Physiology Of Phonation By Dr Supreet Singh Nayyar

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

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

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 3 www. nayyar. ENT. com 7/15/12

VOICE PRODUCTION • GENERATOR • PHONATOR • RESONATOR • ARTICULATOR 7/15/12 www. nayyar. ENT. com 4

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

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

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

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

Extrinsic Muscles Elevators 9 Primary Stylopharyngeu s Salpingopharyn geus Palatopharynge us www. nayyar. ENT. com Thyrohyoid 7/15/12

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

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

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

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 13 www. nayyar. ENT. com 7/15/12

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 15 2 5 3 6 www. nayyar. ENT. com • ‘Cover’ (outer layer) and ‘body’ (inner layers) of folds are often distinguished, because they vibrate fairly independently 7/15/12

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 16 2 5 3 6 www. nayyar. ENT. com • The two connected by a spring 7/15/12

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

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

Myoelastic Aerodynamic Theory Of Vocal Fold Vibration (Van den Berg, 1950 s) 1. 2. 3. 4. 5. 19 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. www. nayyar. ENT. com 7/15/12

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 20 www. nayyar. ENT. com 7/15/12

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 21 www. nayyar. ENT. com 7/15/12

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 22 www. nayyar. ENT. com 7/15/12

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 23 www. nayyar. ENT. com 7/15/12

Loft or Falsetto Register 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 24 www. nayyar. ENT. com 7/15/12

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 25 www. nayyar. ENT. com 7/15/12

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 26 www. nayyar. ENT. com 7/15/12

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

Changes in voice Physiological • Age • Gender • Puberphonia 28 www. nayyar. ENT. com 7/15/12

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

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

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 31 www. nayyar. ENT. com 7/15/12

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” 32 www. nayyar. ENT. com 7/15/12

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 33 www. nayyar. ENT. com 7/15/12

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

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 35 www. nayyar. ENT. com 7/15/12

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

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 37 www. nayyar. ENT. com 7/15/12

References 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 38 www. nayyar. ENT. com 7/15/12

Thank You 39 www. nayyar. ENT. com 7/15/12