Anatomic Aspects Larynx: Sytem of muscles, cartileges and ligaments.
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1 Anatomic Aspects Larynx: Sytem of muscles, cartileges and ligaments. Primarly for controlling vocal foldsFolds 13-15mmGlottis: Slit like opening between foldsFolds move and change tensionVocal folds and epiglottis close during eating (also false vocal folds)False vocal folds are likely open during speech prouction
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
7 Mathematical Model of Glottal Flow Impulse trainGlottal flow over a single cycle (imp. Resp.)Glottal flow waveformP : pitch periodLooking through a small windowAbsence of window would yield impulses
8 Practical PhenomenaFixed 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/ whisperAspiration 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 phaseFolds 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
12 Vocal Tract ~17 cm and up to ~20 cm2 Vocal tract colors the source It also generates new sources for sound productionIt 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.formantRelated to bandwidth
13 All-pole model ck : pole, resonance freq., formant Formants: F1, F2, From low-to-highIn 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:TransitionalAffricateschewjustDiphtongshideboyoutnewSemi-VowelsLiquidsreadletGlidesweyouVowelsFrontCenterBackConsonantsNasalsPlosivesWhispersFricativesVoicedUnvoiced
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.