06. Physio of Phonation
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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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