1. By Dr. Supreet Singh Nayyar, AFMC For more presentations, visit www.nayyarENT.com 7/15/12 www.nayyarENT.com7/15/2012 1 Physiology Of Phonation

2. 7/15/12 www.nayyarENT.com 2 Introduction Relevant anatomy Mechanism of voice production Properties of phonation Changes in voice Summary References Overview

3. Human Voice 7/15/12 www.nayyarENT.com 3 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

4. VOICE PRODUCTION GENERATOR PHONATOR RESONATOR ARTICULATOR 7/15/12www.nayyarENT.com 4

5. Framework 7/15/12 www.nayyarENT.com 5 Cartilages Muscle Intrinsic Extrinsic Nerves Vocal folds

6. Cartilages 7/15/12 www.nayyarENT.com 6 3 cartilages: Thyroid cartilage Cricoid cartilage Arytenoids

7. Intrinsic Muscles 7/15/12 www.nayyarENT.com 7 Abductors Posterior cricoarytenoid Adductors Lateral cricoarytenoid Interarytenoid Thyroarytenoid

8. Intrinsic Muscles (Contd) 7/15/12 www.nayyarENT.com 8 Tensors Cricothyroid Vocalis

9. Extrinsic Muscles 7/15/12 www.nayyarENT.com 9 Elevators Primary Stylopharyngeus Salpingopharyngeus Palatopharyngeus Thyrohyoid

10. Extrinsic Muscles (Contd) 7/15/12 www.nayyarENT.com 10 Elevators (Contd.) Secondary Mylohyoid Digastric Stylohyoid Geniohyoid

11. Extrinsic Muscles (Contd) 7/15/12 www.nayyarENT.com 11 Depressors Sternohyoid Sternothyroid Omohyoid

12. Nerve Supply 7/15/12 www.nayyarENT.com 12 Motor As discussed with muscles Sensory Internal laryngeal nerve Recurrent laryngeal nerve

13. Vocal Folds 7/15/12 www.nayyarENT.com 13 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

14. Vocal Fold Mucosa 7/15/12 www.nayyarENT.com 14 Loose structure that is key to vocal fold vibration during sound production. Epithelium Basement membrane Superficial lamina propria. Mucosal wave pattern Reinke’s Space

15. Mucosal Wave Pattern 7/15/12 www.nayyarENT.com 15 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 1 2 3 4 5 6

16. Two-mass model 7/15/12 www.nayyarENT.com 16 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 1 2 3 4 5 6

17. What moves vibrators 7/15/12 www.nayyarENT.com 17 Tensors Adductors Abductors Bernoulli effect

18. Bernoulli Effect 7/15/12 www.nayyarENT.com 18 Inverse relationship Increase in air flow results in air pressure decrease

19. Myoelastic Aerodynamic Theory Of Vocal Fold Vibration (Van den Berg, 1950s) 1. 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. 2. Air pressure increases below the glottis until folds forced apart 3. 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. 4. The Bernoulli effect, together with the elastic recoil force exerted by the displaced vocal folds, causes complete glottal closure again. 5. The process begins again at step 2. 7/15/12 www.nayyarENT.com 19

20. Properties of Phonation 7/15/12 www.nayyarENT.com 20 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

21. Amplitude 7/15/12 www.nayyarENT.com 21 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

22. Frequency 7/15/12 www.nayyarENT.com 22 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

23. Pitch 7/15/12 www.nayyarENT.com 23 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

24. Loft or Falsetto Register 7/15/12 www.nayyarENT.com 24 A singing technique that produces sounds that are pitched higher than 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

25. Modal or Middle Register 7/15/12 www.nayyarENT.com 25 Complete glottal closure occurs Results in the majority of the mid frequency range voice Vocal fold mucosa vibrates independently of the vocalis

26. Pulse or Chest register 7/15/12 www.nayyarENT.com 26 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

27. Attacks There are three kinds of attacks (or beginning of the each voiced sound) Simultaneous Glottal Breathy 7/15/12 www.nayyarENT.com 27

28. Changes in voice 7/15/12 www.nayyarENT.com 28 Physiological Age Gender Puberphonia

29. Changes in voice (Contd.) 7/15/12 www.nayyarENT.com 29 Pathological Processes involved in voice disorders Generation of air pressure Glottic closure Vocal fold vibration Voice loudness Voice pitch

30. Generating Air Pressure 7/15/12 www.nayyarENT.com 30 Pulmonary disease Asthma Subglottic stenosis Paresis of muscles Symptoms Shortness of breath Weak voice

31. Glottic Closure 7/15/12 www.nayyarENT.com 31 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

32. Vocal Fold Vibration 7/15/12 www.nayyarENT.com 32 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”

33. Voice Loudness 7/15/12 www.nayyarENT.com 33 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

34. Voice Pitch 7/15/12 www.nayyarENT.com 34 SLN paresis Vocal fold scar Reinke’s edema Vocal fold lesions Symptoms Unable to hit high notes Voice breaks

35. Dysphonia Plica Ventricularis 7/15/12 www.nayyarENT.com 35 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

36. Non Vocalized Sounds Whisper Whistle 7/15/12 www.nayyarENT.com 36

37. Summary 7/15/12 www.nayyarENT.com 37 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

38. References 7/15/12 www.nayyarENT.com 38 Scott Brown ORL HNS,7 th Edition Cummings ORL HNS, 4 th Edition OCNA 2006, Vol. 39, Issue 1, Phonosurgery OCNA 2007, Vol. 40, Issue 5, The Professional Voice Gray’s Anatomy, 38 th Edition Various sources from internet

39. Thank You 7/15/12 www.nayyarENT.com 39