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THE LISTENING CHILD: What Can Go WrongWhat all parents and teachers need to know about the struggle to survive in today's noisy classrooms
By STEPHEN V. PRESCOD
Trafford PublishingCopyright © 2012 Stephen V. Prescod
All right reserved.
Chapter OneHow We Hear
The Development of the Ear
The human ear is fully functional by the thirty-sixth week of gestation. By this time, the cochlea (end organ of hearing) portion of the bony labyrinth situated in the anterior aspects of the inner ear has become sophisticated in distinguishing sounds. The manner in which it analyzes sounds is somewhat restricted at this stage, however, due to lack of the maturation of the central auditory nervous system. But even then, there is evidence to suggest that "selective listening" of the fetus has already begun; that is, the fetus is already processing incoming stimuli and making distinctions between, for example, the mother's voice and other voices it hears (Kolata, 1984).
It is also believed that an unborn child, still protected in its mother's womb, is capable of responding to certain sounds long before it is born. Researchers have found that if a loudspeaker is placed near the mother's womb, a startled reflex to loud sounds can be elicited from the unborn child. It is here that the environmental enrichment begins to play an indispensable role in the child's capacity for discriminative and refined listening. As a matter of fact, there is no period of parenthood with a more formative effect on development of the child's brain than the nine months of pregnancy leading to birth.
By the time, the baby is born the external ear (auricle) is formed and continues to develop until around age nine. The middle ear is also formed and effectively pneumatized (supplied with air pressure). The bones of the middle ear (ossicles) are already developed. The tympanic membrane (eardrum) changes relative position during the first two years of life while the inner ear is fully operative by the end of this two-year period. With a functional ear in place, the child is fully equipped to embark on the fascinating voyage of speech and language acquisition through the perception of sound. After birth, hearing enables a child to spin a web of language during his or her early growth and development. The development of listening skills starts at a very early age, and for a good reason, since it is by listening effectively through normal hearing processes that the child develops adequate speech and language function. That is because speech development is directly linked to hearing. A child who has difficulty hearing will naturally have difficulty acquiring appropriate speech patterns because all humans learn to speak by first hearing.
In order for the child to effectively process information he or she hears, both the receptive (decoding) and the perceptive (encoding aspects of hearing must be in perfect synchrony. Actually, the ear depends quite heavily on normal reception in hearing in order to transmit the correct signals it receives to the brain for cognitive processing.
As signals reach the brain and meaning is attributed to them, perceptive aspects of hearing or listening is at work. If anything is negatively affecting the receptive apparatus of hearing (the physical mechanism of the ear), the brain will be limited in its ability to process information it receives accurately. An infant who is developing proper listening skills, therefore, is not in a passive stage of development at all, but he or she adapts to the challenges of the listening environment and is involved in the profoundly dynamic and energetic undertaking, requiring the highest active capabilities (Friedlander, 1970).
The Hearing Mechanism
Technically, hearing actually takes place at the brain level and not at the ear level as is commonly assumed. The proper function of the ear is to change sound waves entering it into electrical signals (neural impulses) that the brain can understand. Sound waves enter the outer ear, pass through the auditory canal, and beat against a tightly stretched membrane called the eardrum (tympanic membrane) causing it to vibrate. The vibrations are picked up by three tiny bones (the tiniest bones of the body) housed in the pea-sized middle-ear cavity. These bones of the middle ear transmit the vibrations to the fluid-filled chamber of the inner ear via the stapes footplate.
Inside the fluid-filled chamber of the inner ear are thousands of specialized cells, each equipped with many microscopic hairs. These hair cells are immersed in the fluid that fills the inner ear chamber. They are set in motion whenever the fluid is disturbed. Stimulation of the hair cells by the disturbed fluid, in turn, generates electrical impulses that are sent on to the brain for decoding.
Hence, in order for a sound wave to reach the brain, the ear must first transform it into an appropriate medium that can be interpreted and understood by the brain. That appropriate medium is the neural impulse. It is the movement of the fluid in the inner ear that stimulates the attached cells to send a train of tiny neural impulses along the auditory nerve to the brain, where we eventually perceive them as sound. When any part of the hearing (receptive) mechanism cannot do its job efficiently, the transmission of sound to the brain is affected and the signals reaching the brain are not properly decoded. This results either in a hearing loss or a misrepresentation of the information received.
A delay in signal transmission to the brain caused by hearing loss or any other adverse listening condition in the environment, such as noise, causes the signal transmission to pick up distortion. The distortion can be created by a delay of just a few milliseconds in the temporal ordering of auditory symbols. The problem with the temporal ordering of language patterns brought on by even such a brief delay is that the delay causes the incoming impulses arriving at the brain to reach the brain out of phase or out of sequence with each other seriously restricting activity on the part of the child to attribute meaning to what he or she hears.
This has important implications for the function of the receptive processes of all children in general, but for those with central auditory processing disorders (CAPD) in particular. It is on the efficient transmission of stimuli to the brain that children depend for the acquisition of language, interpersonal communication, and learning. When this is affected, it creates processing difficulties forcing the child with CAPD to respond inconsistently to sound, causing him or her to be invariably misclassified as unintelligent, hearing-impaired, or mentally deficient.
Delayed signals arriving at the brain level out of phase are not clear, clean, or decipherable, and the brain cannot decode them efficiently. Under normal conditions, the brain processes information in milliseconds. But when the neural transmission to the brain has been altered in any way by unfavorable listening conditions such as noise, ear infection with middle ear fluid, emotional disturbance, or permanent hearing loss of the inner ear, the brain is unable to process incoming information with the speed and efficiency needed to generate understanding. When this occurs, the child then fails to maintain proper intellectual functioning known as useful auditory perceptual behavior. Indeed, any one of the hearing conditions listed below in this chapter can contribute to such auditory perceptual failure and seriously restrict comprehension.
Hearing loss is one of the limiting factors affecting how information is processed by the brain as well as how language is acquired by the child. It is one of the most serious and least recognized disabilities in children. The most critical years for detecting hearing loss are the preschool years and the lower elementary grade levels. Undetected and untreated hearing loss can have lasting effects on early speech and language development, learning, social growth, and the overall emotional stability of the child.
Even a minor hearing loss that is undetected can affect a child's academic and social development over time. Poor hearing is one of the most common undiagnosed problems responsible for children's learning difficulties. It is not unusual for a child in such circumstances to be classified as mentally challenged, slow, inattentive, dull, and antisocial simply because he or she does not perform academically on par with his peers or participate in social activities like the rest of them.
What is tragic is that children often conceal the harsh reality that they are unable to participate because of defective hearing. In Ontario, as many as one in four preschoolers has a communication disorder or significant language delay. At least, 6 percent of the total school population from junior kindergarten to grade 12 is affected (CASLPO, 2001).
Studies has shown that if left undetected and untreated, even a mild hearing loss can reduce a child's academic achievement and cause educational retardation and deprivation
cause the child to be falsely labeled as inattentive and speech delayed
increase behavioral problems, causing social isolation, and accompanying psychological and emotional disturbance
cause permanent hearing loss if untreated for an extended period of time.
Children with early language-processing difficulties are ten times more likely to have associated behavioral problems than those without such difficulties. It has been shown that 60 percent of children with behavioral disorders have significant language problems and a further 75 percent to 80 percent of students with learning disabilities have related language problems (OSLA, 1996). Hearing loss is crucially linked to impaired language development. Since speech develops as a direct consequence of hearing, children with hearing impairment experience difficulty developing normal speech along with delays in other aspects of academic functioning. The most likely results include the following:
Academic delays especially in reading and mathematical concept formation.
A 43 percent drop-out rate compared to 23 percent in nonimpaired children.
Consistent rating and labeling of children with language disorders as nonintelligent and academically slow.
Falling behind in school—children with mild to moderate hearing losses perform 1 to 4 grades behind peers with normal hearing.
Low educational levels (children with severe to profound hearing losses generally achieve no higher than third or fourth grade level, unless early and appropriate intervention have been implemented).
Prolonged absence of normal stimulation to the cochlea because of ear infection or hearing loss can and does produce an altered abnormal physiological response to auditory signals reaching the brain for processing. The prolonged absence of normal stimulation creates what is known as auditory sensory deprivation. Auditory sensory deprivation alters the quality of the signal reaching the brain for processing as action potentials (neural discharges) to the brain are blocked. A deprivation of input means that the neurological processes by which this child learns will be altered.
A defective hearing apparatus will most certainly distort those signals that are changed into neural impulses for the brain to use. This impedes learning because the information conveyed through the peripheral mechanism, namely, the ears, is disrupted by hearing loss, and the central auditory nervous system is not able to use the information received, since it is highly distorted from the impaired ear.
When signals or neural impulses are distorted, the brain is forced to process distorted signals, and it is these signals that are reinforced by the child over and over again, becoming established patterns of communicative behavior, until the child, through proper training and therapy, is in a position to correctly display behaviors that are acceptable. Therefore, the earlier a hearing loss is detected and treated, the better the chances that the treatment will be effective and that associated problems in communication will be less severe.
Some children are born with defective hearing while others lose hearing abilities because of an illness or accident. In either case, the earlier the diagnosis and treatment, the better the prognosis for successful communication and the more the child can rely on the auditory channel for efficient transmission of information to the brain. It is for this reason that the Joint Committee on Infant Hearing, 1990 Position Statement endorsed the goal of universal detection of infants with hearing loss as early as possible. It recommends that all infants with hearing loss be identified before three months of age and receive intervention at least by six months of age.
Since it has been shown that hearing loss has significant implications for the normal development of speech perception, cognitive, psychosocial skills, and overall academic achievement early identification cannot be overemphasized. The design of comprehensive intervention strategies that address the overall development of not merely language but the academic, psychosocial, and developmental communicative experience of the child is of prime importance (Johnson, 2001).
Types of Hearing Loss
Let us now examine some of the things that can go wrong with the receptive apparatus of hearing and the ways in which they may influence the child's ability to process information normally. There are four different types of hearing conditions that may result from a malfunctioning hearing apparatus and, therefore, limit the scope of decoding capabilities of the brain—conductive hearing loss, sensorineural hearing loss, mixed hearing loss, and central hearing loss (which will be dealt with separately in Part II of this book). Any or a mixture of these conditions can affect the way a child's brain processes information.
A conductive hearing loss is a loss of hearing caused by blockage of sound waves reaching the inner ear. This blockage reduced mechanical movement in the outer and middle ear, causing a conductive hearing loss. In most cases, early detection and treatment of a conductive hearing loss enable prevention of further impairment of the hearing apparatus. Transmission of sound waves may be blocked by damage or malformation of outer and middle ear structures. It is important to note that as long as this occurs sound will not be transmitted efficiently to the brain, and all sound entering the ear will be weaker, delayed, and distorted to some degree as it arrives at the brain for processing.
Occasionally, the outer ear may be incompletely formed, resulting in partial or complete blockage. This condition can be treated by surgical means by simply widening the existing canal or by opening a new canal if the passageway is completely blocked. In any event, a hearing loss usually results from conditions of this kind until the situation can be surgically treated.
Another condition that may affect the outer ear canal is the accumulation of wax, which prevents effective sound transmission from reaching the eardrum. Periodic removal of wax by a qualified practitioner will solve this problem by professionally removing the wax from the ear.
Finally, the outer ear may be infected by disease causing redness, irritation, and rawness of the skin tissues that line the canal walls of the ear. This condition is referred to as external otitis and is usually amenable to medication
The middle ear (or tympanic cavity as it is called) is an air-filled cavity or chamber. Air pressure is necessary for the general good health of the middle ear and for its proper function. The middle ear consists of the eustachian tube, mastoid antrum, and mastoid air cells. They are jointed together to form a continuous air space. It is the eustachian tube that constantly maintains the equilibrium between the middle air pressure and the external air pressure.
Allergies, colds, and ear, nose, and throat infections occasionally cause the eustachian tube to close, thus upsetting the delicate equilibrium in pressure balance between the middle ear and external ear and causing fluid to build up in the middle ear space. The accumulation of fluid is called serous otitis media (SOM). Serous otitis media usually follows a cold and also occurs as the residual condition of acute otitis media, particularly when antibiotic therapy has been ineffective.
The eustachian tube connects the middle ear cavity with the back of the throat. The upper end of the tube is normally kept open while the lower end is normally closed or collapsed because it is surrounded by soft tissue. Childhood diseases, such as upper respiratory and subsequent middle ear infection and closure of the eustachian tubes by enlarged adenoids, are among the known causes of middle ear problems that can result in conductive hearing loss. In the case of enlarged adenoids, for example, the eustachian tube opening may become blocked, leading to infection of the middle ear cavity. When tonsils and adenoids are infected in this manner, a physician decides what course of action or treatment would be most effective in resolving the problem.
Excerpted from THE LISTENING CHILD: What Can Go Wrong by STEPHEN V. PRESCOD Copyright © 2012 by Stephen V. Prescod. Excerpted by permission of Trafford Publishing. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents
About the Author....................xvii
Introduction: How Processing Works within the Child's Classroom - An Overview....................1
Chapter 1: How We Hear....................5
Chapter 2: The Child's Speech and Hearing Development....................17
Chapter 3: What to Do About a Child's Hearing Impairment....................35
Chapter 4: The Role of the Ear in Processing....................43
Chapter 5: The Child Who Does Not Understand....................53
Chapter 6: The Child Who Forgets....................63
Chapter 7: The Child Who Is Disorganized and Confused....................69
Chapter 8: Noise And The Mind Lost In The Classroom....................75
Chapter 9: The Causes of Central Auditory Processing Disorders (CAPD)....................79
Chapter 10: Help Is Available....................89
Chapter 11: Clinical Cases....................103
Chapter 12: Teaching Success with Children Having CAPD....................117
Answers to Self-Evaluation Quiz....................169