精神的緊張が発話速度に与える影響—精神的緊張と速度感に与える因子の検討

The effects of mental tension on speech rate: Examination of factors affecting mental tension and sense of speech rate

　精神的緊張による発話速度の上昇は，dysarthriaの臨床において発話明瞭度向上の阻害因子となり得るものであり，その速度感の認知に影響を及ぼす要因を明らかにすることは，dysarthria例へのアプローチに応用できると考えた．そこで，精神的緊張により発話スピードが速くなる際の話し手の速度感に影響する要因について，2条件のもと，その変化を測定・検討した．健常者22名を対象に，「音読の評価」を心的負荷として心的負荷条件とコントロール条件で音読を実施した．その結果，心的負荷条件で精神的緊張と速度感はともに高くなり，発話速度と調音速度の上昇，全時間の短縮，休止数の減少，基本周波数の上昇を認めた．その際，精神的緊張と発話速度・全時間とは強い相関を認めた一方で，速度感と有意な相関を認めた指標はなかった．これらのことより精神的緊張による速度感の認知は，発話として表出される指標以外の指標との関連が示唆された．

　Increases in speech rate caused by mental tension can inhibit the improvement of speech intelligibility in dysarthria treatment. Thus, understanding factors that influence speakers' sense of their speech rate can have implications for the treatment of dysarthria. This study attempted to examine the factors affecting speakers' perception of their speech rate under 2 conditions. Twenty-two healthy participants were asked to read aloud under the mental strain condition and the control condition. Their reading performance was then analyzed. The results indicated that both mental tension and participants' sense of speech rate increased under the mental strain condition. This was revealed by increases in the rates of speech and articulation, reductions in the overall speaking time and the number of pauses, and an increase in the fundamental frequency of speech. Although strong correlations were found between mental tension and the speech rate and total speaking time, no indicator showed a significant correlation with participants' sense of speech rate. These results suggest that the perception of speech rate under mental tension may be related to indicators other than those expressed as speech.