同卵雙胞胎語言發展遲緩之個案研究

Abstract

本論文旨在描述臨床上一對六歲同卵雙胞胎姊妹的語言障礙。此對雙胞胎之母語為國語，語言特色在於她們彼此說話溝通似乎無太大問題，但她們與其他人溝通卻有問題：她們說的話經常無法讓人聽懂，而她們也偶爾聽不懂別人的言語。隨著年齡的增加，說話清晰度卻是與同鈴兒童的差距愈來愈大，似有發展遲緩的現象。初步診斷為聽力正常、發音器官正常、智力中等，無神經系統異常的跡象。\r\n 本研究除了對此對雙胞胎─p與H的音韻障礙作共時性(Synchronic)的描述外，亦做歷時性(diachronic)的描述，並且比較P與H之間的音韻發展。研究期間自她們五歲十一個月至六歲兩個月。音韻發展分為三階段：第一階段5；11，第二階段6；0，第三階段6；2。\r\n 研究結果顯示，在第一階段p與H有相同的音韻障礙：音節節尾鼻音省略(Syllable-final nasal deletion)、複元音弱化(diphthong reduction)、三元音弱化(triphthong reduction)、替代音[I]substitution)、與顎化(palataliztion)。P與H有相同的音韻系統。但由於障礙出現的頻率，H較P高，因此P的說話清晰度較H為高。此外，P有上聲變調的問題。在第二階段，P與H有不同的發展。P發展出音節首鼻音/n/及韻母/î/，H則大致停留在第一階段的程度，但出現上聲變調的問題。至第三階段，P發展出聲母/z/、韻母/ai/與/uai/，語音顎化幾乎消失，上聲變調規則穩定；H則發展出音節首鼻音/n/，同時，上聲變調規則亦趨於穩定。\r\n 由以上的發展記錄可以得到下列結論：一、兒童語言發展過程中，規則的習得往往是模糊不清的，一條規則不見得皆用於語境相同的字詞上，即使在同一字詞上，規則時有時無。二、本個案與國外（美國、歐洲、澳洲）研究所得之結論相符，即：同卵雙胞胎為語言發展異常的高危儉群，尤其是音韻障礙。三、P與H有明顯音節結構簡化的現象，朝CV的結構發展。四、儘管P與H為同卵雙胞胎，語言發展速度並不相同。不過發展的步驟卻十分類似。H於第二階段的程度正好是P第一階段的程度：H於第三階段的發展接近P第二階段的發展。五、在學齡前適時的介入，患者依然有語言恢復正常的可能。

This study intends to describe the linguistic disorders of a pair of Mandarin-speaking monozygotic twin girls at the age of six. One of the main characteristics of their speech is that they can communicate with each other but they have communication problems with other members of the family and the society. It seems that when they are getting older and older, their speech intelligibility does not increase with age. The twin sisters are, thus, suspected to be developmentally delayed. The preliminary diagnosis indicates that the pair of twins, P and H, have some articulation disorders, but with normal hearing, normal articulatory organs, and normal intelligence. Also, no symptom or syndrome indicates any neurological disorder.\r\n The study is aimed to describe the phonological disorders of P and H synchronically and diachronically, with comparison between P and H at each developmental stage. The phonological development is composed of three stages: Stage I when they are 5;11, Stage II when 6;0, and Stage III when 6;2.\r\n The results indicate that P and H share the same types of disorders at Stage I: 1) syllable-final nasal deletion, 2) diphthong reduction, 3) triphthong reduction, 4) [I] substitution, and 5) palatalization. And, they share the same phonological system. Because of the higher frequency of these processes in H than in P, the speech intelligibility is better in P than in H. In addition, P`s third tone sandhi rule is problematic. At Stage II, their development is different. While P has developed the syllable initial / n / and the final /î/, H hardly makes progress. Besides, H`s third tone sandhi rule becomes problematic. At Stage III P has developed the initial /z/, the finals / ai / and / uai /, and the palatalization process almost disappears. H has developed the syllable initial /n/. The third tone sandhi rule becomes stable both in P and H.\r\n Five conclusions can be drawn from the case study. First, in the process of child language acquisition, the rules a child learns are largely opaque rules. Second, the results of the case study are compatible with previous research in America, Europe and Australia on twins` language development: twins are a high risk group vulnerable for developmental dysphasia, especially for phonological disorders. This case study offers a piece of evidence for previous observation on twin children speaking other languages. Third, the speech tendency of P and H is to simplify the syllable structure towards the \"CVCV\" form, leaving the so-called \"open syllable\". Fourth, although P and H are a pair of monozygotic twins, who are usually supposed to have many physical as well as psychological characteristics in common, their language development is different. However, it is interesting to note that H`s level at Stage II is almost the same as P`s level at Stage I, and H`s level at Stage III is the same as P`s level at Stage II. Finally, the study shows that if appropriate intervention and therapy is carried out during the preschool years, there is still a possibility for them for coming back to the normal state.