舌小帯短縮によるラ行構音障害の実験的研究—ソナグラフによる分析

　舌小帯短縮によるラ行構音障害に於いて，その発音が正常とは如何なる差異を示すかと言う点に関しては子音の分析が困難であるため未だ明らかではない様である。今回この点に関して一つの実験を試みたのでその結果を述べる。

The study consisted of sonagraphic analysis of pronoucing the ra-line of Japanese kataka-na, "ra ri ru re ro" under two different con-ditions, namely normaly at first and then in such a way by fixing the tip of the tongue at the root of the lower incisors firmly wi-thout movement. The records of these two types of dilivery were compared to each other.

Under normal conditions the pronounciation of Japanese "r" contains two bars whose mean frequencies are approximately 0.5 and 1. 5kc respectively, the beginning of the vib-ration being sharply defined. Under the fixed condition there was a diminishing effect on the 1.5kc bar and the 0.5kc bar was not sharply defined in its beginning but under went a change of a slow build-up.