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absence or impairment of speech in children caused by underdevelopment or lesions in the speech zones of the dominant hemisphere of the cerebral cortex.
There are two types of alalia: motor and sensory. In motor alalia, the motor functions of speech are impaired, while understanding of speech is basically retained. Alalic children will learn to pronounce individual sounds but not sound combinations and will often display syllable paraphasia, for instance, saying “kitchen” instead of “chicken.” As the alalic child acquires a vocabulary, he often develops agrammatism; he uses wrong case endings and does not use prepositions, conjunctions, or adverbs. In sensory alalia, the understanding of speech is impaired, while elementary hearing is retained. The alalic child makes an effort to speak, but his speech is completely unintelligible to others. Because of this profound speech impairment, alalic children become psychologically underdeveloped.
Instruction in reading and writing is difficult at all stages. Alalic children attend special schools where they are taught by special methods to pronounce words, construct sentences, and develop the ability of sound analysis of words, which helps in the formation of reading and writing skills. After training in such schools, children with motor alalia learn to speak and master the academic program of regular schools, although they proceed at a slower pace than normal children.