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Speech Production SOMAYEH SHAHSAVARANI 90/1/29 Language Speech Painting Language Writing Signing 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 Types controller 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 Production Plant Articulation Phonation Respiration Speech Production Plant 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 Production Learning Speech Motor Development Speech production is a developmental process. 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: Integration Differentiation Refinement Brain Areas in Speech Motor Control Premotor Cortex Supplementary Motor Area Primary Motor Cortex Somatosensory Cortex Supramarginal Gyrus Primary Auditory Cortex Higher-order Auditory Cortex Cerebellum Basal Ganglia Brain Areas in Speech Motor Control Supplementary Motor Cortex Primary Motor Cortex Somatosensory Cortex Premotor Cortex Supramarginal Gyrus Higher-order Auditory Cortex Primary Auditory Cortex Cerebellum The Model of Integration Index During of Speech Motor Development Plant (Jaw/ Lower Lip) n2 Force F 1 2 G 2 Displacement X ms bs k s 2n s n2 3857 H _ Jaw( s ) 2 s 37.01s 372.4 H _ LowerLip ( s ) 3000 s 2 15s 500 Controller Artificial Neural Network Quantitative Indices Contribution Index 1 2 One year old Two year old 0.65 0.27 0.5 0.32 Six year old 0.46 0.4 Correlation Index Adults 0.43 0.43 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. Thank You