Dr Supreet Singh Nayyar AFMC For more presentations visit wwwnayyarENTcom 71512 wwwnayyarENTcom7152012 1 Physiology Of Phonation 71512 wwwnayyarENTcom 2 Introduction Relevant anatomy ID: 279426
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By Dr. Supreet Singh Nayyar, AFMCFor more presentations, visitwww.nayyarENT.com
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www.nayyarENT.com7/15/2012
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Physiology Of PhonationSlide2
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2IntroductionRelevant anatomyMechanism of voice productionProperties of phonationChanges in voiceSummaryReferences
OverviewSlide3
Human Voice
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www.nayyarENT.com3Human voice is uniquePortray our thoughts, emotions , joys and fearsSignatures of the individualsAncient Greeks thought that the voice actually originated in the heartSlide4
VOICE PRODUCTION
GENERATORPHONATORRESONATORARTICULATOR
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Framework
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www.nayyarENT.com5CartilagesMuscleIntrinsicExtrinsicNerves
Vocal foldsSlide6
Cartilages
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www.nayyarENT.com63 cartilages:Thyroid cartilageCricoid cartilage
ArytenoidsSlide7
Intrinsic Muscles
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www.nayyarENT.com7AbductorsPosterior cricoarytenoidAdductorsLateral cricoarytenoidInterarytenoidThyroarytenoidSlide8
Intrinsic Muscles (Contd)
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www.nayyarENT.com8TensorsCricothyroid VocalisSlide9
Extrinsic Muscles
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www.nayyarENT.com9ElevatorsPrimaryStylopharyngeusSalpingopharyngeusPalatopharyngeusThyrohyoidSlide10
Extrinsic Muscles (Contd)
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www.nayyarENT.com10Elevators (Contd.)SecondaryMylohyoidDigastricStylohyoidGeniohyoidSlide11
Extrinsic Muscles (Contd)
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www.nayyarENT.com11DepressorsSternohyoidSternothyroidOmohyoidSlide12
Nerve Supply
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www.nayyarENT.com12MotorAs discussed with musclesSensoryInternal laryngeal nerveRecurrent laryngeal nerveSlide13
Vocal Folds
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www.nayyarENT.com13Extend from the middle of the angle of the thyroid cartilage to the vocal process of the arytenoids cartilages.Parts Mucosa
Vocal ligament
BodySlide14
Vocal Fold Mucosa
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www.nayyarENT.com14Loose structure that is key to vocal fold vibration during sound production.EpitheliumBasement membraneSuperficial lamina propria.
Mucosal wave pattern
Reinke’s SpaceSlide15
Mucosal Wave Pattern
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The pattern of vibration is like a ‘wave’ travelling up them
The lower sections part first, and come together first
‘Cover’ (outer layer) and ‘body’ (inner layers) of folds are often distinguished, because they vibrate fairly independently
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Two-mass model
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The pattern of vibration can be quite well modelled using 2 quasi-independent masses for each vocal fold
One large, one small
The two connected by a spring
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What moves vibrators
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www.nayyarENT.com17TensorsAdductorsAbductorsBernoulli effectSlide18
Bernoulli Effect
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www.nayyarENT.com18Inverse relationshipIncrease in air flow results in air pressure decreaseSlide19
Myoelastic Aerodynamic Theory Of Vocal Fold Vibration (Van den Berg, 1950s)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 apartAir 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
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www.nayyarENT.com20Sound 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 SignalSlide21
Amplitude
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www.nayyarENT.com21Amplitude of the pressure wave is perceived as loudness or sound intensityThe amplitude is largely determined by the force of the transglottal airflow. “Shimmer” or amplitude perturbationSlide22
Frequency
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www.nayyarENT.com22The frequency of the glottal signal is a result of the number of vibratory cycles / sec ( measured in Hz)Function of Vocal fold lengthElasticityTension MassSlide23
Pitch
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www.nayyarENT.com23Frequency, intensity and spectral properties of sound interact in very complex ways to lead to a given pitch perception. “Jitter” or pitch perturbationIt is generally accepted that there are three pitch registers Loft (or falsetto) registerModal (or middle) register Pulse (or chest) registerSlide24
Loft or Falsetto Register
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www.nayyarENT.com24A singing technique that produces sounds that are pitched higher than the singer's normal range Vocal folds are lengthened and become extremely thinOnly 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 metalVoice of mickey mouse is another example of falsettoSlide25
Modal or Middle Register
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www.nayyarENT.com25 Complete glottal closure occurs Results in the majority of the mid frequency range voice
Vocal fold mucosa vibrates independently of the vocalisSlide26
Pulse or Chest register
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www.nayyarENT.com26Also 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 foldsSlide27
AttacksThere are three kinds of attacks (or beginning of the each voiced sound)SimultaneousGlottalBreathy
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Changes in voice
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www.nayyarENT.com28PhysiologicalAgeGenderPuberphoniaSlide29
Changes in voice (Contd.)
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www.nayyarENT.com29PathologicalProcesses involved in voice disordersGeneration of air pressure Glottic closureVocal fold vibrationVoice loudnessVoice pitch Slide30
Generating Air Pressure
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www.nayyarENT.com30Pulmonary diseaseAsthmaSubglottic stenosisParesis of muscles
SymptomsShortness of breath
Weak voice Slide31
Glottic Closure
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www.nayyarENT.com31Nerve ParesisUnilateral Recurrent Laryngeal NerveBilateral Recurrent Laryngeal NerveUnilateral Superior Laryngeal NerveBilateral Superior Laryngeal NerveCombined Recurrent & Superior laryngeal Nerve
Symptoms
HoarsenessEffortful phonation
Vocal fatigue Slide32
Vocal Fold Vibration
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www.nayyarENT.com32Vocal fold scar or vocal fold lesions Cysts, nodules, polyps ,papilloma ,vocal fold granulomaSwelling and inflammation (reflux laryngitis, viral laryngitis) Reinke’s edema Paresis, haemorrhage, vascular ectasis
Symptoms
HoarsenessEffortful phonation
Weak voice
Speaking voice lower than usual “glottal fry”Slide33
Voice Loudness
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www.nayyarENT.com33Vocal fold scarParesis
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 breaksSlide34
Voice Pitch
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www.nayyarENT.com34SLN paresisVocal fold scarReinke’s edemaVocal fold lesionsSymptoms
Unable to hit high notes
Voice breaksSlide35
Dysphonia Plica Ventricularis
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www.nayyarENT.com35Voice is produced by ventricular folds (false cords) Voice is rough, low pitch and unpleasantMay 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 cordsSlide36
Non Vocalized SoundsWhisperWhistle
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Summary
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www.nayyarENT.com37Production of voice consists of 4 partsPhonation involves vibration of vocal cords leading to production of soundWave like motion of mucosal folds Myoelastic aerodynamic theoryAny changes in vocal cord or vibratory framework will lead to changes in voiceSlide38
References
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www.nayyarENT.com38Scott Brown ORL HNS,7th EditionCummings ORL HNS, 4th EditionOCNA 2006, Vol. 39, Issue 1, PhonosurgeryOCNA 2007, Vol. 40, Issue 5, The Professional VoiceGray’s Anatomy, 38th Edition Various sources from internetSlide39
Thank You
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