PHYSIOLOGY OF

PHONATION AND INV OF

HOARSENESS OF VOICE

Dr R Anbuchezhian

PHONATION

Physical act of sound

production in larynx by vocal
cords
vibrating
in
an
expiratory blast of air.

PROPERTIES OF SOUND

SOUND

INTENSITY

FREQUENCY

TIMBRE

RESONANCE

VOICE PRODUCTION BY LARYNX

Respiratory bellows

Vibratory mechanism

Resonating chambers

THEORIES OF PHONATION
I.

NEUROMUSCULAR THEORY

II.

AERODYNAMIC THEORY

III.

COVER/BODY THEORY

NEUROCHRONAXIC THEORY OF HUSSON, 1953

Neuromuscular theory, Clonic theory

By Husson 1953

Postulated that the vibration of vocal cords

are direct result of active contraction of
thyroarytenoid and independent of the air
stream.
Claimed that thyroarytenoid has special
transverse muscle fibres that cause abduction
of vocal cord.
For the production of sound of any frequency,
the transverse fibres of thyroarytenoid muscle

EVIDENCE REFUTING NEUROMUSCULAR THEORY

Failure to confirm the presence of transverse fibres in

thyroarytenoid.

Claimed transverse fibres may not achieve the

observed amplitude of vibration of vocal cords.

Vocal range 82-1175 Hz (max 44 2058 Hz)

Stimulus beyond 100/sec cause tetany.

VC movements measured by cinematography in

tracheotomized individuals

AERODYNAMIC THEORY
Myo elastic theory/ Tonic theory
Van den Berg in 1958
Classic and still the most accepted theory
Postulates that effective force setting the VC in
vibration is the infraglottic air column.
Opening and closing of the VC are passive result
of raised pressure of air stream passing through,
while the tonically contracted VC muscles
maintains the apposition.

EVIDENCE FOR AERODYNAMIV

THEORY

Models, Artificial larynx produces sound

Cadaveric larynx produced the sound, varying the tension

varied the pitch.

Increase the pressure in abdomen increased the intensity

and to some extent, pitch of the sound.

Effects of unilateral and bilateral vocal cord palsy can be

explained.

Production of the oesophageal speech after laryngectomy.

COVER/BODY THEORY

INITIATION OF VOICE & PHONATION

Prephonatory inspiratory phase

Phonation

VC Adduction
Pulmonic air exaled between adducted
vocal cords generating vocal fold
oscillations.

PHONATION THRESHOLD
PRESSURE
Air pressure required to begin
voicing( 2.5 mm H2O AT 75 db
APPROX)

VIBRATORY CYCLE
ADDUCTION

RECOIL

AERODYNAMIC
SEPARATION

FACTORS CAUSING VF TO RETURN TO MIDLINE

BERNOULLIS EFFECT.

ELASTIC FORCES IN VOCAL FOLDS

DECREASED PRESSURE

STAGES OF V C VIBRATION
Periods of V C Contact / lack
1.Closing
2. Closed
3. Opening

4. Open

Cover /Body Theory

Body Vocalis
Cover Mucous membrane
Undulating wave of
movement of mucous
membrane over the firm
vocalis muscle producing the
sound wave.

REGISTERS

Perceptually distinct regions of vocal quality over certain ranges of pitch and loudness.

Loft Register/Falsetto register

Modal
Pulse register

LOFT REGISTER/FALSETTO REGISTER

Highest frequency
Larynx raised
Pharynx shortened
Vocal fold extremely tense and thinned
Position adducted (almost)
Vibration minimal
F0 - 275 - 1100 hz

MODAL REGISTER

Speech and singing frequency

Larynx down
Pharynx normal
Vocal fold complete closure triangular
Position adducted
Vibration slowly and whole length
F0 - 100 - 300 hz

PULSE REGISTER/ GLOTTAL FRY

/ VOCAL FRY/ CREAKY VOICE

Lowest frequency/normal speech

Larynx normal
Pharynx normal
Vocal fold normal
Position adducted
F0 - 20 - 60 hz

VOICE AND SPEECH

PRODUCTION

VOICE SPEECH PRODUCTION

Vibration Of VC constitutes raw glottic

sound source.

This fundamental vibratory sound is

modified & resonated by rest of vocal cord
to produce recognizable voice quality.

Co ordination of phonatory & articulatory

behavior represent the most advanced
sensori motor system found in human body.

CHARACTERISTICS OF GLOTTIC SOUND

Quality
Frequency
Amplitude

CHARACTERISTICS OF GLOTTIC SOUND

QUALITY
FREQUENCY
AMPLITUDE

QUALITY
Quality depends on vibratory characteristics
of the laryngeal structures. Regularity of
waves
Breathy voice - Incomplete add with air leak
Hoarseness - irregular mucosal waveform
vibration
Whisper - insufficient VC adduction for vibration,
but sufficient to cause audible turbulent air
Strained voice - Strong adduction with inc
subglottal air pressure
Noise Aperiodic sound

CHARACTERISTICS OF GLOTTIC
SOUND

QUALITY
FREQUENCY
AMPLITUDE

FREQUENCY
Def : No of vibratory cycles per second
Frequency is proportional to length,
elasticity and tension
Jitters/pitch perturbation - short
term variance in the frequency of
vocal cord

CHARACTERISTICS OF GLOTTIC
SOUND

QUALITY
FREQUENCY
AMPLITUDE

AMPLITUDE
Def : Size of the oscillation of the vocal
fold.
Shimmers/amplitude perturbation
- short term variance in the intensity
of the vocal signal

PITCH CONTROL

CHANGES IN VOCAL FOLD

LENGTH & TENSION

CONTRACTION OF
THRYOARYTENOID
DECREASES PITCH

CONTRACTION OF
CRICOTHYROID
INCREASES PITCH

TENSION

SIZE & PHYSICAL

PROPERTIES OF LARYNX

CHILDREN HAVE SMALLER LARYNX

HIGHER PITCH

PUBERTY RAPID INCREASE IN LARYNX SIZE

- UNSTABLE PITCH CONTROL

OLD AGE LOSS OF ELASTICITY

- INCREASED PITCH

MODIFYING THE GLOTTIC

SIGNAL
Raw glottic signal is modified into speech by
Resonance
Articulation

VOCAL RESONANCE

SUPRALARYNGEAL TRACT ACTS AS THE

RESONATING CHAMBER.

LEADS TO PROLONGATION
- AMPLIFICATION
- FILTERING OF SOUND

VOCAL RESONANCE
Oral resonance
Degree of jaw mvmt, mouth opening,
tongue raising,
Pharyngeal constriction
Nasal resonance
Velopharyngeal spincter

ARTICULATION
Synchronised movements of the organs of articulation
(eg. Palate , tongue, lips, etc) to change glottal sound
into a recognisable speech.
DESCRIBED BY SOURCE FILTER MODEL

vowels)

Source

larynx

Filters

lips , tongue , palate , pharynx

( Form consonants and

VOWELS
These are sounds where there is no
Obsrtuction to flow of air as it passes from
larynx to lips
Eg : A, E, I, O, U

CONSONANTS
These are sounds where there is more
definitive obstruction to air
Eg : P, B, M, W, F, T, S, Z, R,
Different consonants are produced by :
- place of articulation
- Manner of articulation
- State of larynx

CONSONANTS
BILABIAL
LABIODENTAL
DENTAL
BASED ON PLACE
OF ARTICULATION

ALVEOLAR
PALATAL
VELAR
GLOTTAL

CONSONANTS BASED ON PLACE OF

ARTICULATION

BILABIAL
UPPER
AND
LOWER LIP
- P, B,
M,W

CONSONANTS BASED ON PLACE OF

ARTICULATION

LABIODENTA
L
-TOP TEETH
AND
LOWER LIP
-- F, V

CONSONANTS BASED ON PLACE OF

ARTICULATION

DENTAL
- TONGUE TIP
WITH
TOP TEETH
OCCLUSION
- th

CONSONANTS BASED ON PLACE OF

ARTICULATION

ALVEOLAR
-TONGUE TIP
TOUCHING
RIDGE
BEHIND TEETH
-- T, D, N, S, Z,
R, ch, dj

CONSONANTS BASED ON PLACE OF

ARTICULATION

PALATAL
-MIDDLE
TONGUE
WITH
HARD PALATE
- Y

CONSONANTS BASED ON PLACE OF

ARTICULATION

VELAR
-POSTR
TONGUE
AND
SOFT PALATE
- K, G, ng

CONSONANTS BASED ON MANNER OF

ARTICULATION

Plosives
: p, b, t, d,
k, g
Fricatives
: F, V, S, Z,
th
Affricatives
: ch, dj
NASAL
: M, N, ng
Approximant
: w, y, l, r,

Voice
Acoustic output from the vocal tract that
are characterised by their dependence
on the vocal fold vibratory inputs
Pathological phonation
Imbalance in normal ratio of periodic
sound and noice components of acoustic
signal resulting in poor voice quality

HOARSENESS
Hoarseness is described as
having difficulty producing
sound when trying to speak, or
a change in the pitch or quality
of the voice. The voice may
sound excessively breathy or
husky.
V

Workup

HOARSENESS
EVALUATION
OF
A
PATIENT
WITH
HOARSENESS INCLUDES THE FOLLOWING: - HISTORY
- PHYSICAL
EXAMINATION
- ANCILLARY TESTS

HISTORY
History
Infection
- laryngitis

Trauma

- Nerve paralysis

- Laryngeal fractures

- During Intubation

Arytenoids dislocation

Mucosal lacerations

- Granuloma

HISTORY
History
Pulmonary conditions
- COPD
- Asthma
Gastrointestinal
LPR
Autoimmune
- RA
Endocrine
- hypothyroidism (Edematous)
-Danazol in female (Irreversible enlargement of
larynx)

History
HISTORY
Surgical

history
- Skull base
procedures
- Thyroidectomies
- Aortic aneurysm repairs
Social history
- Tobacco
- Alcohol
- Talkativeness
Occupational history
- Voice abuse
Toxic exposures
- Pollutants, pollen grains, ethyl alcohol,
tobacco, allergies

HISTORY

Muscle Tension dysphonia

Stress, anxiety, depression, conversion disorder
Postural and breathing problems, poor vocal hygiene
Exposure to excessive environmental dust, smoke, fumes

Puberphonia / Mutational falsetto/ Adolescent transitional

voice disorder
Fundamental within female speaking range. (Never
broken)

Presbylaryngis

Age induced chages after 50 yrs

COMMON SYMPTOM SUGGESTIVE OF SPECIFIC DIAGNOSIS

LARYNGEAL EXAMINATION
- INDIRECT LARYNGOSCOPY
- FLEXIBLE LARYNGOSCOPY
- RIGID LARYNGOSCOPY

INDIRECT LARYNGOSCOPY
ADVANTAGES
QUICK
INEXPENSIVE
LITTLE EQUIPMENT
DISADVANTAGES
GAG
ANATOMIC
FEATURES
NONPHYSIOLOGIC

FLEXIBLE LARYNGOSCOPY
ADVANTAGES
WELL TOLERATED
COMPLETE
EXAMINATION
VIDEO
DOCUMENTATION
DISADVANTAGES
MORE TIME
EXPENSIVE

RIGID LARYNGOSCOPY
ADVANTAGES
BEST IMAGES
VIDEO
DOCUMENTATION
DISADVANTAGES
EXPENSIVE
NONPHYSIOLOGIC
GAG
REQ OF GA

VIDEOSTROBOSCOPY
Two Types
- Synchronous motionless
- Asynchronous slow motion
Carried out in the same way as IDL but light
source is flashing Xenon tube. The light source
is linked to Hopkins's rod or Fibrescope
Permits accurate visualization of epithelial
abnormalities which are missed out on IDL due
to fast vibrations
Video recording
Detailed review
Comparison after treatment

VIDEOSTROBOSCOPY
VOCAL FOLD CLOSURE PATTERN
VOCAL FOLD VIBRATORY PATTERN
MUCOSAL WAVE OF EACH VOCAL FOLD
SYMMETRY

VIDEOSTROBOSCOPY
ADVANTAGES: ALLOWS APPARENT SLOW MOTION
ASSESSMENT OF MUCOSAL VIBRATORY DYNAMICS, VIDEO
DOCUMENTATION
DISADVANTAGES: TIME CONSUMING, EXPENSIVE

V
3

PANENDOSCOPY
INDICATIONS
BIOPSY SUSPICIOUS LESION
LARYNGEAL CANCER - TUMOR EXTENT, SECOND
PRIMARY
HOARSE PATIENTS WITHOUT DIAGNOSIS AT END
OF WORKUP
PERSISTENT OR RECURRENT VOCAL SYMPTOMS
(MAY NEED TO REPEAT)
PATIENTS WITH PRIOR
ONSET HOARSENESS

CANCERS

WITH

NEW

OTHER TESTS
LABS: TSH, LFT
PLAIN FILMS: CXR, LAT NECK
CT SCAN :
MRI BA SWALLOW

LARYNGEAL
EMG
MYOPATHY NORMAL FREQUENCY OF
FIRING BUT DECREASED AMPLITUDE (A)
NEUROPATHY DECREASED FREQUENCY
BUT OCCASIONAL NORMAL AMPLITUDES(B)
POLYPHASIC REINNERVATION POTENTIALS
INDICATE SOME LOSS OF FUNCTION BUT
REINNERVATION HAS BEGUN

OTHER OBJECTIVE METHODS OF VOICE EVALUATION

Perceptual evaluation of voice
Process of assessing and grading the severity of
voice disorder in a speakers voice by expert/trained
listener.
GRAS Scale
G- Grade of hoarseness
R-Rough
B-Breathy
A-Aesthenic
S-Strained

ACOUSTIC MEASURES

Acoustic measures quantify the sound pressure

waveform radiating from the mouth.
Acoustic spectrum-Series of sine waves (Fouriers
Analysis)
Fundamental Frequency =
1/ Time to complete one vibratory cycle.

ELECTROLARYNGORAPH

SPEECH & ELECTROLARYNGOGRAPH

PHONETOGRAM
Visual display of the dynamic range of the voice in
terms of frequency and vocal intensity
SPECTROGRAM
Three dimensional display of time, frequency,
amplitude of a recoded sound signal.
HARMONICS TO NOISE RATIO
Measured in dB
Mean intensity of average waveform/ Mean
intensity of the isolated noise component.

Aerodynamic measures
Air Flow
Air Volume
Air Pressure

DYSPHONIA SYMPTOM INDEX

+Maximum phonation time (s) x 0.13
+ Highest frequency (Fo) achievable x 0.0053
-Lowest Intensity (db) x 0.26
-Jitter (%) x 1.18
+12.6 (correctional factor)
= DSI score
+5 to -5

THANK
YOU