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9/3/19 CSD 101 Chapter 3: Overview of the Anatomy and Physiology of the Speech Production Mechanism    

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Speech Production is Complex Anatomy: study of structures of the body and relationship of the structures Physiology: study of the functions or organisms and bodily structures Three Physiological Subsystems o Respiratory: driving force for speech via positive air pressure beneath the vocal folds o Laryngeal/Phonatory: vocal folds vibrate at high speeds o Articulatory/Resonatory: an acoustic filter that allows certain frequencies to pass while blocking other Primary Biological Functions o Supply oxygen to the blood o Remove excess carbon dioxide Structures of the Respiratory System o Pulmonary apparatus  Lungs: pair of air-filled elastic sacs that change in size and shape and allow us to breathe  Trachea: air moves into the lungs via the trachea and branches into bronchi  Pulmonary airways  Chest wall (thorax)  Rib cage  Abdominal content  Diaphragm Muscles of the Respiratory System o Inspiratory muscles: generally above the diaphragm o Expiratory muscles: generally below the diaphragm o Muscles of Inspiration  Diaphragm  Principle of inspiration  Dome-shaped structure composed of a thin, flat, nonelastic central tendon and broad rim of muscle fibers that radiate to the edges of the central tendon  Contracts during inspiration, pulling down and forward, increasing lung volume  Numerous thoracic and neck muscles also contribute o Muscles of Expiration

Most important muscles of expiration are located in the front and sides of the abdomen  Assist the diaphragm’s movement back to its relaxed, domeshaped  Other muscles may be used depending on body position, pathological state, and environmental conditions The Respiratory System o The Physiology of Tidal Breathing and Speech Breathing  Resting tidal breathing: breathing to sustain life  Inspiration  Diaphragm contracts, rib cage and lungs expand, .ng volume increases, and alveolar pressure drops  Causes air to rush in and equalize with atmospheric pressure  Expiration  Decrease in the size of the rib cage wall, comprehension of the lungs, increase in pressure in the lungs, air rushes out to achieve equilibrium with atmospheric pressure  Does not require active muscle contraction  A respiratory cycle is one inhalation and one exhalation  Resting Tidal Breathing  Duration of inspiration and expiration is relatively equal  Speech Breathing  Contraction of diaphragm leads to rapid, forceful inspirations  Inspirations are much shorter than expirations  The amount of air inspired is greater than during resting tidal breathing  Inspiratory and expiratory muscles are both activated during speech Lifespan Issues of the Respiratory System o Resting tidal breathing rate decreases from birth to adulthood  More alveoli o Maximum lung capacity is reached in early adulthood  Constant until middle age o Respiratory function is affected by exercise, health, and smoking Laryngeal System o Primary biological function of the larynx  Prevent foreign objects from entering the trachea and lungs o Larynx can impound air for forceful expulsion for foreign objects threatening lower airways o Structures of the Laryngeal System  Larynx 

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Air valve composed of cartilages, muscles, and other tissue Main sound generator for speech Sits on top of trachea and opens into the pharynx Appears to be suspended from the hyoid bone, the point of attachment for laryngeal and tongue muscles  Thyroid Cartilage  Largest laryngeal cartilage  Forms the front and sides of the laryngeal skeleton and protects the inner components of the larynx  Thyroid Prominence  “Adam’s apple”  Just below the thyroid notch  Vocal Folds  Attached at the front near the midline of the thyroid cartilage and at the back to the arytenoid cartilage via the vocal ligament  Abduct during respiration and adduct during phonation  Glottis  The space between the vocal folds o Muscles of the Larynx  Thyroarytenoid Muscle  Bulk of each fold  Contraction shortens and thickens the vocal folds  Cricoarytenoid Muscle  Stiffens and lengthens the vocal folds, increases pitch  Lateral Cricoarytenoid and Arytenoid Muscles  Contraction results in vocal fold adduction  Posterior Cricoarytenoid Muscle  Primary muscle of vocal fold abduction Lifespan Issues of the Laryngeal System o Larynx is small and high in the neck in newborns o Reaches final position between 10 and 20 years of age o Laryngeal cartilages increase in size and become less pliable o Vocal folds increase in length differentially for males and females  29 mm for males and 21 mm for females o Female laryngeal cartilage never completely ossifies o Vocal folds atrophy and lose elasticity with age o Men notice increase in pitch with advancing age o Women experience decreased pitch with the contribution of hormone related changes The Articulatory/Resonating System o Composed of    

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 Oral cavity  Nasal cavity  Pharyngeal cavity o Vocal tract is a resonant acoustic tube (musical instrument)  Shapes sound energy produced by respiratory and laryngeal systems into speech sounds o Structures of the Articulatory/Resonating System  Join, touch, connect biological functions  Change length of vocal folds to change sounds  Energy source is breath which vibrates  22 bones in the facial skeleton and cranium  Mandible articulates with the temporal bone by the temporomandibular joint  Teeth  Adults have 32 teeth within alveolar processes (ridge or bump behind the teeth) of the mandible and maxilla  Hard palate is composed of the horizontal bones of the maxilla  Tongue  Muscular hydrostat  Structural support through contraction of muscles and has a soft skeleton of connective tissue  Velum  Soft palate  Located in the pharynx  Uvula: termination of the velum (hangs down like a punching bag)  Velopharyngeal closure o Contact of the velum with the lateral and posterior pharyngeal walls (it elevates to close the nose off from the mouth)  Velar elevation o Necessary to prevent air or food escaping through the nose o Necessary to build up air pressure for production of pressure sounds (oral pressure) o Air that escapes through the nose during speech results in a nasal quality (hypernasal- can’t close the velum) Lifespan Issues of the Articulatory/Resonating System o Bones of the skull reach adult size by about age 8 o Newborns have 45 separate skull bones that fuse into 22 at adulthood

Lower facial bones reach adult size at about 18 years Definition emerges at about 6 months and is complete around 3 years Secondary definition is complete around 18 years A newborn’s tongue occupies most of the oral cavity Tongue reaches adult size by about 16 years of age By 2 months of age, infants can inconsistently close the velopharynx for syllable productions  Consistent between 6 months and 3 years o Aging has minimal impact on velopharyngeal function for speech o Length and volume of oral cavity increases  Influences the overall resonant characteristics  Lowers the frequencies at which the vocal tract naturally resonates The Speech Production Process o Begins with Phonation: vibration, opening and closing of the vocal folds o Air pressure builds up beneath adducted (closed) vocal folds (alveolar pressure) o Air pressure from below displaces the lower edges of each vocal fold laterally  Followed by lateral displacement of the upper edges o Elastic properties result in vocal fold vibration per second o Fundamental frequency: number of cycles of vocal fold vibration per second o Harmonics: whole number multiples of the fundamental frequency o Movement of the tongue, lips, and larynx change the shape of the vocal tract and modify sound o o o o o o

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