健常者20名に文章を音読させ, 音読速度と, 音読速度調節の際に用いる方略を調べた。音読は, 通常, ゆっくり, できるだけ速くの3種の速度で行うよう指示した。健常者の平均音読速度は通常の速度で, 360.6モーラ/分, 335.0音節/分, 89.8文節/分であった。ゆっくりと音読した場合には, 通常速度の場合より, 文全体に占める発話時間の割合が減少し, 休止時間の割合が増加した。できるだけ速く音読した場合には, 通常速度の場合より, 文全体に占める発話時間の割合が増加し, 休止時間の割合が減少した。発話時間, 休止時間の各々をみると, ゆっくりと音読した場合にも, できるだけ速く音読した場合にも, 発話時間に比べ, 休止時間の変化率が高かった。健常者は, 構音運動自体よりも休止時間の増減により, 発話速度の調節を行っていることが示唆された。

The purpose of this study is to investigate oral reading rates and rate control strategies in normal speakers. In experiment 1,the subjects were instructed to read a story "Kitakaze to taiyo", commonly used in clinical examination in Japan, under three conditions : for the first and second trials in the habitual rate of each subject, for the third in one's slow rate, and for the fourth in one's fastest rate. The overall reading rates were represented as the number of morae, syllables, and sentence segments (bunsetsu in Japanese) per minute. The mean habitual reading rate was 360.6 morae/min., 335.0 syllables/min., 89.8 bunsetsu/min. In experiment 2,One sentence, extracted from the same materials as experiment 1,was segmented to two domains : speaking and pause periods to examine rate control strategies. In the slow reading mode, while the speaking duration time was decreased, the pause duration time was increased. In the rapid mode, while the speaking duration time was increased, the pause duration time was decreased. Concerning the changes of the speaking duration time and the pause duration time respectively, the pause duration time was markedly changed compared to the speaking duration time in both slow and rapid mode. The results suggested the speech rate control adopted more flexible temporal adjustment during the pause period than the articulately movement itself in normal Japanese speakers.

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