9.10 Zones of speech-language development.

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Systems of some complexity are easier to understand when represented by a model that shows the successive steps in the development of that system. Such a model is the spherical representation used throughout this book: a hard core in the centre surrounded by self-generated hulls of ever greater plasticity. Speech and language development can be represented by a concentric growth model (analogous to the one we have described for the central nervous system). This model is an elaboration of the Piagetian notion of cognitive development in steps. A model of concentric growth is supported by the observation that the perceptual and expressive skills of hearing and speech are acquired in stages: in the Map they are called Levels. The modes of communication between mother and child develop, moving from vocal - non-verbal - signs and signals, to verbally transmitted complex messages. Later the complete grammar and syntax of the spoken language are mastered by the child.

From the full blown sphere of the VAD system we have again punched out a part which on a flat surface becomes a sector of a circle. When this sector stands on its mid-point it resembles a cone standing on its point. This point is the centre from which communication is activated. The hulls or layers that surround it have been generated by the centre. They execute the emotional need to relate by successively creating ever more finely differentiated instruments for its fulfilment: first non-verbal skills (nrs 1-3 in Map 9.10.1) and later the verbal skills (nrs 4-6). The idea that language, analogous to the lymphoid and the neural system serves the defence and adaptation of man, has already been referred to in the beginning of this Chapter (9.4)

Map 9.10.1 summing up six layers or subsystems in oral communication:

(1) Activation

Most important is the activating system. Closest to the physiologic regulatory functions, it breeds attention and motivation, and these two are fundamental to learning. A certain degree of alertness is needed for learning. When the level of attention is low, new knowledge or skills fail to develop. Over-activation is equally undesirable: excitement or anxiety prevent the mind from concentrating on new tasks and can even lead to regression (6.5). A mentally healthy infant can summon the attentiveness, necessary for discovering and mastering the hidden codes of speech and language. The influence of emotional conditions during the critical period of speech-language development is widely underestimated.

(2) Voice and intonation.

The mother's voice is the first meaningful auditory stimulus which infants perceive and to which they learn to respond. It is likely that the voice of the mother has already made an impression on the child while it is still in the womb. After birth, smell, touch and sound-play serve an early emotional bonding between mother and child. The melody of a voice expresses moods and emotions. The meaning of this 'song without words' is coded in the tonal pattern: rising with increased activation, descending when it comes to rest. Recognizing tonal patterns is a preamble to non-verbal communication. It requires auditory discrimination of intonation patterns, the meaning of which can vary, from reassurance to warning, alarm or even agony. Gradations of vocal qualities and intonation remain important cues for speech communication throughout life. They signify the speaker's state of mind and his intentions. When laughing, singing, crying, sighing, moaning, scolding, the tone and rhythm weigh more than the content of the words.

For a baby the acoustical environment of a baby consists mainly of people talking, laughing or shouting. A baby's early interpretations of meaning is probably based on these prominent qualities of the voice: loudness and intonation. Intonation patterns of adult speech are among the first successful imitations of bedtime monologues.

Babies and infants are utterly dependent on their environment for obtaining food and care. For this reason they are genetically so programmed that from birth on they exert influence on and interact with their nursing parent, to signal needs and to obtain fulfilment. Successful trials will enhance the baby's motivational competence. He retains sound patterns and associates them with meanings. Later he scans the environment for meaningful sounds and responds to them with his own vocal gestures.

(3) Rhythmic sound sequences. Discrimination and control of temporal features of the sounds produced: rate of repetition, duration, rhythmic sequencing. There is reason to presume that already before birth these features are perceived. They are closely related to the movements which the unborn child has experienced when its mother was walking, dancing, trotting and rocking. Several authors have indicated that there is a connection between the functioning of the labyrinth and speech-language development. When the perception of movement and head-position was impaired, spatial orientation and speech-language development were delayed.

Varying vocal inflection and rhythmic patterns can as such evoke a world of moods and states of mind: singing, shouting, laughing and crying are non-verbal modes of communicating. Their importance cannot be overestimated. As long as an infant is without speech it depends for its contact with the environment on non-verbal auditory impressions and on such visible means as body posture and movement, and facial expression.

It is understandable that nursery-rhymes have been vehicles for speech- and language acquisition since times immemorial. Rhythm allots time-slots to be filled with meaningful syllables, rhyme reinforces the recognition of phonologic features. Moreover, saying nursery-rhymes out loud is excellent training for a controlled rate of speech. As we will see later, hastiness and avoiding of pauses can signify insecurity and fear.

(4) Articulation: discriminating the combined features of articulated sounds and training the neuromotor control of their production. When a young child "speaks its first word" it is certainly a memorable moment for its parents.. The term 'articulation' is generally used for the production of speech sounds. Of equal importance however is the capacity for sound discrimination that has preceded it. This is the receptive side of articulation: the auditory discrimination of characteristic features of speech sounds. It requires not only intact hearing, but also a 'listening attitude'. Recognizing speech sounds is the first step. It is soon followed by attempts to imitate them. The distinctive features of speech-sounds (phonemes) are not learned in isolation but in forever changing connections in words and phrases. The perceptual skill of feature-discrimination has its roots in the earlier organisation of tonal and temporal patterns and in the ability to inhibit background noise in favour of relevant signals (figure-ground contrast function). Sound environments are not the same for all children: much depends on the type of household and the living circumstances. A noisy daytime-nursery is the worst possible environment, with noise-levels amounting to 90 dB, driving the children as well as the nurses to mental exhaustion, and allowing only the most stony species of both to survive.

Retaining and reproducing a one-word sentence is a modest achievement. The next step, to the two-word sentence, is a large one. It brings us to level (5).

(5) Language. This is the level of semantic abstraction, the form and structure of language: grammar and syntax. Within the rules of syntax there are infinite possibilities for meaningful phrases. Grammatical rules allow a variation of word-forms for different functions. Most children of four have a large vocabulary at their disposal and produce grammatically and syntactically correct phrases with ease. Several children who were slow in developing connected speech may later show symptoms of cluttering.

The amount of information that has to be processed on the way from hearing to understanding is staggering. However the language decoding system has found ways to economise the process. Only relevant cues are picked up and at least 50 % of the information is neglected. Deciding what is relevant and what can be dropped is, of course, a very clever development. Furthermore, recognising sequences of function words and content words is not done in small pieces but in chunks which consider the whole of the spoken sentence. A "reverberating" auditory memory holds the phrase available for scanning analysis and a sort of "working memory" (short term memory) holds all possible relevant meanings and structures in readiness.

When for the fifth level the time has come to be actualised and to start functioning, it has already well developed functions to stand on : (1) the prosodic elements giving an indication of the emotional contents and leaving cues about what part of the phrase has priority for attention, (2) recognition of contours and patterns of sounds that frequently occur in known situations.

Children that suffer from a severe mental handicap will not succeed in acquiring verbal competence beyond, perhaps, the one word phrase. Still they are able to understand and use a simple sort of language. Between such borderline language communication and the full use of language with all its subtleties there is an enormous difference.

(6) Logic and rhetoric: the combination of logical thinking, imagination and social skills that form the crown on the art of oral communication.

Even when speech-language functions have developed well at the levels 1 - 5, there remains one additional level to be mastered. It is the skill to give the spoken message its optimal form; shaping the message in a way that holds the listeners attention and makes it easy for him to grasp the contents. A good speaker senses the feelings and expectations on the part of the listener (that is the receptive side of rhetoric skill) and phrases his message into well chosen words, that by the intonation and the suitable rate of speaking make the message resound in the listener's ear (the expressive side). At this level one speaks well prepared with a sound knowledge of the subject matter and persuasive arguments. This can eventually be learned under guidance and with much practice. Many clutterers even with reasonable articulation and language abilities fail as communicators; they have been notably unable to develop their speech skills at this level.

Note that at the levels 2 - 5 we have to distinguish the receiving (hearing, listening, reading) aspect from the productive or expressive (voice, articulation, writing) aspect. In the receiving mode there is temporal integration over increasingly longer samples, in the productive mode the levels show increasingly longer response times. The concentric layered structure is such that from the centre outward stimuli of longer duration are integrated.

Map 9.10.2 The subsystems of speech communication in key-words:

The higher ranking levels surround the lower ranking levels like extension zones of a city; there is interaction between all levels. Levels 1-3 apply to vocal but non-verbal modes of communicating, levels 4-6 to verbal communication only. Note that the response times of the levels 4-6 increase progressively: the time phonemes take is in the order of tens of milliseconds, words hundreds, phrases take seconds to be processed (GJ Dalenoort in a review of a book The symbolic species, by TW Deacon, 1997).

9.11 Underdeveloped zones: empty lots and ramshackle houses.