Popular in INTRODUCTION TO COMMUNICATION DISORDERS
Popular in Language
This 7 page Class Notes was uploaded by Emily Clark on Saturday September 26, 2015. The Class Notes belongs to 1230.0 at Bowling Green State University taught by Lynne Hewitt in Fall 2015. Since its upload, it has received 20 views. For similar materials see INTRODUCTION TO COMMUNICATION DISORDERS in Language at Bowling Green State University.
Reviews for Chapter 4
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/26/15
Chapter 4 Speech Science Speech production for most individuals requires little effort The nervous system is composed of a series f complex densely connected structures that make speech and language possible The nervous system is divided into the central nervous system and the peripheral nervous system Neurons can be described by their function Efferent it conveys impulses from higher to lower structures they are also termed motor neurons Afferent brings information to a higher structure of the nervous system Neurons communicate with one another by means of synapses functional gaps between the axon of one neuron and the dendrites and cell bodies of surrounding neurons Glial cells perform a number of functions 1 they form the fatty myelin covering of axons 2 they serve as a bloodbrain barrier for nutrients delivered to neurons 3 they remove dead cells from the nervous system The CNS includes the cerebrum brainstem cerebellum and spinal cord There are differences in the size of the areas of the two hemispheres but we do not yet fully understand the functional importance of the differences Each hemisphere has four lobes Frontal responsible for motor Temporal important for auditory planning and execution processing Parietal sensory association and Occipital visual processing spatial processing The basal ganglia are important for the control of movement Damage to these structures results in involuntary movements like the tremors from Parkinson s disease or cerebral palsy The brainstem lies at the base of the brain in front of the cerebellum and includes Midbrain Pons Medulla The brainstem is the conduit for sensory information coming from the receptors of the body for touch temperature pain and pressure as well as vision hearing balance and movement The cerebellum lies in the back and on top of the brainstem Consists of two hemispheres It is important for balance Also important for ensuring coordination of various body movements specifically Timing amount and speed of movement The spinal cord lies within the vertebral column Groups of nerves extending from the CNS make up the peripheral nervous system The nerves can be divided into highly specialized cranial nerves that extend from the cerebrum and brainstem and the spinal nerves that extend from the spinal cord There are 12 pairs of cranial nerves specialized for sensory motor or sensory and motor functions The cranial nerves most important for speech production include the trigeminal facial glossopharyngeal vagus accessory and hypoglossal which innervate the musculature of the head and neck The spinal nerves are not specialized for sensory or motor functions but innervate specific areas of the body The two cerebral hemispheres are specialized in terms of the types of information they are most adept at processing Left hemisphere is specialized for sequential functioning Right hemisphere is for holistic processing The left hemisphere has a dominant role in this aspect of communicative because speech and language is processed over time The right hemisphere s holistic processing makes it more adept at face recognition comprehending and expressing emotion and music Although the two hemispheres are specialized for the types of information they are best able to handle they work together during communication The body scheme is distorted because there are a larger number of neurons that project to areas with highly developed motor skill such as the tongue and thumb Several areas of the left side of the brain are important to speech and language Broca s area it is important for the programming of movements for speech production Damage in this area causes problems in the planning and carrying out of speech movements Wernicke s area it is important for understanding auditory information and language interpretation Damage results in a marked deficit in understanding what is hear Motor activity is controlled by two major tracts of the nervous system Pyramidal o Extrapyramidal The pyramidal tract is a direct pathway from the cortical surface to the peripheral nerves Approximately 85 of the fibers traveling to the spinal nerves cross to the opposite side of the body at the medulla Therefore the left side of the body receives innervation from the right side of the brain and vice versa When an individual has a stroke in the frontal lobe of the left hemisphere most of the motor functions of the head and neck are spared This is because innervation from the right side of the brain to these nerves has not been interrupted The extrapyramidal tract is a complex system important for control movements Damage to the system results in problems with the level of background electrical activity within muscles and the development of involuntary movements such as tremors The nervous system governs speech production by providing input to the more than 100 pairs of muscles of the respiratory laryngeal and articulatory structures with continual online sensory monitoring of the process Respiration is the power source for speech production The primary components of the respiratory system are the lungs rib cage air passageways and diaphragm The internal structure of the lungs is analogous to the branching structure of an inverted tree The movement of air during breathing results from changes in lung volume and the resulting changes in air pressure within the lungs Respiration is the process of moving air in and out of the lungs Air ows from areas of high pressure to areas of low pressure Many of the tissues composing the respiratory system are elastic these structures are subject to being stretched and are capable of rebounding from the distortion As you probably have deduced by this point changes in the lung volume are accomplished by application of muscle forces to the respiratory apparatus During speech the respiratory system provides a stable air pressure within the lungs This activity is accomplished by the balancing of active and passive forces to maintain a constant pressure while lung volume is decreasing with the loss of air Speech breathing is different in two important respects from quiet breathingthe lungs are increased to a larger volume and the expiratory phase is extended Obviously if you want to shout or read a paragraph aloud without stopping to take a breath you take in more air and use a greater portion of the total volume of air in your lungs The larynx is a small hallow structure in the anterior neck The larynx is composed of cartilages muscles membranes and other connective tissue The function of the larynx in speech production is to convert respiratory energy the energy of air put into motion by movement of respiratory muscles to sound energy In speech science we are interested in the vocal folds because their vibration creates the sound of human voicing but they also serve two other vital functions They help protect the lungs from accidentally aspirating inhaling foreign matter They permit us to perform muscular actions such as bearing down The skeletal structure of the larynx consists of three large unmatched and three pairs of matched cartilages The most important for speech production are the cricoid the thyroid and the paired arytenoids cartilages Several intrinsic muscles of the larynx create the movements of the cartilages The ones that we are most interested in are the internal thyroarytenoid muscles also known as the thyrovocalis or simply the vocalis muscles The mucous membrane that lines the inside of the larynx is contiguous with the membrane of the trachea and the throat cavity Lying as they do the focal folds are subject to being moved in various ways They can be spread apart abducted or pulled together to the pint of touching adducted by the action of the muscles that move the arytenoids cartilages When the vocal folds are abducted spread apart the gap between them called the glottis is part of the open passageway that lets air ow into and out of the lungs The sound of such air movement is either very soft and quiet when the glottis is very wide harsh and noisy when the glottis is somewhat constricted Elastic recoil or myoelasticity refers to the tendency of soft tissue when deformed by some force in this case subglottal pressure to rebound to its original shape when the force is removed The more slowly the vocal folds vibrate the lower pitched the hum The faster they vibrate the higher the pitch of the hum The quality of sound produced by the vocal folds is affected by the size shape and amount of tension in the vocal folds as well as the rate and volume of air ow from the lungs No matter what a speaker s pitch is that person can change it by using the muscles of the larynx to stretch contract tense or relax the vocal folds Complex periodic sound is composed of a series of simple periodic sounds called harmonics Each harmonic tone has a unique frequency and amplitude Amplitude is represented in decibels dB of sound pressure level or intensity level When the sound of phonation travels up from the larynx and through the upper airways the sound is modulated by the size and shape of the vocal tract Articulation is the process of forming speech sounds by movement of the articulators The vocal tract is made up of a series of interconnected tubes from the larynx to the opening of the mouth and nose Articulation requires the coordinated movement of moveable structures for the production of speech sounds The articulators can be considered as fixed or mobile Fixed structures include the teeth the alveolar ridge and the hard palate Mobile articulators are the jaw tongue face and structures of the velopharynx The face is important to communication beyond the production of individual speech sounds Another mobile articulator is the mandible The mandible has the largest mass of any of the articulators and functions as a platform for the tongue The upward and downward movements of the jaw are different during chewing and speech production The tongue is perhaps the most important articulator It is composed of intrinsic muscles that allow it to change shape It can be shortened lengthened widened narrowed attened and made thicker The tongue has several identifiable parts including the root body dorsum blade and tip from back to front which are important in the description of the production of speech sounds To fully understand the production of speech We must now consider how all three systems function together to produce not only the segmental elements of speech but also the suprasegmental elements stress and intonation Speech is produced during the expiratory phase of respiration exhalation It is produced when we control the release of air from the lungs by a gradual relaxation of the inspiratory muscles using what is called a checking action Respiratory and phonation are interdependent and together permit us to modulate both pitch and loudness across a wide range of values Articulation can operate much more independently however The sourcefilter theory of speech production explains how respiration phonation and articulation operate together The respiratory system is the source of power for speech without the controlled ow of air from the lungs there would be no sound The phonatory system is the primary sound source for speech the complex periodic sound we call voicing is present in the majority of speech sounds The articulatory system is the sound filter for speech which means that the sound sources are modulated into distinctly different speech sounds in the vocal tract The airfilled cavity that is the human vocal tract behaves very much like the airfilled cavity of a clarinet Although the human vocal tract is more complex than the clarinet and can produce a wider range of different sounds The human vocal tract is different from an instrument in three main ways 1 the vocal tract can change size and shape 2 the human vocal folds can change frequency in ways instruments cannot 3 humans can generate both complex periodic voicing aperiodic fricative sounds sound sources Phonetics is the study of speech sounds At the level of the word or the phrase we created different emphases such as stress or intonation These effects are sometimes called the suprasegmental or prosodic characteristic of speech They also have created a system of syllables called the International Phonetic Alphabet that can be used to represent the segmental and suprasegmental characteristics of speech To define consonants fully four or sometimes five descriptors are typically used Voicing Are the vocal folds vibrating Nasality Are the nasal cavities contributing to the resonance of sound Manner of articulation How high is the mandible how closed is the oral cavity Place of articulation Where is the narrowest point of constriction in the oral cavity Secondary articulators Is the tongue shaped in a particular way that affects the perceptual quality of the sound e g tip curled up or sides curled down Vowels are described in a similar fashioned using three primary criteria Height How high mid or low within the oral cavity is the tongue Frontnessbackness Is the tongue positioned front central or back within the oral cavity Lip shape Are the lips spread normal or rounded Voicing is not a criteria because all vowels are considered voiced The suprasegmental characteristics of speech are produced by modulating three qualities of sound Loudness How are the volume and rate of air ow changing Pitch How is the rate of vocal fold vibration changing Duration How long is a sound being sustained The difference between two otherwise very similar sounding words is created by placing greater emphasis on either the first or second syllable of the word This emphasis is called stress A statement has an overall falling pitch while a question has an overall rising pitch Coarticulation is the simultaneous production of two sequential sounds Speakers learn throughout the years of experience listening to and producing speech that there is more than one way to produce sounds with similar acoustic signatures
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'