06. Physio of Phonation

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PHYSIOLOGY OF PHONATION AND INV OF HOARSENESS OF VOICE Dr R Anbuchezhian

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PHYSIOLOGY OF PHONATION AND INV OF HOARSENESS OF VOICEDr R Anbuchezhian Physical act of sound production in larynx by vocal cords vibrating in an expiratory blast of air.PHONATIONPROPERTIES OF SOUNDSOUND

INTENSITY

FREQUENCY

TIMBRE

RESONANCEVOICE PRODUCTION BY LARYNXRespiratory bellows

Vibratory mechanism

Resonating chambersTHEORIES OF PHONATIONI. NEUROMUSCULAR THEORYIII. COVER/BODY THEORYII. AERODYNAMIC THEORYNEUROCHRONAXIC THEORY OF HUSSON, 1953Neuromuscular theory, Clonic theoryBy 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 should contract in the same frequency

Evidence refuting neuromuscular theoryFailure 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 theoryModels, 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 THEORYINITIATION OF VOICE & PHONATIONPrephonatory inspiratory phase

PhonationVC AdductionPulmonic 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 CYCLEAERODYNAMIC SEPARATIONRECOILADDUCTIONFACTORS CAUSING VF TO RETURN TO MIDLINEBERNOULLIS EFFECT.

ELASTIC FORCES IN VOCAL FOLDS

DECREASED PRESSURESTAGES OF V C VIBRATION

Periods of V C Contact / lack1.Closing2. Closed3. Opening 4. Open Cover /Body Theory

Body VocalisCover Mucous membrane

Undulating wave of movement of mucous membrane over the firm vocalis muscle producing the sound wave. REGISTERSPerceptually distinct regions of vocal quality over certain ranges of pitch and loudness.Loft Register/Falsetto registerModalPulse 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 productionVOICE SPEECH PRODUCTIONVibration 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

QualityFrequencyAmplitudeCHARACTERISTICS OF GLOTTIC SOUND QUALITY FREQUENCY AMPLITUDEQUALITYQuality depends on vibratory characteristics of the laryngeal structures. Regularity of wavesBreathy 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 soundCHARACTERISTICS OF GLOTTIC SOUND QUALITY FREQUENCY AMPLITUDEFREQUENCYDef : 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 cordCHARACTERISTICS OF GLOTTIC SOUND QUALITY FREQUENCY AMPLITUDEAMPLITUDEDef : Size of the oscillation of the vocal fold.

Shimmers/amplitude perturbation - short term variance in the intensity of the vocal signalPITCH CONTROL CHANGES IN VOCAL FOLD LENGTH & TENSION

CONTRACTION OF THRYOARYTENOID DECREASES PITCH

CONTRACTION OF CRICOTHYROID INCREASES PITCH

TENSIONSIZE & PHYSICAL PROPERTIES OF LARYNX

CHILDREN HAVE SMALLER LARYNX HIGHER PITCHPUBERTY RAPID INCREASE IN LARYNX SIZE - UNSTABLE PITCH CONTROLOLD AGE LOSS OF ELASTICITY - INCREASED PITCHMODIFYING THE GLOTTIC SIGNALRaw glottic signal is modified into speech by Resonance Articulation

VOCAL RESONANCESUPRALARYNGEAL TRACT ACTS AS THE RESONATING CHAMBER.

LEADS TO PROLONGATION - AMPLIFICATION - FILTERING OF SOUND

VOCAL RESONANCEOral resonanceDegree of jaw mvmt, mouth opening, tongue raising, Pharyngeal constriction

Nasal resonanceVelopharyngeal spincter

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

Source - larynx

Filters - lips , tongue , palate , pharynx ( Form consonants and vowels)

VOWELSThese are sounds where there is no Obsrtuction to flow of air as it passes from larynx to lipsEg : A, E, I, O, U

CONSONANTSThese are sounds where there is more definitive obstruction to airEg : P, B, M, W, F, T, S, Z, R,

Different consonants are produced by : - place of articulation - Manner of articulation - State of larynx CONSONANTSBILABIALDENTALLABIODENTALALVEOLARPALATALVELARGLOTTALBASED ON PLACE OF ARTICULATIONCONSONANTS BASED ON PLACE OF ARTICULATIONBILABIAL -

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

CONSONANTS BASED ON PLACE OF ARTICULATIONLABIODENTAL TOP TEETH ANDLOWER LIP - F, V

CONSONANTS BASED ON PLACE OF ARTICULATIONDENTAL

- TONGUE TIP WITH TOP TEETH OCCLUSION

- th

CONSONANTS BASED ON PLACE OF ARTICULATIONALVEOLAR

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

CONSONANTS BASED ON PLACE OF ARTICULATIONPALATAL

MIDDLE TONGUEWITHHARD PALATE

- Y

CONSONANTS BASED ON PLACE OF ARTICULATIONVELAR POSTR TONGUEANDSOFT PALATE

- K, G, ng

CONSONANTS BASED ON MANNER OF ARTICULATIONPlosives : p, b, t, d, k, gFricatives : F, V, S, Z, thAffricatives : ch, djNASAL : M, N, ng Approximant : w, y, l, r, h VoiceAcoustic output from the vocal tract that are characterised by their dependence on the vocal fold vibratory inputs

Pathological phonationImbalance in normal ratio of periodic sound and noice components of acoustic signal resulting in poor voice quality

HOARSENESSHoarseness 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.V247WorkupEVALUATION OF A PATIENT WITH HOARSENESS INCLUDES THE FOLLOWING: -

- HISTORY

- PHYSICAL EXAMINATION

- ANCILLARY TESTS

HOARSENESSInfection - laryngitisTrauma - Nerve paralysis - Laryngeal fractures - During Intubation Arytenoids dislocation Mucosal lacerations- Granuloma HistoryHISTORYHistory Pulmonary conditions - COPD - Asthma Gastrointestinal LPRAutoimmune - RA Endocrine - hypothyroidism (Edematous) -Danazol in female (Irreversible enlargement of larynx)HISTORYSurgical history - Skull base procedures - Thyroidectomies - Aortic aneurysm repairsSocial history - Tobacco - Alcohol - TalkativenessOccupational history - Voice abuseToxic exposures - Pollutants, pollen grains, ethyl alcohol, tobacco, allergiesHistoryHISTORYHISTORYMuscle Tension dysphoniaStress, anxiety, depression, conversion disorderPostural and breathing problems, poor vocal hygieneExposure to excessive environmental dust, smoke, fumes

Puberphonia / Mutational falsetto/ Adolescent transitional voice disorder Fundamental within female speaking range. (Never broken)

PresbylaryngisAge induced chages after 50 yrs

COMMON SYMPTOM SUGGESTIVE OF SPECIFIC DIAGNOSIS

LARYNGEAL EXAMINATION

- INDIRECT LARYNGOSCOPY

- FLEXIBLE LARYNGOSCOPY

- RIGID LARYNGOSCOPY

INDIRECT LARYNGOSCOPYADVANTAGESQUICKINEXPENSIVELITTLE EQUIPMENT

DISADVANTAGESGAGANATOMIC FEATURESNONPHYSIOLOGIC

FLEXIBLE LARYNGOSCOPYADVANTAGESWELL TOLERATEDCOMPLETE EXAMINATIONVIDEO DOCUMENTATION

DISADVANTAGESMORE TIMEEXPENSIVE

RIGID LARYNGOSCOPYADVANTAGESBEST IMAGESVIDEO DOCUMENTATION

DISADVANTAGESEXPENSIVENONPHYSIOLOGICGAGREQ OF GA

VIDEOSTROBOSCOPYTwo 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 FibrescopePermits accurate visualization of epithelial abnormalities which are missed out on IDL due to fast vibrationsVideo recordingDetailed reviewComparison after treatmentVIDEOSTROBOSCOPYVOCAL FOLD CLOSURE PATTERN

VOCAL FOLD VIBRATORY PATTERN

MUCOSAL WAVE OF EACH VOCAL FOLD

SYMMETRYVIDEOSTROBOSCOPY

ADVANTAGES: ALLOWS APPARENT SLOW MOTION ASSESSMENT OF MUCOSAL VIBRATORY DYNAMICS, VIDEO DOCUMENTATION

DISADVANTAGES: TIME CONSUMING, EXPENSIVE

V3PANENDOSCOPYINDICATIONS

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 CANCERS WITH NEW ONSET HOARSENESS

OTHER TESTSLABS: TSH, LFT

PLAIN FILMS: CXR, LAT NECK

CT SCAN :

MRI -

BA SWALLOW LARYNGEAL EMGMYOPATHY 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 evaluationPerceptual evaluation of voiceProcess of assessing and grading the severity of voice disorder in a speakers voice by expert/trained listener.

GRAS Scale G- Grade of hoarsenessR-RoughB-BreathyA-AesthenicS-StrainedAcoustic measuresAcoustic 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

PHONETOGRAMVisual display of the dynamic range of the voice in terms of frequency and vocal intensitySPECTROGRAMThree dimensional display of time, frequency, amplitude of a recoded sound signal.HARMONICS TO NOISE RATIOMeasured in dBMean intensity of average waveform/ Mean intensity of the isolated noise component.

Aerodynamic measuresAir FlowAir VolumeAir PressureDysphonia 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

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