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SPPA 6400 Voice Disorders Stephen M. Tasko SPPA 6400 Voice Disorders: Tasko Some Questions • What is a voice disorder? • Is a voice disorder different form a speech disorder? • Is a voice disorder different from a resonance disorder? • How common are voice disorders? • Who gets a voice disorder? • Why might someone have a voice disorder? • How do you know if someone has a voice disorder? SPPA 6400 Voice Disorders: Tasko Application of Physics and Biology to Voice Production • (Bio)Mechanics • Aerodynamics – Dynamics/statics vs. – Volume, pressure and Kinematics volume velocity (flow) characteristics of air – Active (muscular) vs. Passive molecules system properties • Acoustics – Tissue properties such as stiffness, elasticity – sound pressure wave as a consequence of • Neuromuscular Physiology biomechanical and – Sensorimotor function aerodynamic – Motor “Control” interactions SPPA 6400 Voice Disorders: Tasko Voice Production Within an Integration of Subsystems • Respiration • Phonation • Resonation Colton, Casper & Leonard (2011) SPPA 6400 Voice Disorders: Tasko Voice Production Within Source Filter Theory of Speech Production Source (Phonation) Filter (Resonator) Radiated Sound (What We Hear) Input Spectrum Frequency Response Curve Output Spectrum SPPA 6400 Voice Disorders: Tasko Voice Production: Role of Respiration • Respiratory Aerodynamics – Modify thoracic volume which – Alters alveolar (lung) pressure, which – Results in respiratory airflow – Resisting this airflow using the laryngeal valve allows the establishment of a driving pressure for vocal fold oscillation (or other sound generation) SPPA 6400 Voice Disorders: Tasko Voice Production: Role of Respiration • Respiratory Biomechanics – Passive System Properties • Elastic properties • Environmental forces (gravity) – Active System Properties • Principally muscle activity (inspiratory or expiratory) • Under nervous system control (automatic or voluntary) • Must account for passive properties SPPA 6400 Voice Disorders: Tasko Voice Production: Role of Respiration Lung Volume Above Resting Lung Volume Resting Lung Volume Lung Volume Below Resting Lung Volume SPPA 6400 Voice Disorders: Tasko Voice Production: Role of Larynx Laryngeal Cartilages SPPA 6400 Voice Disorders: Tasko Voice Production: Role of Larynx Ligaments, membranes and joints SPPA 6400 Voice Disorders: Tasko Cricothyroid Joint Actions • Pitch rotation • Horizontal translation SPPA 6400 Voice Disorders: Tasko Cricoarytenoid Joint Action • Pitch and roll – rocking • Translation – sliding or gliding SPPA 6400 Voice Disorders: Tasko Conus Elasticus & Vocal Ligament From Gilroy et al. (2008) SPPA 6400 Voice Disorders: Tasko Laryngoscopic view: Key Structures • True vocal fold – Cartilaginous portion – Membranous portion • False vocal fold • Glottis – Anterior commissure – Posterior commissure • • • • • • • • Epiglottis Arytenoid c. Interarytenoid region Aryepiglottic fold Valleculae Pyriform fossae Posterior pharyngeal wall Opening to esophagus SPPA 6400 Voice Disorders: Tasko Laryngoscopic view: Key Structures • True vocal fold – Cartilaginous portion – Membranous portion • False vocal fold • Glottis – Anterior commissure – Posterior commissure • • • • • • • • Epiglottis Arytenoid c. Interarytenoid region Aryepiglottic fold Valleculae Pyriform fossae Posterior pharyngeal wall Opening to esophagus SPPA 6400 Voice Disorders: Tasko Interior view of larynx Laryngeal Anatomy: The muscles 1. Intrinsic muscles • Both origin and insertion are within the larynx 2. Supplemental and Extrinsic muscles • • Extrinsic: An origin or insertion is within the larynx Supplemental: No origin/insertion within the larynx, but affects the location of larynx in the neck SPPA 6400 Voice Disorders: Tasko Intrinsic Laryngeal muscles Key Actions Position • Adduct • Abduct Tension • Tense • Slacken Length • Lengthen • Shorten ADDUCTION ABDUCTION SPPA 6400 Voice Disorders: Tasko Lateral cricoarytenoid (LCA) Origin: Superior edge of lateral border of cricoid cartilage Insertion: muscular process of arytenoid Action: adducts VF Motor Supply: CN X (recurrent laryngeal nerve) Lateral cricoarytenoid (LCA) Action Posterior cricoarytenoid (PCA) Origin: Posterior (dorsal) surface of cricoid cartilage Insertion: muscular process of arytenoid Action: abducts VF Motor Supply: CN X (recurrent laryngeal nerve) Posterior cricoarytenoid (PCA) Posterior cricoarytenoid (PCA) Action Thyroarytenoid (TA) Often considered to have 2 parts • Vocalis • Thyromuscularis Origin: Internal surface of the thyroid angle Insertion: Vocal and muscular process of arytenoid Action: shorten & adducts VF Motor Supply: CN X (recurrent laryngeal nerve) Thyroarytenoid (TA) Thyroarytenoid (TA) Action From Netter (Inter)arytenoid (IA) Often considered to have 2 fiber types • Oblique • Transverse Origin: Posterior (dorsal) surface of arytenoid surface Insertion: Posterior (dorsal) surface of opposite arytenoid Action: adducts VF Motor Supply: CN X (recurrent laryngeal nerve) Interarytenoid (IA) Action From Netter Cricothyroid (CT) Often considered to have 2 fiber types • Oblique • Vertical Origin: ventral and lateral surfaces of arch of cricoid cartilage Insertion: Caudal border of the thyroid cartilage and anterior surface of inferior horn Action: lengthens and tenses VF Motor Supply: CN X (external branch of superior laryngeal nerve) Cricothyroid (CT) Action SPPA 2050 Speeech Anatomy From Netter 30 Summary of Key Actions SPPA 6400 Voice Disorders: Tasko Nerve supply to larynx • Cranial Nerve X (Vagus N.) – motor supply to all intrinsic muscles – sensory for larynx – 2 branches important for larynx • Superior laryngeal n. – Internal branch » sensory supply – External branch » cricothyroid m. • Recurrent laryngeal n. – all other intrinsic muscles SPPA 6400 Voice Disorders: Tasko Thyroid Gland Supplemental & Extrinsic laryngeal muscles • “Suspends” larynx in the neck • may elevate or depress hyo-laryngeal complex • Suprahyoid muscles: muscles that attach to sites rostral to the hyoid bone • Infrahyoid (aka ‘strap’) muscles: muscles that attach to sites caudal to the hyoid bone SPPA 6400 Voice Disorders: Tasko Suprahyoid muscles SPPA 6400 Voice Disorders: Tasko Infrahyoid muscles SPPA 6400 Voice Disorders: Tasko Vocal Fold Histology SPPA 6400 Voice Disorders: Tasko Vocal Fold Histology Epithelium Basement Membrane Zone (BMZ) connective tissue superficial layer tissue loosely connected to the other layers intermediate layer Lamina propria elastic fibers (stretchy) Vocal ligament deep layer collagen fibers (not stretchy) muscle (TA) SPPA 6400 Voice Disorders: Tasko Myoelastic Aerodynamic Theory of Phonation Necessary and Sufficient Conditions • Vocal Folds are adducted (Adduction) • Vocal Folds are tensed (Longitudinal Tension) • Presence of Aerodynamic pressures (driving pressure) Vocal Fold Oscillation •VF adducted & tensed → myoelastic pressure (Pme ) •Glottis is closed •subglottal air pressure (Psg) ↑ •Psg ~ 8-10 cm H20, Psg > Pme •L and R VFs begin to separate (starting at bottom) •Transglottal airflow (Utg) = 0 As bottom part of fold separates, top part follows is “pulled” along glottis begins to open Psg > Patm therefore Utg > 0 Vocal Fold Oscillation With the glottis now open and glottal airflow (Utg) high, intraglottal pressure (Pig) drops due to changing shape of the space between the glottis Plus “other” aerodynamic effects Pig < Pme Vocal fold returns to midline Utg = 0 Pattern repeats 100-200 times a second Vocal Fold Oscillation SPPA 6400 Voice Disorders: Tasko Complexity of vocal fold vibration Vertical phase difference Longitudinal phase difference The Glottal Cycle Phonation is actually quasi-periodic • Complex Periodic – vocal fold oscillation • Aperiodic – Broad frequency noise embedded in signal – Non-periodic vocal fold oscillation – Asymmetry of vocal fold oscillation – Air turbulence • Voicing vs. whispering Instantaneous sound pressure Sound pressure wave Time Characterizing Vocal Fold Vibration • Fundamental Frequency • Amplitude • Waveform Features SPPA 6400 Voice Disorders: Tasko Fundamental Frequency (F0) What factors dictate the vibratory frequency of the vocal folds? • Anatomical factors Males ↑ VF mass and length = ↓ Fo Females ↓ VF mass and length = ↑ Fo • Subglottal pressure adjustment – show example ↑ Psg = ↑ Fo • Laryngeal and vocal fold adjustments ↑ CT activity = ↑ Fo TA activity = ↑ Fo or ↓ Fo • Extralaryngeal adjustments ↑ height of larynx = ↑ Fo Amplitude • Subglottal pressure adjustment ↑ Psg = ↑ sound pressure • Laryngeal and vocal fold adjustments ↑ medial compression = ↑ sound pressure • Supralaryngeal adjustments – Optimizing sound radiation from vocal tract Waveform Features For example, • Waveform “shape” • Periodic vs. aperiodic energy components Waveform Shape: Spectral Tilt Waveform Shape: Spectral Tilt Pressed Breathy Waveform Shape: Periodic vs. Aperiodic SPPA 6400 Voice Disorders: Tasko Voice Production: Role of Resonation From Titze (1994)