Introduction to Communication Disorders: A Lifespan Evidence-Based Perspective 5th Edition

CHAPTER 3: Overview of the Anatomy and Physiology of the Speech Production Mechanism Introduction to Communication Disorders: A Lifespan Evidence-Based Perspective 5th Edition Owens, Farinella, & Metz Developed by Sarah A. Dachtyl, Ph.D., CCC/SLP Chapter Learning Goals List and describe the structures of the respiratory, laryngeal, and articulatory/resonating systems Explain the respiratory processes for quiet breathing and for speech breathing Briefly describe the speech production process Explain the articulatory and resonating processes for human speech Outline The Physiological Subsystems Supporting Speech The Speech Production Process The Physiological Subsystems Supporting Speech Anatomy The study of the structures of the body and the relationship of these structures to one another Physiology The study of the functions of organisms and bodily structures The Physiological Subsystems Supporting Speech Three physiological subsystems for speech Respiratory system: The driving force for speech Phonatory system: Anatomical structures vibrate, setting air molecules in the vocal tract into multiple frequencies of vibration Articulatory/resonating system: An acoustic filter that allows certain frequencies to pass while blocking other frequencies The Physiological Subsystems Supporting Speech The Respiratory System Primary biological functions: Supply oxygen to the blood and remove excess carbon dioxide Also serves as the generating source for speech Structures Pulmonary apparatus: Lungs, trachea, pulmonary airways Chest wall (thorax): Rib cage, abdominal wall, abdominal content, diaphragm The Physiological Subsystems Supporting Speech Muscles of the Respiratory System Inspiratory Muscles Diaphragm: Contracts during inspiration, pulling down and forward, increasing lung volume Also numerous thoracic and neck muscles Muscles of Expiration Generally below diaphragm Most important muscles are located in the front and on the sides of the abdomen Assist diaphragm’s movement back to its relaxed position Other muscles may be used depending on body position, pathological states, and environmental conditions The Physiological Subsystems Supporting Speech Physiology of Tidal Breathing and Speech Breathing Resting Tidal Breathing Breathing to sustain life Inspiration: Diaphragm contracts, rib cage and lungs expand, lung volume increases and alveolar pressure drops, air rushes in Expiration: Rib cage wall size decreases, lungs compressed, pressure within lungs increases, causing air to rush out Speech Breathing Inspiration: Rapid, greater amount of air Expiration: Much longer than inspiration Inspiratory and expiratory muscles activated during speech The Physiological Subsystems Supporting Speech Lifespan Issues of the Respiratory System Resting tidal breathing rate decreased from birth to adulthood More alveoli Maximum lung capacity reached in early adulthood Remains constant until middle age Respiratory function affected by exercise, health, and smoking The Physiological Subsystems Supporting Speech The Phonatory System Larynx Air valve composed of cartilages, muscle, & other tissue Main sound generator for speech production Sits on top of the trachea and opens up into the pharynx Appears to be suspended from the hyoid bone Primary biological function is to prevent foreign objects from entering the trachea and lungs Consists of the thyroid, arytenoid, and cricoid cartilages, attached via ligaments and membranes The Physiological Subsystems Supporting Speech The Vocal Folds Front attachment: Midline of the thyroid cartilage Back attachment: Arytenoid cartilages via the vocal ligament Appear to be ivory bands of tissue Abduct during respiration and adduct during phonation The Physiological Subsystems Supporting Speech Lifespan Issues of the Phonatory System Newborns: Larynx is small and high in the neck Larynx reaches final position 10-20 years of age Laryngeal cartilages become less pliable with age Vocal folds increase in length differentially for males and females Female laryngeal tissue never completely ossifies Vocal folds atrophy There is increased pitch in men and decreased pitch in women The Physiological Subsystems Supporting Speech The Articulatory/Resonating System Composed of oral cavity, nasal cavity, pharyngeal cavity (vocal tract) Vocal tract: Acoustic tube that shapes sound energy produced by respiratory and laryngeal systems into speech sounds The Physiological Subsystems Supporting Speech Structures of the Articulatory/Resonating System Facial skeleton and cranium (22 bones) Mandible articulates with the temporal bone by the temporomandibular joint Teeth Tongue Velum (soft palate) Uvula Velopharyngeal closure: Contact with the velum and the lateral and posterior pharyngeal walls Necessary to prevent air/food escaping through the nose and to build air pressure for pressure sounds Nasal quality if air escapes The Physiological Subsystems Supporting Speech Lifespan Issues of the Articulatory/Resonating System Bones of the skull reach adult size by 8 years Newborns have 45 separate skull bones that fuse into 22 at adulthood Lower facial bones reach adult size at 18 years Dentition emerges around 6 mos and is complete around 3 yrs Secondary dentition complete around 18 years Newborn’s tongue occupies most of the oral cavity Tongue reaches adult size around 16 years Consistent velopharyngeal closure occurs between 6 mos and 3 yrs Length and volume of the oral cavity increases throughout development The Speech Production Process Begins with phonation Tracheal/alveolar pressure builds up beneath adducted vocal folds Elastic properties result in vocal folds colliding, closing off the airway Fundamental frequency: Number of cycles per second Harmonics: Whole-number multiples of the F0 Movement of the tongue, lips, and larynx change the shape of the vocal tract and modify sound Summary Although anatomy is static, these structures are capable of dynamic movement that can result in the unique human process of speech. Knowledge and understanding of this information is important for evaluation and treatment of communication disorders that are a result of breakdown in these systems. Online Resources Praat: www.praat.org Animated anatomical images of the three major body planes: http://www.madsci.org/~lynn/VH/ Respiratory anatomy: http://www.getbodysmart.com/ap/respiratorysystem/menu/menu.html Head and neck anatomy: http://www.instantanatomy.net/headneck.html