contribute to frequency.*

• relationship btw tension and fundamental frequency differs as airflow rates differ

• airflow may be major determinant of frequency esp for tones whose frequency of vibration is controlled by the rate of airflow

What are three mechanisms that affect sound pressure level of vocal fold vibration? Describe why!*

• vocal intensity

  • increased pressures beneath vf, when released by vf, produce greater intensity

  • subglottal air pressure inc=intensity inc

  • resistance is most important factor

• glottal resistance

  • major controlling mechanism of vocal intensities for low fund freqs

  • not huge factor for higher freqs (airflow becomes dominant variable in intensity)

• spectral characs of tone produced by vf

  • speed of closure of vf will affect spectral features of the glottal tone

What non-laryngeal factors contribute to the sound pressure level of the voice?

Besides spectral characteristics, what also determines the quality of the voice?

• spectral characteristics include:

  • number and amplitude of the frequencies present in a complex tone (vf tone)

• NOT PITCH

• shape and configuration of the vocal tract

  • length, cross sectional area, ratio of oral to pharyngeal cavity size