SOMAYEH SHAHSAVARANI

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Speech Production

Language

Language

Speech

SigningWriting

Painting

Studying Methods

Classical Methods (Invasive) Surgery Operation

Modern Methods (Non-invasive) MRI FMRI PET-Scan (Positron Emission Tomography)

Speech

Speech Speech Production Speech Perception Speech Signal Processing

Model Typescontroller

Old models The Traditional Locationist Model

Speech Production, Grammar: Broca’s Area Speech perception, Dictionary: Wernicke’s Area

New Models Circuit Models

Speech Production: Broca’s Area, Basal Ganglia, Internal Capsule (the nerve fibers that connect the neocortex to subcortical structures)

Speech ProductionPlant

Articulation

Phonation

Respiration

Speech ProductionPlant

Plant

Speech Sounds

The speech phonemes are generally divided into two groups: Vowels

The vowels are produced by open mouth The sound which is produced by vocal cords (vocal folds)

vibration is the source of vowels. The vocal tract that is located over the vocal cords filters the sound. Different configurations of vocal tract lead to different vowels.

Consonants consonants are produced by nearly closed mouth Consonants are produced by the air passing through the

oral cavity and oral nasal. Different configurations of tongue, teeth and gum lead to different consonants.

Fundamental Frequency and Formant Frequencies

Fundamental Frequency: Vowel sounds are produced by vocal cords vibrations. The

vibrations produce an alternating wave. Any alternating wave has a fundamental frequency and a number of harmonics. These harmonics are the integer multiples of the fundamental frequency. The fundamental frequency of the alternating wave produced by vocal cords vibration is related to vocal cords vibration speed. For example, for a fundamental frequency, 100 Hz, vocal cords open and close 100 turns per a second. It is important to be mentioned that the vowels are not distinguished by fundamental frequency. A vowel may be produced with different fundamental frequency. On the other hand, at a specific frequency, some different vowels may be produced.

Fundamental Frequency and Formant Frequencies

Formant Frequencies :

Different vowels are distinguishable by their formant frequencies. The vocal tract which is located over the larynx acts as a filter. It strengthens some harmonic frequencies and attenuates some others. The harmonics which are strengthened are called formant frequencies. Different vowels have different formant frequencies.

Face Muscles

The Muscle of Expression The Muscles of the Mouth

Orbicular Oris Levator Labii Superior and Alaeque Nasi Levator Labii Superior Depressor Labii Inferioris

The Muscle of Mastication Temporal Muscle Masseter Medial Pterygoid Lateral Pterygoid

Speech Production Learning

Speech production is a developmental process.

Speech Motor Development

Speech Production Modeling

Vocal Tract and Articulators Modeling Mass-Spring-Damper

The Underlying Neural Basis of Speech Production and Learning Modeling Artificial Neural Networks Model-Predictive Control

DIVA Model (2005)

Directions In to Velocities of Articulators

Daliri Model (2007)

Kröger Model (2008)

Speech Production Learning

Speech Acquisition Auditory Feedback Babbling phase

Speech Motor Development Somatosensory Feedback (Proprioceptive(Muscle Spindle) +

Tactile(Pressure-mechanoreceptors)) Coordination Development Between Articulators integrate new behaviors with previously stabilized ones Increase the control of individual articulator Articulators Movement Speed Decrease Performance Variability

Green Study

Three distinct developmental processes: IntegrationDifferentiationRefinement

Brain Areas in Speech Motor Control

Premotor CortexSupplementary Motor AreaPrimary Motor CortexSomatosensory CortexSupramarginal GyrusPrimary Auditory CortexHigher-order Auditory CortexCerebellumBasal Ganglia

Brain Areas in Speech Motor Control

Premotor Cortex

Supplementary Motor Cortex

Primary Motor Cortex

Somatosensory CortexSupramarginal Gyrus

Primary Auditory Cortex

Higher-order Auditory Cortex

Cerebellum

The Model of Integration Index During ofSpeech Motor Development

Plant (Jaw/ Lower Lip)

2

2 2 2

12

n

n n

Force F GDisplacement X ms bs k s s

2

3857_ ( )37.01 372.4

H Jaw ss s

2

3000_ ( )15 500

H LowerLip ss s

ControllerArtificial Neural Network

Quantitative Indices

Contribution Index

Correlation Index

1

2

0.65 0.5 0.46 0.430.27 0.32 0.4 0.43

One year old Two year old Six year old Adults

Simulation Result

Prediction of the Model

In the unnatural conditions, if the connections between motor neurons in brain stem did not develop properly for any reason, the correlation between jaw and lower lip movement would fail. However, the lower lip’s contribution is increasing while the jaw’s decreases.

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