Physiology of voice and degulitition

1. PHYSIOLOGY OF PHONATION
AND DEGULITITION
PRESENTER – DR SHWETA SHARMA
MODERATOR – DR KANWAR SEN

3. Intiation of voiceIntiation of voice
Prephonatory inspiratory phase
Exhalation of pulmonic air ( excitor )
Subglottic pressure increases
Crossing Phonation threshold pressure
And overcoming glottal resistance

4. Review of anatomy

5. Intrinsic Muscles of larynxIntrinsic Muscles of larynx
• AdductorsAdductors – vocal folds are together
• AbductorsAbductors – vocal folds apart
• Tensors -Tensors - Stiffen

6. AA
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7. AA
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9. Starting and maintaining phonation
• Adduction: vocal processes of arytenoids
moved together (lateral cricoarytenoid,
interarytenoid muscles)
• This brings the vocal folds together, thus
closing the glottis
Front view Rear view Side view from above

11. A
b
d
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12. No phonation, or stopping
phonation
• Abduction: Vocal processes of arytenoids
(front part) rotated backwards and
outwards (posterior cricoarytenoid
muscle)
• This moves the vocal folds apart and so
widens the glottis
Front view Rear view Side view from above

13. • External Thyroarytenoid
– Relaxor, shortensRelaxor, shortens
and adductsand adducts
• Internal Thyroarytenoid
– Tensor, shortens andTensor, shortens and
stiffensstiffens
Cricothyroid Muscles –
Tensor, lengthens andTensor, lengthens and
stiffensstiffens

15. CONTROL MECHANISMS

16. Myo-Elastic Aero DynamicMyo-Elastic Aero Dynamic
TheoryTheory
1. Fundamental frequency
• Vocal folds – mass & viscoelasticity
• Subglottal pressure
2. Bernoulli’s principle

17. Bernoulli’s principle
• An increase in velocity results in a drop in
the pressure exerted by the molecules of
moving particle, the pressure drops being
perpendicular the direction of the flow

18. Schematic showing the Bernoulli Effect. The arrows indicate movement of pressure. As the air
moves through a narrowing, inside pressure drops and outside pressure increases pulling the sides
inward.
In relation to vocal tract MARANMARAN describes it as follows, “ when air passes from
large space to another (e.g. from lung to pharynx, through constriction (the
glottis), the velocity is greatest and the pressure is least at site of constriction.
The resulting negative pressure in the glottis, caused by bernoulli’s effect results in the
vocal folds closing rapidly as they are sucked together, the inferior vocal fold margin
closing first.

19. BODY COVER THEORYBODY COVER THEORY
• MORPHOLOGICAL
STRUCTURE
• COVER
• BODY
• COUPLING
• Muscles

20. MUCOSAL WAVE PATTTERNMUCOSAL WAVE PATTTERN
Dynamics of vocal fold
• Closing phase more
rapid than opening
• Four phases
• Articulator??
• Normal phonation
can occur when
there is incomplete
closure *

23. LINEAR VERSUS NONLINEAR
APPROACH
• LINEAR
• NONLINEAR --- multiple variables

24. BOMECHANICAL PROPERTIES
OF VOCAL FOLDS
• MASS
– Cricothyroid
– Thyroarytenoid
• STIFFNESS
– Coupling
• VISCOSITY

25. SUPRAGLOTTAL RESONANCE
• Modifying the acoustic output of the glottis
• Higher fundamental frequency is more
susceptible to energy loss in supraglottal
vocal tract.

26. PHONATORY OUTPUT
• INTENSITY
– Relative loudness = sound pressure level
– All three levels regulation
• Subglottal – pressure (low frequencies) and airflow (high
frequencies)
• Glottal apmlitude of vocal fold = tension & glottal
configuration
– Size of glottis positvely related to transglottal pressure,
Constriced glottis  lower transglottal pressure energy
conversion better
– Ideally Vocal fold viscosity minimum
• supraglottal

27. • FUNDAMANTAL FREQUECNCY
– Correlates vocal fold tension & sublottal
pressure
– Mainly cricothyroid

28. Pitch control
• Increasing pitch: contracting cricothyroid muscle:
pulls front of cricoid up towards thyroid, so back of
cricoid moves down and back, taking arytenoids
with it and stretching/tensing vfs → vibrate faster
• vocalis – shortens/thickens & tenses vocal folds
Front view Rear view Side view from above

29. Pitch control
• Increasing pitch: contracting cricothyroid muscle:
pulls front of cricoid up towards thyroid, so back of
cricoid moves down and back, taking arytenoids
with it and stretching/tensing vfs → vibrate faster
• vocalis – shortens/thickens and tenses vocal folds
(complex adjustments to length, tension, thickness & medial compression)
Front view Rear view Side view from above

30. • PHONATION MODES
– Different characteristics of phonation
associated with a class of vocal fold vibratory
patterns.
– VOCAL REGISTERS
• Distinct regions of vocal quality over certain ranges
of pitch and loudness

31. REGISTERSREGISTERS EQUVALENTEQUVALENT
TERMSTERMS
VOCAL FOLDSVOCAL FOLDS FREQUENCYFREQUENCY
RANGE (Hz)RANGE (Hz)
LOFT REGISTER
Highest vocal
frequencies
FALSETTO Short or no closed
phase. Thin,
tense, lengthened.
Minimal vibration
275-1100
MODAL REGISTER
Range of
fundamental
frequencies most
commonly used in
speaking and singing
CHEST,
HEAD,
MIDDLE,
HEAVY VOICE
Complete
adduction
100-300
PULSE REGISTER
Lowest range of
vocal frequencies :
laryngeal output is
percieved as
pulsatile
VOCAL FRY,
GLOTTAL
FRY, CREAKY
VOICE
Long closed
phase
20-60

32. • EFFICIENCY AND ENDURANCE
– Ratio of acoustic output to the input
aerodynamic power
– Maximum phonation time
– S/Z ratio voiceless to voiced

34. STRUCTURES INVOLVED IN
SWALLOWING

35. Review of anatomy

37. Tongue

38. Pharynx

40. Sequence of events in the normal
swallow

41. Oral phase : food reduced and bolus prepared
Bolus moved to posterior part of tongue
Bolus contacts the trigger points in
oropharynx & pharyngeal phase
intiated
Pharyngeal phase : bolus moved
past closed larynx
Oesophageal phase : bolus enters oesophagus
*** other strructures ***

42. Russell et al. estimated healthy oeophageal transit time to less than
15 seconds with a mean of 7 to 8 seconds

45. Oral Phase
• Oral preparatory phase = bolus formation

46. • Sequence of events initiated to ensure
protection of airway
• Trigger points
• “Premature spillage”
• Reflex closure of glottis is intiated and apnea
onset occurs approx. 0.19 seconds prior to
elevation of larynx
• Movement of epiglottis : active or passive??
Pharyngeal Phase

47. • Opening of the glottis at the very end of
the oropharyngeal swallow sequence is
part of the airway protection
Oesophageal Phase

48. Respiration and swallowing
• Individual pattern
• Swallow apnea
– Cessation of respiration during pharyngeay
transit
– Less than 1 second ~ bolus volume &
consistency
• Expiration occurs in 100-80% of healthy
swallow***

49. Infant vs. Adult

50. Infant vs. Adult

51. Neural control
Voluntary initiation Passive initiation
(presence of food, liquid or
accumulation of saliva)
Prefrontal, frontal and parietal Several regions especially the
one anterior to the face region of
the precentral gyrus (broadman’s
area 6)

53. On transcranial magnetic stimulation of
frontal swallowing centre
1. Lower precentral gyrus and posterior inferior
frontal gyrus control oral phase of swallowing
2. Pharyngeal and oesophageal phase of
swallowing are controlled from more
rostromedial regions of the cortex within
anterior inferior and middle frontal gyri
3. Swallowing problems after stroke

54. 4. Other areas included frontal operculum,
orbitofrontal cortex and insula
5. Coordination ~ within medulla ( coming via
corticobilbar tracts )
6. Mechanoreceptors ~ Afferent from Nucleus
tractus solitarius & spinal trigeminal nucleus
7. Efferent
• Nucleus ambiguus (vagus) ~ palate, pharynx,
larynx
• Hypoglossal nucleus ~tongue
• Trigeminal and facial ~ jaw & lips
• Cervical spinal cord (c1,c2,c3) ~infrahyoid group

55. Two main neurons for coordination and
regulaton = LATERAL & MEDIAL
MEDULLARY SWALLOWING CENTRES
. Dorsal region of
medulla above
Convergence of
sensory input
 sequencing
of swallowing
2. Ventrally
around
Outputs the
various
cranial nerve
nuclei

56. Thank you