Physiology of Articulation and Resonance

Cineradiography

• Uses X-rays to record moving images of speech production. 

• Shows movement and positioning of the tongue, jaw, lips, and other vocal tract structures. 

• Allows visualization of articulators during speech. 

• Involves radiation exposure. 

MRI (Magnetic Resonance Imaging)

• Uses magnetic fields and radio waves to create images. 

• Shows soft tissue structures of the vocal tract. 

• Can show tongue shape and position during speech. 

• Does not use radiation. 

Ultrasound

• Uses high-frequency sound waves to create images. 

• A probe is placed under the chin. 

• Shows tongue shape and movement during speech. 

• Particularly useful for observing tongue movement. 

Electropalatography

• Uses a custom-made artificial palate containing electrodes. 

• Detects where and when the tongue makes contact with the hard palate. 

• Displays tongue-to-palate contact patterns. 

• Useful for evaluating tongue placement during consonant production. 

Acoustic measures

• Uses computer analysis of recorded speech sounds. 

• Measures the acoustic properties of speech. 

• Can examine frequency, duration, intensity, and voice characteristics. 

• Often uses spectrograms and waveforms.

How long is Vocal Tract Length at birth?

6-8 cm

Growth pattern of the Vocal Tract:

• Rapid change 0-24 months 

• Steady development until 7 y.o. 

• Final phase of development: 10-18 y.o. 

Proportional changes in Vocal Tract:

• Larynx is high up in neck of infant, adults it is more removed from oral cavity 

• Epiglottis provides progressively less protection from penetration 

• Tongue descends into floor of mandible as mandible grows 

Movements of babies in utero:

• Sensorimotor development & learning, development of reflexes, development of a&p 

• Begins with spontaneous startles & gentle movement (7-8 weeks) 

• Sequenced movement of body parts begin after 

Movements of newborns:

• Rooting reflex, suck reflex, grasp reflex 

• Reflexes needed for sustenance and motor development 

• Movements ore poor controlled, gross, responsive to environment/needs

Movements of infants:

• Begins to develop control of motor functions 

• Voluntary movements of truck, neck, and limbs 

• Gains purposeful control of motor patterns 

• Ability to make graded movements of mandible 

• Differentiated tongue movement 

Movements of children:

• Gross movements before fine movements 

• Head, neck, trunk control before mandible and tongue control 

• Increased ability to make quick readjustments of articulators (necessary for speech)

Emergence of Articulation:

Child heard producing certain phonemes but still inconsistent, muscle movements are not yet coordinated

Mastery of Articulation:

Child consistently producing target phonemes, movements coordinated & well-controlled, motor (procedural) memory has formed

Thought to Speech:

Conceptual system -> Phonological system -> Motor execution

*at each stage there is a feedback system that allows you to correct mistakes BEFORE speak then once spoken you can also self-correct

Serial order of speech (theories must account):

speech occurs as a sequence unfolding in time (phonemes, syllables, words, pauses, stress, etc.)

Degrees of freedom (theories must account):

complex system of many different muscle groups requiring precise spatio-temporal coordination

Motor equivalence (theories must account):

many ways to achieve same target production. No motor invariance (ex: talking with mint/cigarette in mouth)

Context sensitivity (theories must account):

speech movements change with context: coarticulation, rate, stress, articulatory precision

Apraxia of Speech:

• Disorder of motor planning, impaired premotor cortex and insula (muscle strength is unaffected, signals from motor cortex to muscles may be relatively unaffected) 

• Addition, deletion, substitution, ordering of phonemes 

• Oral groping, errors are inconsistent/variable 

Dysarthria:

• Impaired neuromuscular execution of speech 

• Ataxic, flaccid, hypokinetic, hyperkinetic, spastic, mixed 

Ataxic

• Damage: Cerebellum or cerebellar pathways. 

• Characteristics: Poor coordination of speech muscles; irregular speech rhythm, stress, and timing. 

• Key clue: Sounds like uncoordinated, “drunken” speech. 

Flaccid

• Damage: Lower motor neurons (LMNs), cranial nerves, or neuromuscular junction. 

• Characteristics: Weakness, reduced muscle tone, breathy voice, hypernasality, and imprecise articulation. 

• Key clue: Muscle weakness or paralysis. 

Hypokinetic 

• Damage: Basal ganglia (especially substantia nigra); commonly associated with Parkinson's disease. 

• Characteristics: Reduced movement, reduced vocal loudness, monotone voice, and short rushes of speech. 

• Key clue: Too little movement. 

Hyperkinetic

• Damage: Basal ganglia control circuits. 

• Characteristics: Involuntary, excessive movements that interrupt speech; irregular changes in voice, pitch, and articulation. 

• Key clue: Too much or uncontrolled movement. 

Spastic

• Damage: Bilateral upper motor neuron (UMN) pathways. 

• Characteristics: Increased muscle tone, muscle stiffness, strained/strangled voice, and slow speech. 

• Key clue: Tight, stiff muscles. 

Mixed

• Damage: Multiple motor systems or pathways. 

• Characteristics: Combination of characteristics from two or more types of dysarthria; depends on which systems are damaged. 

• Key clue: Symptoms of multiple dysarthrias (e.g., spastic-flaccid).