Anatomy of the vocal mechanism

1. Anatomy of the vocal mechanism Speech Production

2. Speech Production

3. Speech Production

4. Phonation • Myoelastic aerodynamic theory of phonation. • Fundamental frequency • Harmonics Speech Production

5. Phonation • Production of sound in larynx. • Anytime you use voicing to produce a sound (e.g., vowels and voiced consonants) phonation will take place. • Myoelastic aerodynamic theory of phonation (see next slide) Speech Production

6. Myoelastic Aerodynamic Theory of Phonation • Two stage process • Stage one: Myoelastic phase. Elasticity of vocal folds helps them close. • Stage two: Aerodynamic phase • Sub-glottal pressure forces vocal folds apart • Bernoulli Effect helps vocal folds close Speech Production

7. Bernoulli Effect • As air velocity increases, air pressure decreases. Speech Production

8. Myoelastic Aerodynamic Theory of Phonation (continued) • Another way of stating the MA theory is to see how vocal folds open and close. • Opened due to… • Increase in subglottal pressure • Closed due to… • Vocal fold elasticity • Bernoulli effect Speech Production

9. Fundamental Frequency • Refers to the fundamental frequency to which the vocal folds vibrate at. • Variables that affect fundamental frequency (fo) • Gender and age • Males 120 Hz • Females 220 Hz • Children 270-300 Hz • Mass (relaxing and tensing of vocal folds) • Intensity (Bernoulli effect) Speech Production

10. Harmonics • Discussed during acoustics section. • Remember… • During phonation you will fo along with a series of harmonics • Spacing between harmonics will equal the fo. Speech Production

11. Harmonics Speech Production

12. Jitter and Shimmer • Jitter • Variations in the Fo, aka frequency perturbation • Periods between individual cycles vary slightly (e.g., 200, 201, 199 Hz, etc.) • Shimmer • Variations in Intensity, aka amplitude perturbation Speech Production

13. Jitter and Shimmer continued • Causes of jitter and shimmer • Neurological • Biomechanical • Aerodynamic • Acoustic (hearing loss) • Normal values • Jitter (0.2 to 1%) of frequency • Shimmer (< 0.5 dB) Speech Production

14. Jitter and Shimmer continued • Clinical Applications • Vocal aging • Increased for children and elderly • Neurological pathology • Parkinson’s Disease • Amyotrophic Lateral Sclerosis • Laryngeal Cancer • Increased vocal fold mass (e.g., nodule, polyp, etc.) • Stuttering in young children (shimmer) Speech Production

15. Vocal Registers • Pulse • Modal • Midvoice • Falsetto Speech Production

16. Pulse • Vocal frequency is 30 to 80 Hz in males and 90 to 165 Hz in females. • VFs are closed about 90% or time and open 10%. • Perceived as burst of acoustic energy but with silence gaps. • Normal at end of phrases and sentences. • Clinical problem if used habitually. Speech Production

17. Modal and Midvoice • Modal • About 100 to 150 Hz in males • About 175 to 300 Hz in females • Perceived as normal speech • Midvoice • About 200 to 300 Hz in males • About 350 to 600 Hz in females • Often used in singing situation Speech Production

18. Falsetto • Vocal frequency of about 350 to 500 Hz in males. • About 650 to 1000 Hz in females. • Vocal folds may not meet in middle because of abnormal tension and may be breathy • “Reedy sound” due to widely spaced harmonics. • Falsetto’s are not a part of normal speech. Speech Production

19. Summary Speech Production