Transcript Physiology Of Phonation

Physiology Of Phonation
By
Dr. Supreet Singh Nayyar, AFMC
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Overview
 Introduction
 Relevant anatomy
 Mechanism of voice production
 Properties of phonation
 Changes in voice
 Summary
 References
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Human Voice
 Human voice is unique
 Portray our thoughts, emotions , joys
and fears
 Signatures of the individuals
 Ancient Greeks thought that the voice
actually originated in the heart
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VOICE
PRODUCTION
•GENERATOR
•PHONATOR
•RESONATOR
•ARTICULATOR
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Framework
 Cartilages
 Muscle
 Intrinsic
 Extrinsic
 Nerves
 Vocal folds
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Cartilages
 3 cartilages:
• Thyroid cartilage
• Cricoid cartilage
• Arytenoids
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Intrinsic Muscles
 Abductors
 Posterior cricoarytenoid
 Adductors
 Lateral cricoarytenoid
 Interarytenoid
 Thyroarytenoid
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Intrinsic Muscles (Contd)
 Tensors
 Cricothyroid
 Vocalis
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Extrinsic Muscles
 Elevators
 Primary
 Stylopharyngeus
 Salpingopharyngeus
 Palatopharyngeus
 Thyrohyoid
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Extrinsic Muscles (Contd)
 Elevators (Contd.)
 Secondary
 Mylohyoid
 Digastric
 Stylohyoid
 Geniohyoid
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Extrinsic Muscles (Contd)
 Depressors
 Sternohyoid
 Sternothyroid
 Omohyoid
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Nerve Supply
 Motor
 As discussed with muscles
 Sensory
 Internal laryngeal nerve
 Recurrent laryngeal nerve
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Vocal Folds
• Extend from the middle of the angle of the thyroid
cartilage to the vocal process of the arytenoids
cartilages.
• Parts
1. Mucosa
2. Vocal ligament
3. Body
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Mucosal Wave Pattern
1
4
•The pattern of vibration is
like a ‘wave’ travelling up
them
•The lower sections part first,
and come together first
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2
5
3
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•‘Cover’ (outer layer) and
‘body’ (inner layers) of folds
are often distinguished,
because they vibrate fairly
independently
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Two-mass model
1
4
•The pattern of vibration can
be quite well modelled using
2 quasi-independent masses
for each vocal fold
•One large, one small
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2
5
3
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•The two connected by a
spring
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What moves vibrators
 Tensors
 Adductors
 Abductors
 Bernoulli effect
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Bernoulli Effect
 Inverse relationship
 Increase in air flow results
in air pressure decrease
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Myoelastic Aerodynamic Theory Of Vocal
Fold Vibration (Van den Berg, 1950s)
1.
2.
3.
4.
5.
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Muscular activity rotates and rocks the
arytenoid cartilages so that their vocal
processes come together in the midline, thus
positioning the vocal folds close together or in
actual contact.
Air pressure increases below the glottis until
folds forced apart
Air travels faster through the glottis when it is
narrow. This causes a local drop in air pressure
(Bernoulli effect) which causes the folds to be
sucked towards each other.
The Bernoulli effect, together with the elastic
recoil force exerted by the displaced vocal
folds, causes complete glottal closure again.
The process begins again at step 2.
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Properties of Phonation
Sound can be described in terms of the physical properties of its pressure
waveform
• Amplitude
• Frequency
• Pitch
Spectogram of Human Voice
with Rich Harmonic Content
Spectogram of FM Signal
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Amplitude
 Amplitude of the pressure wave is perceived as
loudness or sound intensity
 The amplitude is largely determined by the force of the
transglottal airflow.
 “Shimmer” or amplitude perturbation
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Frequency
 The frequency of the glottal signal is a result of the number
of vibratory cycles / sec ( measured in Hz)
 Function of
 Vocal fold length
 Elasticity
 Tension
 Mass
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Pitch
 Frequency, intensity and spectral properties of sound
interact in very complex ways to lead to a given pitch
perception.
 “Jitter” or pitch perturbation
 It is generally accepted that there are three pitch registers
– Loft (or falsetto) register
– Modal (or middle) register
– Pulse (or chest) register
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Loft or Falsetto Register
 A singing technique that produces sounds that are pitched higher than




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the singer's normal range
Vocal folds are lengthened and become extremely thin
Only the edges of the vocal cord vibrate, not the entire vocal cord
It is a very common technique in soul music, and has also been made
popular in heavy metal
Voice of mickey mouse is another example of falsetto
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Modal or Middle Register
• Complete glottal closure occurs
• Results in the majority of the mid frequency range voice
• Vocal fold mucosa vibrates independently of the vocalis
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Pulse or Chest register
• Also known as strohbass (straw bass)
• Vocal folds vibrate between 30 and 90 hz
• Frying pan sound of eggs frying
(also called glottal fry)
• Low subglottal pressure
• Tension of the vocalis is significantly reduced
relative to modal vibration, so that the vibrating
margin is flaccid and thick
• The lateral portion of folds is tensed creating thick
folds
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Attacks
 There are three kinds of attacks (or beginning of the each
voiced sound)
 Simultaneous
 Glottal
 Breathy
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Changes in voice
 Physiological
• Age
• Gender
• Puberphonia
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Changes in voice (Contd.)
 Pathological
 Processes involved in voice disorders
 Generation of air pressure
 Glottic closure
 Vocal fold vibration
 Voice loudness
 Voice pitch
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Generating Air Pressure
 Pulmonary disease
 Asthma
 Subglottic stenosis
 Paresis of muscles
 Symptoms
 Shortness of breath
 Weak voice
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Glottic Closure
 Nerve Paresis
 Unilateral Recurrent Laryngeal Nerve
 Bilateral Recurrent Laryngeal Nerve
 Unilateral Superior Laryngeal Nerve
 Bilateral Superior Laryngeal Nerve
 Combined Recurrent & Superior laryngeal Nerve
 Symptoms
 Hoarseness
 Effortful phonation
 Vocal fatigue
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Vocal Fold Vibration
 Vocal fold scar or vocal fold lesions
 Cysts, nodules, polyps ,papilloma ,vocal fold granuloma
 Swelling and inflammation (reflux laryngitis, viral laryngitis)
 Reinke’s edema
 Paresis, haemorrhage, vascular ectasis
 Symptoms
 Hoarseness
 Effortful phonation
 Weak voice
 Speaking voice lower than usual “glottal fry”
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Voice Loudness
• Vocal fold scar
• Paresis
• Vocal fold lesions: cysts, nodules, polyps, papilloma
• Vocal fold granuloma
• Swelling and inflammation (reflux laryngitis, viral
laryngitis)
• Symptoms
 Unable to project voice
 Weak voice
 Voice breaks
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Voice Pitch
 SLN paresis
 Vocal fold scar
 Reinke’s edema
 Vocal fold lesions
 Symptoms
 Unable to hit high notes
 Voice breaks
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Dysphonia Plica Ventricularis
 Voice is produced by ventricular folds (false cords)
 Voice is rough, low pitch and unpleasant
 May be secondary to impaired function of the true vocal
cord such as paralysis, fixation, surgical excision or
tumors
 Ventricular bands in these situations try to compensate
or assume phonatory function of true vocal cords
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Non Vocalized Sounds
 Whisper
 Whistle
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Summary
 Production of voice consists of 4 parts
 Phonation involves vibration of vocal cords leading to
production of sound
 Wave like motion of mucosal folds
 Myoelastic aerodynamic theory
 Any changes in vocal cord or vibratory framework will lead
to changes in voice
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References
 Scott Brown ORL HNS,7th Edition
 Cummings ORL HNS, 4th Edition
 OCNA 2006, Vol. 39, Issue 1, Phonosurgery
 OCNA 2007, Vol. 40, Issue 5, The Professional Voice
 Gray’s Anatomy, 38th Edition
 Various sources from internet
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Thank You
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