S peech D evelopment

1. Speech Development Professor: Dr. F. Towhidkhah Student: S. Shahsavarani First Semester 2008-2009

2. Outline: 1- Introduction 2- Some Novel Works on Speech Development 3- Articulatory Adaptation 4- Sensory Motor Coupling 5- References Human Motor Control Course First Semester 2008-2009

3. Outline: 1- Introduction 2- Some Novel Works on Speech Development 3- Articulatory Adaptation 4- Sensory Motor Coupling 5- References Human Motor Control Course First Semester 2008-2009

4. Introduction Motor Neuron Pools The groups of neurons lying in the BRAIN STEM or spinal cord that innervate a single muscle… In the brain, the concepts and units of language must ultimately be translated into motor system variables. When humans speak, we produce sentences, phrases, words, and syllables that listeners understand. In order for people to speak, the brain must generate motor commands to control activation of many different motor neuron pools. These motor neuron pools include those innervating muscles of the articulators, the larynx, and the chest wall. Human Motor Control Course First Semester 2008-2009

5. Introduction Articulators Chest Wall Larynx Learning Brain Stem Speech Muscles Motor Speech Region Language Units Adaptation Motor Commands Motor Neuron Pools Sentences phonemes phrases Words Human Motor Control Course First Semester 2008-2009

6. Outline: 1- Introduction 2- Some Novel Works on Speech Development 3- Articulatory Adaptation 4- Sensory Motor Coupling 5- References Human Motor Control Course First Semester 2008-2009

7. Some Novel Works on Speech Development Research Groups in Development of Speech Speech Motor Development Drs. Anne Smith Department of Speech, Language, Hearing Sciences, Purdue University, USA Stuttering development of speech production The Physiologic Development of Speech Motor Control Jordan R. Green Department of Communicative Disorders University of Wisconsin, USA His research projects are designed to identify the motor skills that are essential for normal speech and feeding development, to understand how various neurologic impairments affect speech and swallowing, and to develop innovative methods for studying speech motor performance. Human Motor Control Course First Semester 2008-2009

8. Some Novel Works on Speech Development Computational Model in Development of Speech DIVA Model (Directions In to Velocities of Articulators) Prof. Frank H. Guenther Department of Cognitive and Neural Systems, Boston University,1994 Sensorimotor Coupling Model Dr. Gert Westermann Oxford University Developmental Cognitive Neuroscience Development of speech sounds in infancy Eduardo Reck MirandaProfessor in Computer Music University of Plymouth, United Kingdom His research is aimed at understanding how and why people create, perform and listen to music. Human Motor Control Course First Semester 2008-2009

9. Outline: 1- Introduction 2- Some Novel Works on Speech Development 3- Articulatory Adaptation 4- Sensory Motor Coupling 5- References Human Motor Control Course First Semester 2008-2009

10. Articulatory Adaptation (Jordan R. Green) • Speaking is among one of the most complex motor acts performed by humans. It requires co-ordination of 70 muscles serving the respiratory, laryngeal, and vocal tract systems. Moreover, speech is produced at a remarkably fast rate, approximately fifteen sounds per second. • Children typically do not master the sounds of their language until 8 years of age, and some features of speech do not exhibit adult-like consistency until adolescence. • In early speech, the probability that a sound will be correctly produced depends on the match between existing coordinative capabilities and those required by each sound. • Young children challenged by their limited options for producing different sounds are obligated to adopt strategies for approximating adult-like speech. Human Motor Control Course First Semester 2008-2009

11. Articulatory Adaptation (Jordan R. Green) • These early articulatory adaptations provide a window into the developmental status of the neuromotor system and cognitive/perceptual processes. • Careful study of these behaviors is providing new insights into the many processes involved in learning to speak. • Unlike other motor systems (e.g., reaching, locomotion), the developmental course of articulation is largely unknown, although it is a matter of fundamental importance for understanding the physiologic basis of both typically and disorder speech development. • Research in speech motor development has been slowed by the absence of methods for obtaining physiologic measures of articulation in young children. Human Motor Control Course First Semester 2008-2009

12. Articulatory Adaptation (Jordan R. Green) Bilabial Consonants A speech sound produced by using both lips: in English, b, p and m are bilabials. Lip and Jaw Coordination (EXPERIMENT) Productions of syllables containing bilabial consonants were observed from speakers in four age groups (i.e.,1-year-olds, 2-year-olds, 6-year-olds, and young adults) A video-based movement tracking system was used to transduce movement of the upper lip, lower lip, and jaw. The coordinative organization of these articulatory gestures was shown to change dramatically during the first several years of life and to continue to undergo refinement past age 6. Human Motor Control Course First Semester 2008-2009

13. Articulatory Adaptation (Jordan R. Green) Lip and Jaw Coordination (EXPERIMENT) Human Motor Control Course First Semester 2008-2009

14. Articulatory Adaptation (Jordan R. Green) • In summary, one result that has emerged from these experiments on early speech development is that co-ordination of mandible precedes that of the lips. The findings also suggest that the young child has a limited ability to independently control the upper and lower lips. These constraints in early articulatory co-ordination and control have predictable consequences on infants’ sound producing capabilities and may explain why children with differing experiences acquire early sounds in a similar order. • These findings probably reflect extensive changes in the biomechanical composition of vocal tract structures and their neuromotor pathways. Conclusion Human Motor Control Course First Semester 2008-2009

15. Outline: 1- Introduction 2- Some Novel Works on Speech Development 3- Articulatory Adaptation 4- Sensory Motor Coupling 5- References Human Motor Control Course First Semester 2008-2009

16. Sensory Motor Coupling(Gert Westermann,Eduardo Reck Miranda) • In recent years there has been mounting evidence that the pre-linguistic period plays a major role in the development of phonology. It is often hypothesized that the first speech-like articulations and the babbling phase between 5 and 10 months of age allow infants to develop a link between articulatory settings and the resulting auditory consequences. • More recent evidence suggests that this link is learned rather than innate, focusing on evidence for the role of babbling in normal speech development. It has been found that deaf infants do not babble normally, indicating the role of audition for normal babbling, and that they subsequently often do not develop intelligible speech. Infants that were prevented from normal babbling due to tracheotomy likewise show abnormal patterns of vocal expressions that persist. Human Motor Control Course First Semester 2008-2009

17. Sensory Motor Coupling(Gert Westermann,Eduardo Reck Miranda) A Computational Model This model learns a coupling between motor parameters and their sensory consequences in vocal production during a babbling phase. Co-variance Learning Rule Human Motor Control Course First Semester 2008-2009

18. Sensory Motor Coupling(Gert Westermann,Eduardo Reck Miranda) One input to a map will typically activate several units, and the response to an input x , that is, how the neural map “perceives” that input, is computed in a population code: the response is the vector sum of the positions of all units, weighted by their activation values: where is the position of unit i , and is its activation. Such population codes have been found to play a role for example in the encoding of motor commands in the monkey cortex. Human Motor Control Course First Semester 2008-2009

19. Outline: 1- Introduction 2- Some Novel Works on Speech Development 3- Articulatory Adaptation 4- Sensory Motor Coupling 5- References Human Motor Control Course First Semester 2008-2009

20. References: 1- Jordan R. Green, Christopher A. Moore, “The Physiologic Development of Speech Motor Control: Lip and Jaw Coordination”, Department of Speech and Hearing Sciences University of Washington, 2000 2- Gert Westermann, Eduardo Reck Miranda, “Modeling the Development of Mirror Neurons for Auditory-Motor Integration”, J. New Music Research, 2002 3-Gert Westermann, Eduardo Reck Miranda, “A new model of sensorimotor coupling in the development of speech”, J. Brain and Language, 2003 4- Anne Smith, “Speech Motor Development: Integrating muscles, movements, and linguistic units”, J. Communication Disorders, 2006 Human Motor Control Course First Semester 2008-2009

21. Thank you very much! Any question? Human Motor Control Course First Semester 2008-2009