JOURNAL

OF COMMUNICATION

DISORDERS

11 (1978),

119-124

119

SPEECH DEVELOPMENT IN HEARING-IMPAIRED CHILDREN DANIEL School of Human Communication

LING

Disorders, McGill University, 1266 Pine Avenue West, Montreal, Quebec, H3G lA8, Canada

Many hearing-impaired children are unable to speak intelligibly. Research indicates, however, that patterns of errors typically found in the speech of such children could be largely avoided by systematic teaching. The purpose of this paper is to present and discuss a model for the progressive development of speech skills to the levels of automaticity required for fluent spoken language.

The history of teaching speech to hearing-impaired children spans several centuries. Over time, many strategies for improving intelligibility have been proposed. Some have been adopted and become part of the traditional repertoire of skills used by teachers of the deaf and speech pathologists alike. Others have been ignored or abandoned (often for no good reason) and many ineffective techniques have been adhered to despite their incompatibility with emerging knowledge. Accordingly, work in this area tends to be haphazard or stagnant rather than systematic and progressive. Results of treatment generally reflect this state of affairs. Indeed, relatively recent studies (Markides, 1970; Monsen, 1974; Nober, 1967; Smith, 1975) indicate that levels of intelligibility and patterns of speech error typical of children in schools for the deaf some 40 years ago are widely prevalent today. There are, of course, exceptions. These demonstrate that impoverished speech performance is not the inevitable outcome of profound hearing deficit. Indeed, if recent developments in speech science, phonetics, acoustics, sensory psychology, and education were integrated with those traditional techniques that have been proven valid, effective speech communication among hearing-impaired children would be the rule rather than the exception. This, in short, is the philosophy expressed in my recent book (Ling, 1976). In this article I shall present some of the thoughts and ideas that evolved over the years as I worked with hearing-impaired children and as I wrote the text. Central to my theme are the notions that the development of any given sound pattern demands the presence of previously acquired motor behaviors; that as new sound patterns emerge, they interact with those already established; and that failure to consider the sequence in which sound patterns are taught results in faults that hinder further development. Two types of order have to be considered: the first relates to the broad stages of speech acquisition and the second to speech target behaviors within each stage. The broad stages are depicted in Fig. 1. At the first stage, one requires abundant vocalization; at the second, voice patterns that D Elsevier North-Holland,

Inc.,

1978

0021.9924/78/0011-0119$01.25

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DANIEL LING

MAJOR STAGES OF SPEECH ACQUISITION PHONETIC

PHONOLOGIC

Fig. 1.

Sequential

stages in phonetic

LEVEL

LEVEL

and phonologic

level speech acquisition.

vary in intensity, duration, and pitch; at the third, specific vowel production; at the fourth, consonants; and at the fifth, consonant blends. At each stage, there are two levels of acquisition: the phonetic level, in which the main concern is to establish correct and clearly differentiated orosensory-motor patterns, and the phonologic level, in which established patterns are used meaningfully and systematically in communicative speech. There is relatively little overlap between the stages specified above. This is because, in essence, one cannot develop control over voice until vocalization is abundant; shape vowels accurately until adequate, independent control of the larynx and the articulators has been established; teach the child to produce the allophones of the various consonants unless the vowels with which they have to be coarticulated can be produced; or articulate consonant blends unless the consonant elements prerequisite for their development have been established. To define speech as consisting of only five major stages is, of course, a somewhat arbitrary procedure. Consonant acquisition may be considered as three stages rather than as one-the mastery of manner, place, and voicing distinctions. Consonant blend production may also be conveniently divided into three smaller parts, namely, word-initial, word-final, and medial or interlexical blends. What is important is not so much the number of stages specified, but recognition that orderly progress ensures the prerequisite behaviors that allow subsequent speech targets to be evoked and generalized without undue difficulty. Description of the speech targets within each stage, and of the rationale for teaching specific targets in a particular sequence, is outside the scope of this article. However, a few examples will illustrate some of the general principles involved. First, it is important to define the child’s task clearly and, so far as possible, foster error-free learning. Thus, the common confusion of high with

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loud and low with quiet-which arises because voice fundamental and vocal intensity both increase with subglottal pressure-can be avoided by sequentially establishing control of intensity and control of pitch. Second, the child’s sensory capacities must largely determine the strategies used to develop each speech target behavior. Strategies involving residual audition are generally the most effective and hence the order in which speech targets are selected must accord with the systematic development of the child’s listening skills. Thus, teaching manner distinctions among front consonants should precede the development of place and voicing distinctions. Manner distinctions among front consonants are relatively easy to perceive and produce, even for the child with extremely limited residual hearing. When they are taught, not in isolation but as a means of interrupting an established vocal stream, they are characterized by variant low-frequency acoustic energy. They are also the consonants most readily seen and, because there is greater tactile sensitivity toward the front of the mouth, they likewise yield the clearest orosensory-motor patterns. Most place distinctions call for relatively good highfrequency hearing and hence may be inaudible to the more severely hearingimpaired child. Voicing distinctions are signaled as much by fine durational cues as by vocal cord vibration and their mastery cannot be expected of a child in the earliest stages of consonant acquisition. Third, the motor skills involved in producing speech targets must be increasingly refined within a given stage. Thus, word-initial consonant blends involving the sequential production of sounds formed with two organs-the tongue and the lips-as in [sp] should be taught before those involving the coarticulation of adjacent sounds produced principally with one organ-the tongue-as in Fl]. When the teaching of speech targets is orderly and progressive, i.e., when the prerequisite behaviors for their production have been systematically developed, then it becomes relatively easy to evoke the new behaviors desired. Indeed, to evoke a new segmental speech target behavior should usually be less than a minute’s work. But to evoke a sound pattern is not enough. The child must generalize its production to various phonetic contexts, practise it toward automaticity, and then assimilate it into his phonology. In short, each speech target behavior may be considered as consisting of a series of component subskills, each of which the child, hearing-impaired or normally hearing, must master before he can use it in his communicative speech. The component subskills which underlie each sound pattern increase in complexity as the child moves from one stage of acquisition to the next. Thus, the subskills that underlie undifferentiated vocalization are simpler than those that underlie voice control, and those that underlie consonant blends are more difficult than those underlying targets at any other stage. Consonant targets which have the same manner of production have most subskills in common, but subskills for most segmental targets share some characteristics. This is because each

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segmental target must, once it has been evoked, be repeated, generalized to a variety of phonetic contexts, and alternated with other segmental patterns. Repetition and alternation in various phonetic contexts at rates required for normal speech (at least three syllables/second) demand levels of automaticity that can be achieved only through overlearning-training beyond 100% accuracy to reduce the latency of, and conscious attention to, each subskill. One advantage in providing a detailed description of the numerous subskills that underlie each speech target behavior is that it provides the teacher, therapist, or parent with a series of unambiguous goals. Another advantage is that the child’s progress toward each goal can be incrementally tested at both phonetic and phonologic levels as he is being trained. Discrepancies between results for phonetic and phonologic testing may thus be used to indicate how criterionreferenced training should be modified to ensure optimal progress. Tracking the rate at which each subskill is acquired by each child also permits one to determine the efficiency of various possible teaching strategies (see Ling and Bennett, 1974-75). Such tracking also allows one to ascertain whether a child is, indeed, a candidate for continued oial instruction, for if ongoing evaluation reveals that no known strategy leads to the acquisition of new speech subskills, then altematives, e.g., the adoption of sign language as the child’s major means of instruction and communication, should be explored. A child’s failure to acquire spoken language may, of course, be due to intrinsic factors, such as additional neurological impairment, or extrinsic factors, such as poor quality teaching, segregation from normally speaking peers, or inadequate parental participation. More often than not, the major barriers to a hearingimpaired child’s acquisition of speech are socio-educational rather than personal. The professional responsible for teaching the child to talk must, therefore, be prepared to work outside actual speech training sessions to ensure that adults and peers communicate with the child through speech. One cannot expect a child to develop spoken language if his environment is not conducive to verbal interchange and development. There are many traditional notions on teaching speech to hearing-impaired children that must be challenged. One is that orthographic or other phonemic symbolization systems are essential to the acquisition process. They may, in fact, impede progress. Another is that some form of feedback involving moment-bymoment control of articulation is essential. This is not so. Too many current teaching strategies involve training the child to attend to feedback, while too few focus on feedforward-the correct planning and serial ordering of speech sequences that permit fluent coarticulation. Yet another questionable notion is that vision is an aid in all aspects of speech reception and in teaching speech production. There is evidence to the contrary. Indeed, many of the devices and strategies developed as visual aids should be carefully scrutinized and their general applicability rejected. Then there is the notion that speech patterns should

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be taught in isolation or, at the other extreme, taught and corrected only in meaningful words or longer linguistic units. There is, again, evidence to contradict advocates of either point of view. First, speech patterns are not just articulated but coarticulated, and there is no way that plosives or stops (which are really two different manners of production) can be taught in isolation or developed to automaticity in isolated syllables. Similarly, velar function for nasal consonants and vocal cord function for voiced consonants cannot be effectively taught except in contexts spanning several articulatory events. Second, if a child has difficulty in producing a sound pattern, then teaching or correcting it in meaningful units such as words or phrases invites him to form associations between the semantic properties of the word or phrase and the difficulty of its production. My concluding remarks reiterate the professional’s responsibilities for obtaining generally higher standards of speech, and the hearing-impaired child’s abilities to achieve them. In contrast to what has been generally achieved to date with what is currently known, it becomes evident that many of the faults typically present in the speech of hearing-impaired children are there because, in ignorance of the dynamics of speech, professionals regularly teach children to produce speech patterns wrongly. Prolongation, nasalization, neutralization, and intrusive voicing-typical faults-are the direct result of poor teaching. Similarly, the typical omission of certain patterns is due to the professional’s failure to ensure that the child develops the range of behaviors prerequisite for their production and achieves mastery of the subskills that underlie them. In short, the general prevalence of poor speech is due to failure of the professional rather than to incapacity of the child. Speech communication among hearing-impaired children will remain poor if professionals continue to view speech as a subject to be taught-an item in the parent-infant program or a topic in the special school’s curriculum-rather than as the medium through which the child should receive most of his education and develop socially at home and at school. Early and effective spoken language development geared to the receptive and expressive needs of the individual child has not been given adequate priority; hence, generations of children have been labeled as “oral” not because they can talk, but because they do not use signs. With the guidelines for effective work clearly defined (see Ling, 1976), there is every hope that professionals will be able to ensure that future generations of hearing-impaired children will more nearly realize their potential for spoken language. This article’represents the dry bones of an invited lecture given at the Seventh Conference in the Mount Sinai Series in Communication Disorders under the Chairmanship of Dr. Asher Bar. The views expressed are supported by the writer’s recent text entitled Speech and the Hearing Impaired Child: Theory and

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Practice, published Washington, D.C.,

DANIEL LING

by the Alexander 1976.

Graham

Bell Association

for the Deaf,

References Ling, D. Speech and the hearing-impaired child: theory andpractice. Washington, D.C.: Alexander Graham Bell Association for the Deaf, 1976. Ling, D., Bennett, C. W. Training severely hearing-impaired children in vowel imitation. Hum. Commun., 19741975, 3, 518. Markides, A. The speech of deaf and partially-hearing children with special reference to factors affecting intelligibility. Br. J. Dis. Commun., 1970, 5, 126140. Monsen, R. B. Durational aspects of vowel production in the speech of deaf children. J. Speech Hear. Res., 1974, 17, 386398. Nober, E. H. Articulation of the deaf. Except. Child., 1967, 33, 61 l-621. Smith, C. R. Residual hearing and speech production in deaf children. J. Speech Hear. Res., 18. 795811.

1975,

Speech development in hearing-impaired children.

JOURNAL OF COMMUNICATION DISORDERS 11 (1978), 119-124 119 SPEECH DEVELOPMENT IN HEARING-IMPAIRED CHILDREN DANIEL School of Human Communication...
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