speech production1 anatomy of the vocal mechanism
TRANSCRIPT
Speech Production 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)1. Gender and age
• Males 120 Hz• Females 220 Hz• Children 270-300 Hz
2. Mass (relaxing and tensing of vocal folds)
3. 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