Phonatory System Lecture 8

• Bone• Cartilage• Ligament• Membrane• Muscle

• Innervation• Extrinsic muscles• Intrinsic muscles• How the vocal

folds vibrate• Initiating vibration• Pitch• Registers

• Vagus (CN X)• Superior laryngeal nerve:

• Cricothyroid (CT)

• Recurrent laryngeal nerve: • Thyroarytenoid (TA)• Posterior Cricoarytenoid (PCA)

• Lateral Cricoarytenoids (LCA)• Interarytenoids (IA)

Blumenfeld, H., 2002, Neuroanatomy through Clinical Cases, Sinauer, Inc.

• Many extrinsic laryngeal muscles

• Thyrohyoid•Elevates larynx

• Sternothyroid•Depresses larynx

Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 112.

• Bulk of the vocal folds• Contractions can result

in:• Shortening the vocal folds

• Pulling thyroid and arytenoid cartilages toward each other

• Increasing the tension of the vocal folds

• Isometric (contracting and not changing length)

• Shorten: decreases pitch• Increase tension:

increases pitchHixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 98.

• When it contracts, it helps to lengthen the vocal folds• It elevates the cricoid arch, and depresses the thyroid

lamina (shortens the space between the cricoid and the thyroid)

• This can help to increase pitch


• CT active and TA passive = increase pitch• Increase length• Increase stiffness

• TA active and CT passive = decrease pitch• Decrease length• Decrease stiffness

• TA and CT contract simultaneously = increase pitch• Increase stiffness

• Work in opposition• PCA:

• Rocks arytenoids away from midline

• Opens the vocal folds

• LCA:• Rocks arytenoids toward midline

• Closes the vocal folds


• PCA: • Rocks arytenoids away from midline

• ABducts the vocal folds

• LCA:• Rocks arytenoids toward midline

• ADducts the vocal folds


• Transverse: • Pulls arytenoids toward each other

• ADducts the vocal folds

• Oblique:• Tips one arytenoid (apex) toward the other (body)

• ADducts the vocal folds Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 101.

• Many theories of vocal fold vibration• Myo-elastic aerodynamic theory of vocal fold

vibration• Nonuniform tissue movement: Multimass

models

• Van den Berg, 1958• Based on Bernoulli equation:

P + ½ pv2 = constant• P = pressure• p = fluid density• v = velocity• Please use this formula- I believe the

formula in your book is incorrect.• This equation states that as pressure

increases, velocity decreases (assuming density is constant)

Based on Titze, I.R. (2000). Principles of Voice Production.

• Van den Berg, 1958• Based on Bernoulli equation:

P + ½ pv2 = constant• Basics of this theory:

• When the vocal folds are closed, pressure builds in the subglottal region

• When the pressure is high enough, it forces the vocal folds open

• The vocal folds continue to open further as air rushes out• Once they reach a maximum opening, the elasticity in the

vocal folds pulls them together• The cycle repeats

• Other theories in between, but this is the most recent

• Explains self-sustained oscillation: as the vocal folds continue to oscillate (vibrate), they are able to sustain the same velocity and width of excursion

Titze, I.R. (2000). Principles of Voice Production.

• Upper and lower parts of the vocal folds do not move as one

• The lower part of the vocal folds moves first, followed by the upper part

• Convergent: lower further apart than upper

• Divergent: upper further apart than lower

Titze, I.R. (2000). Principles of Voice Production.

• Phonation threshold pressure (PTP): smallest subglottal pressure needed to start self-sustained oscillation

• For low frequency phonation, PTP is around 3-4 cm H20

Zemlin, pg 166.

Phonatory System Lecture 8

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