口蓋化構音の構音動態と音響的特徴の関連―症例間の差異の検討―

抄録

歯茎破裂音/t, d/が口蓋化構音となった際の構音動態と音響的特徴を, 症例間の差異という観点から調べ, 両者の関連を検討した.硬口蓋と舌の接触様式をダイナミックパラトグラフで観察すると, 最大接触時に舌が, 1) 硬口蓋全体に広く接触する型と, 2) 硬口蓋後縁あるいは硬口蓋中央部までの接触にとどまる型に分類された.破裂音の構音点は症例間で異なり, 硬口蓋前中部から軟口蓋までのいずれかの部位と推定された.サウンドスペクトログラフを用いて, (1) バースト部のインテンシティー・スペクトラム上, 最大値を示す周波数 (ピーク周波数) , (2) フォルマント遷移, (3) Voice Onset Time (VOT) を分析すると, 症例間で音響的性質は一様ではなく, ピーク周波数および後続母音が/e/の音節の第2フォルマント遷移については, 構音点が歯茎寄りの症例と軟口蓋に近い症例で音響的傾向が異なる可能性が示唆された
【英文要旨】.
Diversity of articulatory tongue movements and acoustic characteristics of palatalized articulation were analyzed in producing the plosives/t, d/. The subjects were 10 postoperative cleft palate patients, ranging from 5 to 8 years old. Two patterns of tongue-palate contact were confirmed in the maximum contact: 1) contact of the tongue blade over the whole part of the hard palate, 2) contact of the back of the tongue to the posterior end or to the middle of the hard palate. It was observed that distorted sounds were produced due to erroneous contact of the tongue at various points, ranging from the anterior part of the hard palate to the soft palate. Among the acoustic features of the plosives produced by the subjects, the peak energy frequency of the burst and the second formant transition when the plosive is followed by [e] were different, corresponding to the articulatory points. The voice onset time was not consistent with the corresponding articulatory points, however.