1. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Speech Science Primer Chapter 3: The Raw Materials—Neurology & Respiration

2. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Neurology

3. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Neuromotor events in speech production

4. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Basic divisions of nervous system Central nervous system (CNS): Brain and spinal cord Peripheral nervous system (PNS): All other components, including: –Cranial nerves (exit CNS from brainstem) –Spinal nerves (exit CNS from spinal cord) Efferent neurons: Nerve impulses from CNS to peripheral parts of the body (motor functions) Afferent neurons: Nerve impulses from peripheral parts of the body to CNS (sensory functions)

5. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Basic divisions of the brain Brainstem: Atop spinal cord –Upper brainstem includes thalamus, basal ganglia –Lower brainstem includes pons and medulla oblongata Cerebellum: Posterior to brainstem Cerebral hemispheres: Wrap around the brainstem; include areas for higher cognitive function and language

6. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Anatomy & physiology of neurons Individual neurons contain a cell body plus projections (dendrites, axons) Axons carry information away from the cell body (efferent) Dendrites receive information from incoming axons Firing is “all or nothing”: Stimuli above threshold always generate same response strength Stronger signals yield more frequent firing (amplitude doesn't change)

7. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Neuronal firing: The action potential Neuron at rest: –Has negative internal charge Neuron during firing: –Potassium (K+) exits the neuron –Sodium (Na+) floods into the neuron –Cell interior briefly gains positive charge Resting negative potential (charge) restored soon after firing

8. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins The synapse At the synapse, the axons of adjacent neurons branch into terminal arbors The terminal arbors meet the dendrites of the nerve cell receiving incoming stimulation Neuronal firing releases chemicals (neurotransmitters) into synaptic cleft Neurotransmitters can either facilitate or inhibit firing in the next neuron(s)

9. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Neurons at the synapse

10. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Speech & the CNS Cortical damage may yield speech or language problems: –Aphasia: Language impairment –Apraxia of speech: Deficits in speech motor programming –Dysarthria: Difficulty with speech movements Language and speech mainly controlled by left cerebral hemisphere: –Broca's area: Third convolution of left frontal lobe –Wernicke's area: First convolution of left temporal lobe

11. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Motor & sensory areas of the cortex Motor strip: Frontal lobe Sensory strip: Parietal lobe Sensory and motor strips separated by Fissure of Rolando Representation of the body is upside down in motor and sensory strips Large amounts of cortex are devoted to the hands and oral (speech) structures

12. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Motor strip

13. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Cortical areas for speech & language

14. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins More on laterality Wada testing: –Used to test for laterality prior to brain surgery –Paralyzes one side of the brain and the side of the body it controls (contralateral) Language laterality and handedness: –Right-handers: About 96% are left-lateralized for language –Left-handers: About 70% are left-lateralized for language –Some speakers show bilateral organization for language

15. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins "You've hissed my mystery lectures" Spoonerisms: Units of speech/language are exchanged in production (“damp towel” becomes “tamp dowel”) Errors follow rules: –Consonants only exchange with consonants –Vowels only exchange with vowels –First sounds and syllables are most prone to reversals Provide evidence that speech is not programmed one word, syllable, or sound at a time

16. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Speech & the peripheral nervous system Oral and laryngeal structures are innervated mainly by cranial nerves The respiratory system is innervated by spinal nerves Efferent impulses interface with muscles in motor units: –An action potential at the motor unit stimulates muscle fibers –Muscle contraction may cause movement of speech structures/articulators or change in muscle tone

17. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Respiration

18. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Respiration & speech All English speech sounds require airflow from the lungs Airflow forces the vocal folds to vibrate in voiced sounds (phonation) Obstructing airflow in the upper vocal tract yields supraglottal sound sources (e.g., bursts, frication noise), especially for consonants

19. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Respiratory system as power supply

20. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Physics of breathing Expansion of the chest and lungs creates negative pressure (Boyle's law) Air flows in to equalize the pressure (inhalation) Contraction of the chest and lungs creates positive pressure Air flows out (exhalation) Exhaled airflow is modified for speech production

21. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Support structure of respiratory system Vertebral column Sternum Ribs: –Join to vertebral column at back (bony connections) –Upper ribs join sternum at front via cartilage –Lower (floating) ribs connect to vertebrae only

22. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Structure of thoracic cavity Encircled by bone (ribs, sternum, vertebrae) Diaphragm forms floor of the thoracic cavity Pleural linkage connects lungs to rib cage and diaphragm: –Costal (rib) pleura lines rib cage –Pulmonary (visceral) pleura surrounds lungs –Fluid holds the pleural layers together but allows sliding movement –The lungs respond to the expansion and contraction of the rib cage and diaphragm movements

23. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins External intercostal muscles Superficial to internal intercostal muscles Connect osseous portions of ribs to each other Run downward toward sternum Contraction raises and expands rib cage: Inhalation

24. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Internal intercostal muscles Deep to external intercostal muscles Run downward away from sternum Connect both osseous and cartilaginous portions of ribs: –Interosseous portions: Lower and compress rib cage: Exhalation –Interchondral portions: Raise and expand rib cage: Inhalation

25. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Inhalation in quiet breathing The medulla oblongata sends commands to the respiratory muscles The diaphragm contracts: –The thoracic cavity expands vertically downward The external intercostals, interchondral portions of internal intercostals, contract: –The thoracic cavity expands up and out Lung volume increases because of pleural linkage Air pressure within the lungs decreases Air flows in through the nose and mouth

26. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Speech breathing: Overview More air is typically inhaled than in quiet breathing (especially for loud or long utterances) Accessory muscles of neck, chest, abdomen, and back may assist in expanding rib cage Control is more voluntary and conscious than in quiet breathing Exhalation is slower and takes up more of the respiratory cycle

27. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Passive expiration in quiet breathing Relaxation of the respiratory muscles with air in the lungs: –Allows the lungs and rib cage to recoil –Respiratory system collapses –Air pressure within the lungs increases –Air flows out –Lungs return to resting volume

28. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Respiratory quantities Tidal volume: Amount of air exchanged (in and out) during a cycle of quiet breathing Vital capacity (VC): Amount of air exchanged in maximum inspiration-maximum expiration: –Respiratory volumes often expressed as a percentage of VC (e.g., tidal volume is about 10% of VC) Resting volume: The respiratory system relaxes at about 40% of VC

29. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Respiratory volumes

30. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Active expiration (speech & singing) Above resting volume: –Muscles counteract passive collapse of lungs –Inspiratory muscles maintain lungs in expanded state –Slow expiration early during exhalation phase Below resting volume: –Muscles force respiratory system into compressed state –Expiratory muscles compress thorax and abdomen –Maintain expiration longer

31. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Muscle use in speech breathing

32. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Details of muscle activation for speech During breathing, both inspiratory and expiratory muscles are active most of the time The balance between inspiratory and expiratory muscle action changes continuously The respiratory system maintains fairly constant pressure during speech Small variations occur to change intensity (e.g., for stressed syllables)

33. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins The respiratory system & syllable stress Increasing subglottal pressure (Ps) yields an increase in intensity (I): –I = Ps 3 or Ps 4 –Small increases in Ps cause large increases in I Abdominal and internal intercostal muscles probably raise Ps for stressed syllables Higher Ps may contribute to other features of syllabic stress: –Higher f 0 –Increased duration

34. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Speech breathing & phrasing Inspirations usually occur at major linguistic boundaries (phrases, sentences) Long utterances require muscle control to maintain subglottal pressure (Ps) throughout Utterance requirements affect both inspiratory and expiratory muscle use

35. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins Respiratory control in clinical populations Voice disorders: Improper laryngeal valving may waste exhaled air Hearing impairment: Poor laryngeal control may again waste air Motor speech disorders: May affect respiratory muscle coordination