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Speech sound disorders are speech disorders in which some speech sounds (called phonemes) in a child's (or, sometimes, an adult's) native language are either not produced, not produced correctly, or are not used correctly. == General characteristics == Errors produced by children with speech sound disorders are typically classified into four categories: *Omissions: Certain sounds are not produced — entire syllables or classes of sounds may be deleted; e.g., fi' for fish or 'at for cat. *Additions (or Commissions): an extra sound or sounds are added to the intended word. *Distortions: Sounds are changed slightly so that the intended sound may be recognized but sounds "wrong," or may not sound like any sound in the language. The best known example of a distortion is the lisp. *Substitutions: One or more sounds are substituted for another; e.g., wabbit for rabbit or tow for cow When systematically done, depending on the phoneme exchanged it is called: * Iotacism/Itacism * Lambdacism * Rhotacism * Sigmatism In some cases, these terms are used for general patterns in the evolution of a whole language. Sometimes, even for experts, telling exactly which type has been made is not obvious — some distorted forms of /r/ may be mistaken for /w/ by a casual observer, yet may not actually be either sound but somewhere in between. Further, children with severe speech sound disorders may be difficult to understand, making it hard to tell what word was actually intended and thus what is actually wrong with it. There are three different levels of classification when determining the magnitude and type of an error that is produced: # Sounds the patient can produce ##A: Phonemic- can be produced easily; used meaningfully and contrastively ##B: Phonetic- produced only upon request; not used consistently, meaningfully, or contrastively; not used in connected speech # Stimulable sounds ##A: Easily stimulable ##B: Stimulable after demonstration and probing (i.e. with a tongue depressor) # Cannot produce the sound ##A: Cannot be produced voluntarily ##B: No production ever observed Note that omissions do not mean the sound cannot be produced, and some sounds may be produced more easily or frequently when appearing with certain other sounds: someone might be able to say "s" and "t" separately, but not "st," or may be able to produce a sound at the beginning of a word but not at the end. The magnitude of the problem will often vary between different sounds from the same speaker. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「speech sound disorder」の詳細全文を読む スポンサード リンク
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