Excerpted from Children with Disabilities, (pp. 275-292), Fourth Edition, edited by Mark L. Batshaw, M.D. Baltimore: Brookes Publishing, http://www.brookespublishing.com. Copyright 1997 by Paul H. Brookes Publishing Co. Reprinted with permission. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
7 x 9-1/4
Upon completion of this chapter, the reader will:
- be able to describe the different elements of speech and of language
- understand the typical course of language development
be familiar with the biological processes that underlie speech and language
- know the major types of speech and language disorders and their causes
- be aware of the methods of speech and language assessment
- recognize the treatment alternatives for these communication disorders
Parents, biologists, and philosophers all recognize that language, more than any other skill, differentiates humans from other animals. In fact, children’s language development often is used as a gauge of their more general development, and many referrals for developmental evaluation start with the parents’ concern about their child’s language skills. Conversely, many developmental disabilities (including mental retardation, autism, learning disabilities, and cerebral palsy) result in some impairment of language or speech skills. In this chapter, the nature of speech and language, their typical course of development, commonly seen deviations from that typical course, and methods of diagnosis and treatment for disorders of communication are discussed.
Language and Speech: Two Sides of a Coin
Language and speech, together, allow people to communicate through the medium of sound. Speech refers to the sounds that we use to transmit ideas from one person to another. Language refers to the code that gives meaning to the sounds, telling us that specific sounds mean specific things and indicating what order the sounds should be in. People from different countries use different codes (i.e., they use different languages). Some codes are visual rather than acoustic (e.g., American Sign Language), bypassing speech entirely. So, communication can occur without speech, but it would be very limited without language.
The Domains of Language
Both speech and language have component parts. The components of language are phonology, grammar, semantics, and pragmatics. The first two domains, phonology and grammar, give language its form. The phonology of a language is the distinct set of sounds that it employs and the rules for using those sounds. For example, Spanish and English share many sounds, but English does not use the trilled r, and Spanish does not use the ng. The grammar of a language specifies how the different words and parts of words are arranged. In English, for example, we put the plural “s” at the end of the word, and we put adjectives before the nouns they modify. In Spanish, however, plurals are formed similarly, but adjectives go after the noun.
The semantics of a language tell us what the different words mean: In English, soo is a female name (Sue), but in Spanish, soo means “his,” “her,” or “your” (su). Semantics thus gives language its content. Finally, the pragmatics of a language describe how language should be adapted to specific social situations, to convey emotion, and to emphasize meanings. Discourse and narrative skills (conversational turn taking, organizing a story, etc.) and prosody (the use of pitch, rhythm, and stress) are included in this domain. A spellbinding storyteller is one of the best illustrations of the masterful use of pragmatics.
The Domains of Speech
Speech is commonly characterized along four domains: articulation, resonance, voice, and fluency/rhythm. The most familiar of these is articulation, the production of consonant and vowel sounds by the lips, tongue, and teeth. Resonance refers to the balance of airflow between the nose and the mouth. The consonant sounds m, n, and ng require air to flow through the nasal tract, and disorders of resonance cause either a hypernasal or hyponasal sound.
The vibration of the vocal cords in the larynx yields the speech quality known as “voice.” Disturbances in laryngeal control can cause the voice to be unusually high, deep, or hoarse. The fourth domain of speech is fluency. Typical fluency entails a certain rate and rhythm. Disorders of fluency, often known as stuttering, disrupt that rate and rhythm.
Language Development: A Commonplace Miracle
Language is the most complex skill that people acquire. Unlike calculus, abstract painting, chess, or many other very difficult skills, no animal or machine has ever been able to “do” language like people do. And yet, despite the complexity of language, the vast majority of people develop from nonverbal, noncomprehending infants to become fluent and skilled listeners and talkers. Although science does not yet understand how children acquire language so well, it is known that children from all cultures appear to follow the same general course of language development.
Even before they are born, children begin to learn about the sounds of their native language. Psychologists have found that very young infants can distinguish between a foreign language and the language their mothers spoke to them in the womb. In the first few months after birth, children further tune their ears to the specific sounds used in their language (its phonology) and start shutting out foreign sounds (Werker & Tees, 1992). That is why, later in life, we often have difficulty hearing just how foreign words are pronounced. Parallel with these receptive skills, children begin developing their expressive skills. Social smiling is regarded as one of the first expressive milestones, followed by cooing (using the voice box) around 2 or 3 months of age. Starting around 6 months, infants use their oral articulators to babble consonant sounds. Infants who are “spoken” to in sign language also babble around that time–with their hands (Petitto & Marentette, 1991)!
In the second year of life, semantic development usually comes to the fore. Although “mama,” “dada,” and a few other words may be used earlier, vocabulary acquisition does not really accelerate until around 1-1/2 years. Between then and 2 years old, children seem to figure out that everything has a name, and they may expand their vocabulary by many words each day. They demonstrate their new vocabulary both by speaking the words and by pointing to or retrieving things that are requested. When children learn new words, they often show overgeneralization (e.g., calling all animals “doggie”) or undergeneralization (e.g., using the word “dog” for their own pet but not realizing that other canines also are “dogs”). Most utterances during this period consist of single words, though this is also the time that children produce profuse jargon, a form of speech that mimics the intonation of real language but does not use real words or carry meaning.
In the third year, semantic ability continues to develop with the emergence of grammar taking center stage. Now, children begin to speak in phrases–two words at first (“more milk”), followed by longer and longer phrases (“Daddy go bye-bye car”). Later in the year, children start to utter full sentences; use pronouns correctly; and use prepositions, plurals, and verb conjugations (e.g., sleep-ing). Psychologists have found that children who speak a single language typically gain mastery of these morphemes in a specific order. In English, for example, “-ing” is learned, followed by “-s” and then “-ed.” And again, overgeneralizations (e.g., “runned” instead of “ran”) may be produced before final mastery of all the correct forms occurs.
During the preschool years, children continue to acquire vocabulary and to produce more complex grammatical constructions. By the time children reach early school age, they already have become masters of their native language, capable of understanding and producing almost all the grammatical constructions that adults use. These preschoolers also acquire the pragmatics of language, learning how to alternate turns during conversation, how to tell a cohesive story, and how to modulate the tone and pitch of their speech to match their conversational partners. When speaking to younger children, for example, preschoolers will spontaneously slow down their speech, overemphasize their enunciation, and repeat words frequently (Shatz & Gelman, 1973). Put another way, they speak “motherese” to younger children.
Not all children strictly adhere to the pattern of language acquisition outlined in the preceding paragraphs. For example, some children may start speaking in short phrases, rather than with single words (Bates, Bretherton, & Snyder, 1988). The age at which children achieve specific language milestones also varies. But for most, the age at which the first word is spoken (or the age for other milestones) has little bearing on later academic performance. Perhaps more surprisingly, the ages at which these milestones are reached are only minimally related to the environment in which the child is raised. Whether both parents work or the child attends child care, most children show remarkable resilience in their language development. Attesting to this is the fact that almost all adults speak grammatically and with a vocabulary of tens of thousands of words, despite the wide variations that exist in child-rearing environments. (For a general review of language acquisition and of introductory linguistics, see Burling, 1992.)
The Biological Basis of Language: Ears to Brain to Lips
What are the mechanisms that underlie this uniquely human skill? How are we all able to master such complex behaviors as language and communication, when the fastest, most powerful computers still cannot understand human speech? The answer is that the human brain is a wonderfully complex biological machine. Although we are far from a full understanding of its workings, we know that a rich network of neurons distributed widely across different brain regions is devoted to the processing of language.
Ears and Auditory Pathways: Antenna and Tuner
In contrast to the sound made by a tuning fork or even the sound made by an orchestra, the sounds of speech are extraordinarily complex. Acoustically, human speech features multiple sounds that occur simultaneously across many frequencies, with rapid transitions from one frequency to another (Figure 13.1). The ear must tune into this complex auditory signal, decipher it, and translate it into electric impulses. These impulses are then sent by nerve cells to the auditory areas of the cerebral cortex, which lie in the brain’s temporal lobe (see Chapter 14). The primary auditory cortex then processes the impulses further, passes them along to language areas of the cortex, and probably stores a version of the acoustic signal for a brief period of time. Dysfunction in any of these steps can interfere with the comprehension of language.
Brain: A Neural Network for Understanding
How does the brain take these processed acoustic signals and interpret them into thoughts and concepts? The starting point is in the areas that surround the primary auditory cortex. This region, known as Wernicke’s area, is believed to recognize the pattern of the auditory signals. For each different signal (i.e., for every different word), a distinct set of neurons becomes activated (Figure 13.2). Thus, when a person hears the word “cup,” auditory pathways transmit the signal to Wernicke’s area, where neurons that correspond to the sound kup become activated. These neurons then activate other neurons (perhaps in the inferior temporal lobe) that store a visual picture of a cup and still other neurons (perhaps in the parietal lobe) that store concepts about how cups are used. According to this model, a person’s knowledge (auditory, visual, and conceptual) about “cup” is stored in a neural network that encompasses many brain regions, not in a single central processing unit (Damasio & Damasio, 1992).
When we think a thought and then try to verbalize it, a reverse process is believed to occur. For example, if a person was asked to describe a cup, he or she would first activate an internal representation of a cup, including its shape, its uses, and related concepts (glass, saucer, liquid, drinking, spilling, etc.). Then, these thoughts would be channeled through a speech area of the brain, known as Broca’s area, in the inferior frontal lobe. Broca’s area is believed to be responsible for somehow converting these thoughts into the patterns of neuron activation that are needed to produce speech. Another theory, that is compatible with newer neural network models, suggests that Broca’s area may also participate in the perception of sounds as well as the production of speech. This “motor theory of speech perception” is supported by some studies using functional neuroimaging techniques (Liberman, Shankweiler, Fischer, et al., 1974; Zattore, Evans, Meyer, et al., 1992).
Lips and More: Speech Output Devices
Like the other aspects of communication, the act of speech production is terrifically complex. After all, the lips alone cannot speak; they must be coordinated with the tongue, palate, jaw, larynx (which itself has many muscles), and even the diaphragm. In sum, the coordination of the motor apparatus used for talking is considerably more difficult than the coordination of the muscles needed for walking. Conditions affecting motor planning and control, such as cerebral palsy, can thus cause impairments in speech output.
Other Biological Considerations
Studies of adults who have had strokes have provided much of our knowledge on how the brain handles language (Damasio & Damasio, 1989). For example, strokes in Broca’s area cause impairment in language output, and strokes in Wernicke’s area cause difficulties in language comprehension. It also is known that strokes in the left hemisphere of the brain cause language impairment much more often than strokes in the right hemisphere. It is estimated that the left hemisphere is dominant for language in about 90% of the population. The right hemisphere does contribute to language processing, however, especially to aspects of pragmatics (Code, 1987). Research also suggests that adult women may show less rigid left-right specialization than men (Shaywitz, Shaywitz, Pugh, et al., 1995).
In addition to Broca’s and Wernicke’s areas, other brain regions, including the auditory and motor control areas, participate in language function. Also involved are the brain regions that are responsible for memory. Memory function is essential for remembering the thread of a story, for recalling who a pronoun refers to, and for processing lengthy and complex sentences (e.g., “The boy who the girl with the ponytail hugged is crying”) (Just & Carpenter, 1992).
Finally, it is important to remember that the brain is a dynamic organ that constantly adapts to new information. As a result, the areas of the brain that serve language differ at least slightly from one person to the next and even from one language to the next in people who are multilingual (Ojemann, 1991). Furthermore, it is not known whether the adult language areas are the same as those areas used by children to acquire language (Thal, Marchman, Stiles, et al., 1991). It is possible that some parts of the brain are used only during the period of language development, but not later, just as training wheels may be used to learn how to ride a bike but are not used later on. It is clear that the young brain shows more plasticity and adaptability than the adult brain. As a result, children recover more readily from brain injuries than do adults, whether language or other areas are injured. (A more extensive review of the brain basis of language and speech is provided by Damasio & Damasio, 1992.)
Speech Disorders and Their Causes
Speech disorders affect the ability to produce speech but not the ability to express or to understand language. They may involve any of the previously discussed components of speech, and they may occur as isolated speech problems or together with language and other developmental disabilities (Ruscello, St. Louis, & Mason, 1991; Van Dyke, Yeager, McInerney, et al., 1984). Estimates of the prevalence of speech disorders vary from one study to another, depending on the populations screened, the methods used for screening, and the precise definitions or levels of impairment used as diagnostic criteria. One study, a very comprehensive screening conducted in urban and suburban Canada, found evidence for pure speech disorders in about 6% of boys and girls in kindergarten. Another 3%-8% had both language and speech disorders (Beitchman, Nair, Clegg, et al., 1986).
Articulation problems are much more common than disorders of voice, resonance, or fluency. As anyone who has played with toddlers knows, children typically go through a developmental progression in their articulation skills. Some sounds are correctly pronounced before other sounds, for example, the “b” sound before “t” and “sh.” As a rule of thumb, 1-year-olds are 25% understandable by non-family members, 2-year-olds are 50% understandable, and 4-year-olds are 100% understandable. Most children with impaired articulation have no known cause for their problems, but hearing impairments should be considered when there are multiple articulation errors. In children who are “tongue tied,” movement of the tongue is restricted by an extremely short frenulum, which is the band of tissue connecting the underside of the tongue to the floor of the mouth. Although this condition can cause articulation problems, it does not cause language delays, and the articulation problems are usually treatable without surgery.
Disorders of resonance occur when the soft or hard palate is dysfunctional. Cleft palates cause an obvious problem in the regulation of airflow between the mouth and the nose. Some children without obvious clefts also can have palatal dysfunction, with consequent hypernasality. An example is found in children with velocardiofacial (VCF) syndrome. These children may have either overt cleft palates or “submucus clefts,” in which the palate appears to be intact, but the underlying muscles are cleft and do not work properly. Hyponasal speech can be encountered in children with nasal obstruction, which can result from chronic allergic congestion, septal deviation in the nose, enlargement of the adenoids, or from other causes.
Voice disorders (abnormalities in pitch, loudness, softness, and hoarseness) usually result from some sort of injury to the laryngeal apparatus. Possible causes of injury include viral infection (causing laryngitis), polyps on the vocal cords (which also are caused by viruses), and abusive vocal patterns (e.g., excessive shouting, deliberate alterations of pitch). Neurological injuries can cause paralysis of one or both sides of the voice box, with resultant abnormalities of pitch, loudness and, possibly, voice quality (hoarseness).
Stuttering is a general term that refers to abnormalities in the fluency and rhythm of speech. These dysfluencies can take the form of unusual hesitations or pauses, repetition of words or syllables, and the interjection of nonspeech sounds. Typically developing children and adults often have some dysfluencies, but they are not psychologically upset by these dysfluencies as stutterers are. No underlying anatomical or physiological defect has been identified definitively, but dysfluency can have more pervasive and devastating psychological consequences than other speech disorders. The early identification of a significant dysfluency and careful efforts to encourage the child’s confidence in his or her speaking ability are central to the successful treatment of stuttering (Leung & Robson, 1990).
Dysarthria and Dyspraxia
Dysarthria refers to dysfunction in the neuromotor control of the muscles used for speech. It may occur either in isolation or as part of a general condition such as cerebral palsy or traumatic brain injury (TBI). Articulation is most often affected, although resonance, voicing, and other components of speech may be affected as well, depending on the particular muscles involved. Dyspraxia is a somewhat similar condition in which voluntary but not reflexive control of muscles is impaired. Here, too, articulation is commonly affected (Aram & Horwitz, 1983). The precise neurological mechanisms of dyspraxia are unknown, though it may follow TBI. The term developmental apraxia is also used to refer to these conditions.
The most common congenital malformation affecting the jaw region is cleft lip and palate. These defects occur when the palatal shelves fail to fuse typically during the sixth to eighth week of fetal development. The resultant opening, known as a cleft (Figure 13.3), occurs in about 1 of 700 live-born infants. Cleft lip and palate may occur alone or as part of a complex genetic syndrome, such as VCF syndrome. When a cleft lip or palate occurs in isolation, the risk that subsequent children will be born with cleft lip or palate is estimated to be 1%-3%.
In addition to the hypernasal speech that characterizes children with cleft lip and palate, problems with articulation can be expected if surgical correction is not performed. Another primary concern is difficulty with feeding. Surgical repair of the cleft lip is therefore performed around 2-3 months of age in most children, so that they may suck more effectively. A second surgery to repair the soft and hard palates is performed at around 1 year of age. Earlier repair of the palate can distort facial structure, and later repair would interfere more with articulation. Multiple surgical procedures may be required later in childhood to enhance jaw size, dental arch stability, tooth position, and bite (Kaufman, 1991). In addition, because middle-ear dysfunction frequently accompanies cleft lip and palate, affected children often require placement of pressure equalizing tubes to prevent frequent ear infections and the hearing problems that can accompany the infections.
Language Disorders and Their Causes
Until the mid-1970s, language disorders were thought to occur less frequently than speech disorders. However, several studies suggest this may not be the case. For example, the Beitchman et al. study (1986) found evidence for language disorders in about 8% of all 5-year-olds tested. Although language disorder may not have been the primary concern for all the diagnosed children, the study points out that language disorders may be more common than generally appreciated.
Unlike the disorders of speech, disorders of language generally are not classified according to the component of language that is affected. This is because children do not present with disorders that are restricted to only one component of language. Although Rapin and Allen (1988) have suggested a component-based classification scheme, their “lexical-syntactic” and “semantic-pragmatic” groupings can be difficult to describe and to recognize, and their classification is not in wide clinical use. Instead, childhood language disorders commonly are classified according to 1) whether the disorder is specific to language or is part of a more general cognitive disorder; and 2) whether comprehension, expression, or both are affected.
General Impairments Cause Language Impairments
Children who have mental retardation or global developmental delays almost always have language delays as well (see Chapter 16). Regardless of the etiology of their general impairments, it is extremely rare for a child’s language level to be more advanced than his or her general ability level. This fact and other evidence have led many psychologists to hypothesize that language development depends on certain underlying cognitive skills and cannot advance beyond the level of those skills. However, the identity of those skills has not been established with certainty. Children with pervasive developmental disorders (e.g., autism; see Chapter 21) also have language impairments as part of their primary diagnoses.
Expressive versus Receptive Language Disorders
Children whose language skills are significantly below their general cognitive abilities are said to have a specific language impairment (SLI). If their difficulties are primarily in the expression of thoughts and ideas, they are said to have an expressive language disorder. If they also have difficulties in understanding language, then they are said to have a mixed receptive-expressive language disorder. It is rare for children to have only a receptive language disorder (American Psychiatric Association, 1994).
For each of these disorders, the severity and particular language functions affected greatly vary. One child may have severe difficulties comprehending lengthy, grammatically complex sentences, while another may have no trouble in grammatical comprehension but have difficulty in finding the right word to express his or her thoughts. A third child might have particular difficulty in using prepositions that indicate spatial relationships (“through,” “beside,” “into”). Therefore, every child with a language disorder should have a thorough individualized evaluation.
Causes of Language Disorders
Just as childhood language disorders are heterogeneous in their manifestations, so too are the factors that underlie them. Because of the complexity of language and the neural mechanisms that underlie it, how these and other factors relate to each other is not yet known.
Language disorders may be subdivided into those that are acquired and those that are congenital (present from birth, which are far more frequent). For acquired language disorders, the etiology is often apparent from the child’s medical history. One common cause is TBI (see Chapter 27). Here, the etiology is clear, although exactly how brain processing has been disturbed is not. A rare cause of acquired language disorder is the Landau-Kleffner syndrome (LKS) (Paquier, Van Dongen, & Loonen, 1992). In LKS, language skills deteriorate after initially typical development. Children with LKS often have abnormal electroencephalograms (EEGs) (see Chapter 26) and also may have obvious seizures. It is hypothesized that the EEG abnormalities in LKS underlie the loss of the ability to process complex auditory signals such as speech. The resulting impairment of receptive language is accompanied by an impairment of expressive language. Children with LKS, as well as other children with language disorders, may be misdiagnosed as having autism. Children with autism, however, typically show other distinctive symptoms that should differentiate them from children with language impairments only. These include impairments in nonverbal communication as well as verbal communication, stereotyped and perseverative behaviors, unusually focused interests, and social skills impairments (see Chapter 21). Otitis media by itself is highly unlikely to cause significant language delays. Within a psychologically impoverished home environment, however, frequent ear infections are associated with language delays (Roberts, Burchinal, Medley, et al., 1995).
The etiology of congenital language disorders is less well understood. Some children with delayed language development have significant hearing impairments, but most do not. Whereas mild hearing loss is not a common cause of language impairment, impaired phonological processing may be a significant contributing factor. Tallal and colleagues (1996) suggest that the fundamental impairment for many children with SLI lies in their inability to process rapidly changing auditory stimuli despite normal hearing, an abnormality called a “temporal processing deficit” (Anderson, Brown, & Tallal, 1993). Human speech consists of just such complex, rapidly changing auditory stimuli. The fact that many children with SLI subsequently display reading disabilities may be related to these findings, because phonological processes are believed to be very important in the acquisition of reading skills (Catts, 1993; Scarborough, 1990). Tallal, Miller, Bedi, et al. (1996) have reported that these basic phonological impairments and the associated language impairments may be correctable with the use of carefully designed, computer-based remediation programs. This explicit identification of a fundamental processing impairment is much more helpful than the vague notion of a “central auditory processing deficit” that some children with SLI are said to have.
Magnetic resonance imaging studies of live subjects and pathological studies of autopsy brains have identified differences between the brains of people with and without SLI (Jernigan, Hesselink, Sowell, et al., 1991). These include abnormal patterns of left-right symmetry in language areas of the brain and the presence of neuronal heterotopias–cortical neurons in inappropriate places (see Chapter 14) (Galaburda, Sherman, Rosen, et al., 1984). A genetic contribution to the development of SLI is strongly supported by other studies. Bishop, North, and Donlan (1995) reported that identical (monozygotic) twins have close to 100% concordance for speech-language disorders. Familial studies have shown a much higher incidence of speech-language disorders in the parents of affected children than in parents of unaffected children (Tallal, Ross, & Curtiss, 1989; Tomblin, 1989). In one family, it has been suggested that there is a specific inherited inability to form the past tense of verbs (Gopnik & Crago, 1991). Further supportive evidence of a genetic influence comes from the study of children with reading disabilities. There is clear evidence for the familial transmission of reading disabilities, and geneticists have suggested that a specific locus on chromosome #6 is linked to reading disability (Cardon, Smith, Fulker, et al., 1994).
Some genetic syndromes that cause general cognitive impairment also show a characteristic pattern of language development. For example, individuals with Down syndrome often show greater impairment in their grammatical skills than in their vocabulary skills and general cognitive abilities (Fowler, 1990). In contrast, individuals with Williams syndrome typically show grammatical skills that are commensurate with their general cognitive skills. They sometimes show very specific impairments in grammar, however, such as the inappropriate over-regularization of verbs, for example, using “knowed” instead of “knew” (Bellugi, Wang, & Jernigan, 1994; Pinker, 1991). Continued study of syndromes such as these will further our knowledge of the genetic, neurological, and psychological bases of language impairments.
Who Should See a Speech-Language Therapist?
Early identification and treatment of children with communication impairments increases the likelihood that later disabling conditions will be minimized. Therefore, educators and therapists should always be alert to parental concerns about communicative development, and physicians should include screening of communication skills in their regular well-child visits. Children who are at high risk for impairment in communication skills, such as those who were born prematurely or who have hearing loss or other developmental delays, should be assessed at regular intervals for language function. Referral to a speech-language pathologist can then be made whenever a delay or impairment in communication skills is suspected.
Impairments and delays can occur in any one of the domains of speech and language or in combination. These impairments can occur either with or without associated physical disabilities, behavioral issues, or other medical problems. The trajectory of the child’s development should also be taken into account when considering a referral. Children who are progressing quickly after an initial period of delay are less worrisome than children who have plateaued or who are regressing (losing skills that they previously had). Table 13.1 lists some general guidelines for referring young children to a speech-language pathologist. Generally, children who are not producing 20 words by age 2 should be considered for evaluation. In older children, referral is warranted when parents or other caregivers are concerned about vocabulary or grammatical development, comprehension, changes in vocal quality or fluency, or any other disruption in the communication process.
Speech-language pathologists utilize an array of instruments and techniques in their evaluations. For the initial determination of the existence of a communication problem, parental reports and direct observations of the child in less-structured contexts are often most helpful. Information gleaned from these sources can be compared informally with the language and speech behaviors of children of similar ages. There are also systematic and norm-referenced methods for analyzing children’s spontaneous speech, whether it is observed by parents or by the speech-language specialist. The MacArthur Communicative Development Inventories (Fenson, Dale, Resnick, et al., 1993) is a parent questionnaire that assesses communication skills in infants and toddlers, which appears to correlate well with standardized clinician assessments.
Clinicians generally do not rely on a single standardized measure to determine the existence of a communication impairment (Smith & Damico, 1995). Instead, a combination of measures is used to probe many parameters of communicative competency. Examples of comprehensive measures of communication skills are the Preschool Language Scale (3rd edition) (PLS-3) (Zimmerman, Steiner, & Pond, 1992) and the Clinical Evaluation of Language Fundamentals (3rd edition) (Semel, Wiig, & Secord, 1995). These instruments include measures of the ability to 1) understand and use various grammatical forms, 2) follow spoken directions, and 3) formulate expressive language. When indicated, children with suspected language impairments also should undergo evaluation of their skills in articulation, concept acquisition, and pragmatic skills. Some of the more commonly used tests of speech and language skills are listed in Table 13.2. Most of these measures can be used to obtain both qualitative and quantitative descriptions of a child’s skills, including age-equivalent scores and standard scores.
The cultural diversity present in the United States requires speech-language pathologists to consider the linguistic background of the children being assessed. For children whose primary language is not English, interviewing the parents and administering norm-referenced tests can present considerable challenges. Few standardized measures for bilingual children are available, and most of these are for Spanish speakers. In some cases, the services of an interpreter may be required. Beyond linguistic differences, cultural differences in language pragmatics also must be considered. In some cases, the language assessment may provide only a gross estimate of the child’s skills. Such children probably are best served by a bilingual speech-language pathologist, when one is available.
Speech-language therapy services can be provided for preventive, remedial, or compensatory indications. Preventive therapies are administered for young children whose underlying medical conditions put them at high risk for speech-language impairments. Remedial therapies are designed to increase functioning in areas that already show impairment. Compensatory therapies allow children to adjust and use alternative strategies to bypass their communicative limitations. Remedial or compensatory therapy is indicated whenever there is a significant discrepancy between chronological age and communicative skill level or between general developmental skills and communicative skills.
Therapy may be administered individually, in a group setting, or in consultation with other professionals (e.g., teachers) and family members. The frequency of therapy may vary from daily to once every other week, depending on the type and severity of impairment. For example, a child with mild articulation impairments may receive direct therapy only once a week; while a child with language and communication skills that are significantly below general cognitive skills might receive direct therapy several times a week. It is important to keep in mind that communication is an interactive social process. Learning occurs naturally throughout the day, and optimal language learning will occur when families, teachers, and other caregivers are integrated into the therapy process on a daily basis.
Alternative Modes of Communication
Social interaction and purposeful communication are essential for children’s emotional health and development. Therefore, children who are unable to communicate through the auditory-verbal channel should be provided with an alternative mode of communication. The selection and development of the alternative communication system must take into account the child’s cognitive, sensory, and motor abilities, as well as the anticipated communicative partners.
Four types of alternative systems are commonly used: sign language, low-tech communication boards, high-tech computer systems, and the Picture Exchange Communication System (PECS) (Frost & Bondy, 1992). The first of these, sign language, refers to a collection of distinct methods for communicating with designated hand gestures (see Chapter 12). Sign language is an actual language; American sign language even has its own grammar and sentence structure. Obviously, children who use sign language must have communicative partners who can sign with them. When sign language is used for children without severe hearing impairments, parents often express concern that it will delay the development of spoken language. The available evidence, however, suggests that this is not true (Miller, 1992). Rather, sign language allows richer social interaction and decreases the children’s level of frustration, while spoken language continues to develop at the rate it would have.
Communication boards (Figure 13.4) vary in complexity from simple two-object picture boards to high-tech computer systems. Selection among these systems depends again on the children’s cognitive, visual, and motor abilities. The low-tech systems may include miniature objects, photographs, and Blissymbols (a picture/symbol code system). High-tech systems may include a keyboard; touch panel; or switch input and print, voice, or visual output. Prosthetic device modifications include headstick pointers and electronic scanning devices.
PECS requires an individual to give a picture of a desired item to a communicative partner in exchange for a desired item or activity. Children who use this system must have the cognitive ability to understand cause and effect and to associate pictures and symbols with meaning; and they must have the visual and motoric abilities to distinguish among pictures and to pick up and give the pictures to somebody, abilities that are generally present by a mental age of 18 months. Children with autism, who may communicate primarily to obtain desired outcomes, often benefit from this system.
Doug: A Boy with an Expressive Language Disorder
When Doug was 2-1/2 years old, his parents reported that he spoke very few words and no phrases or sentences. His medical history and other aspects of his development were typical, and he had normal hearing on audiometric testing. During his speech-language evaluation, Doug demonstrated good social and play skills. He scored at age level on the Peabody Picture Vocabulary Test-Revised (PPVT-R) (Dunn & Dunn, 1981), a test of receptive vocabulary, and on the Comprehension subtest of the PLS-3. However, Doug’s expressive language was limited to a five-word vocabulary that was intelligible only in context. He preferred grunting and pointing to make his desires known. His oral anatomy appeared normal, but Doug would not cooperate with oral-motor or speech-imitation assessments.
The diagnostic impression was that Doug had age-appropriate receptive language, but expressive language that was delayed at the 12- to 13-month level with a limited phonemic repertoire. It appeared that Doug had oral-motor planning difficulties or dyspraxia, which would require speech-language therapy. The modes of therapy were multifaceted. Doug was provided with individual speech therapy sessions twice weekly to facilitate mastery of new oral-motor postures and new and varied phonemes. Doug was encouraged by his early successes, and he quickly carried over his new sounds to a larger number of words. As his vocabulary expanded, therapy focused on sequencing of words into phrases and sentences, and the refinement of sequencing of sounds within words. It was recommended that elements of Doug’s therapy be incorporated into his home and school. To this end, Doug’s speech-language therapist consulted regularly with his parents and teachers, to provide additional practice and reinforcement for Doug’s newly learned skills.
At age 5, Doug’s vocabulary, sentence structure, discourse, and narrative skills are now acceptable for his chronological age. He continues, however, to exhibit mild articulation errors and unusual prosody. Nonetheless, he is doing well in kindergarten, and speech-language therapy has been discontinued for the present time. A follow-up evaluation will be performed in 6 months to assess future therapy needs.
The underlying etiology for a communication impairment is the single most important factor in determining the “shape” that a child’s language will later take. For example, in a child with cerebral palsy and severe oral-motor apraxia, a computerized communication board may permit good language expression. Dysphasia due to TBI tends to improve with recovery, but subtle impairments may persist (Ewing-Cobbs, Levin, Eisenberg, et al., 1987). For children with a communication disorder superimposed on a general cognitive impairment, language may improve greatly with therapy but should not be expected to surpass the general cognitive level. In children with autism, if expressive language has not developed by 6 years, it is unlikely to be functional in the future (Harris, Handelman, Gordon, et al., 1991).
For children with impairments in articulation, it is common to see resolution with appropriate therapy by the mid-elementary school years. Children with specific language impairments have a more variable prognosis (Bashir & Scavuzzo, 1992). Although the majority show substantial improvements, most retain subtle impairments in language and other aspects of learning that persist through adolescence and into adulthood (Aram & Hall, 1989). In particular, children with receptive language impairments are at a higher risk for reading disabilities than those with expressive impairments alone (Beitchman, Brownlie, Inglis, et al., 1994; Fenson, Dale, Reznick, et al., 1994). Because reading and language are so important for the acquisition of knowledge on other topics, many of these children show a global underachievement in later school years (Rissman, Curtiss, & Tallal, 1990).
Human communication is a complex phenomenon, with two primary facets: speech and language. Each is composed of multiple components. The neurological machinery that allows us to understand and produce language is correspondingly complex. It is a veritable miracle that so many children acquire language as easily as they do. When the process of language acquisition goes awry, it may be part of a general developmental impairment, or it may be an isolated problem. Regardless, children who have communicative impairments should have a comprehensive evaluation, including assessment of their general cognitive abilities, their hearing, and their many speech and language skills. An individualized therapy plan should then be constructed. With appropriate therapy and maturation, most speech and language skills are likely to improve, although there may be associated learning disabilities and residual impairments.
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