1. Anatomic Aspects Larynx: Sytem of muscles, cartileges and ligaments.
Primarly for controlling vocal folds
Folds 13-15mm
Glottis: Slit like opening between folds
Folds move and change tension
Vocal folds and epiglottis close during eating (also false vocal folds)
False vocal folds are likely open during speech prouction

3. Larynx Top View
Voicing
Breathing

4. Three Primary States of Vocal Folds: Breathing, Voiced and Unvoiced
BREATHING: Arytenoid cartileges move outward, fold muscles are relaxed.
VOICING:The size/mass and tension of folds determines pitch ( Hz)
MOTION OF FOLDS DURING VOICING

5. Mechanical Model of Folds

6. Periodic Glottal Flow Velocity

7. Mathematical Model of Glottal Flow
Impulse train
Glottal flow over a single cycle (imp. Resp.)
Glottal flow waveform
P : pitch period
Looking through a small window
Absence of window would yield impulses

8. Practical Phenomena
Fixed pitch is not possible even in sustained cases  “pitch jitter”
Airflow velocity within a glottal cycle may differ across consecutive periods  “shimmer”
Jitter and shimmer yield “naturalness” and contributes to the “voice character”.

9. UNVOICING  no vibration of vocal folds
Folds are close to each other but open and tense
 Turbulance / aspiration
/h/ whisper
Aspiration normally occurs during voicing also.
If strong  breathy voice.

10. Other Forms of Vocal Fold Movement
Creaky Voice: Folds are very tense and vibrating part is small.
It is a harsh sounding voice.
High and irregular pitch is observed.
Vocal Fry: When folds are massy and relaxed.
Abnormally low and irregular pitch.
Secondary glottal pulses arise within the open phase
Folds may couple with false vocal folds.
Vocal fry may ocur in normal speech at the edn of a phrase when folds relax and lung pressure decreases.
Diplophonic: Secondary pulses in the closed phase.
Generally in low pitch speakers.
It may arise in normal voices at the end of a phrase or word.
Vocal fry and diplophonic can be modelled as

11. Vocal Fry
Diplophonic

12. Vocal Tract ~17 cm and up to ~20 cm2 Vocal tract colors the source
It also generates new sources for sound production
It can be approximated by a linear filter.
Resonance frequencies are called “formants”
Formant bandwidth and formant amplitude.
The peaks of the spectrum of vocal tract response are approximately formants.
formant
Related to bandwidth

13. All-pole model ck : pole, resonance freq., formant
Formants: F1, F2, From low-to-high
In general, formant frequencies decreaseas vocal tract length increases. (male, female, child)

14. Vocal Tract Output Vocal tract impulse response
In a small window (to pick a stationary portion)

16. Speech Sounds - Phonemes
Broad classification is “vowels” and “consonants”.
Finer classification:
Transitional
Affricates
chew
just
Diphtongs
hide
boy
out
new
Semi-Vowels
Liquids
read
let
Glides we
you
Vowels
Front
Center
Back
Consonants
Nasals
Plosives
Whispers
Fricatives
Voiced
Unvoiced

17. Vowels: No constriction along the vocal tract.
Voiced. Vocal folds vibrate.
Front, center or back; according to the tongue position.
Rounded, unrounded according to the position of lips.
Also, high-low according to tongue height.
Normal breathing yields low sound. The high intensity of vowels is because of vocal fold vibration.

18. Vowels

19. Fricatives

20. Plosives

21. Nasals

22. Spectrogram of the diphtong /O/ in “boy”.
Transitional Sounds
Spectrogram of the diphtong /O/ in “boy”.