Transcript Phonation
• • • • • 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. • • • • Innervation Extrinsic muscles Intrinsic muscles How the vocal folds vibrate • Initiating vibration • Pitch • Registers • 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 pitch Hixon, 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 Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 97. • 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 Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 100. • PCA: • Rocks arytenoids away from midline • ABducts the vocal folds • LCA: • Rocks arytenoids toward midline • ADducts the vocal folds Hixon, T.J., et al. (2008). Preclinical Speech Science: Anatomy Physiology Acoustics Perception. Pg. 107. • 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. • • • • Innervation Extrinsic muscles Intrinsic muscles How the vocal folds vibrate • Initiating vibration • Pitch • Registers • 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. • • • • Innervation Extrinsic muscles Intrinsic muscles How the vocal folds vibrate • Initiating vibration • Pitch • Registers • Phonation threshold pressure (PTP): smallest subglottal pressure needed to start self-sustained oscillation • For low frequency phonation, PTP is around 3-4 cm H20 • Average pitch: • Women: 220 Hz • Men: 130 Hz • Registers • Chest (Low pitches) • Middle/Mixed (Middle pitches) • Head/Falsetto (High pitches) Zemlin, pg 166.