Some Characteristics of JSL Learners’ Productions of Long Vowels and Dependent Moraic Factors in Syllables

日本語らしい発音にはモーラという概念が重要であることはよく知られているが，多くの日本語学習者にとってモーラは認識が難しい単位である。そしてそのことは日本語学習者にとって特殊拍の習得の難しさにつながる。とりわけ長音を含む音節は2モーラ分の長さを持つが，モーラを十分に習得できていない日本語学習者は母音の持続時間を十分に確保することが難しい。本研究では長音を含む語の読み上げ実験を行い，日本語学習者と日本語母語話者の長母音産出の傾向について比較を試みる。また複数の学習者が長母音を短母音化して発音した語や，短母音を長母音化して発音する語については，特に取り上げて分析する。さらに，長音の誤用につながる可能性がある現象をいくつか指摘する。Mora is defined as a unit of temporal duration which is used to measure the length of words and utterances of Japanese. Acquiring mora makes Japanese learners easier to produce better utterances with natural rhythm in Japanese. On the other hand dependent phonological factors in syllables such as syllable closing nasals, first halves of geminate consonants, second halves of long vowels or diphthongal vowel sequences are counted as 1 mora and this is why acquiring Japanese mora is difficult for learners. In this research 13 Japanese learners’ voices that read 69 words were recorded to analyze characteristics of their production of the dependent moraic factors in syllables. We especially focused on long vowels, and some factors which may have influences on duration of long vowels were also discussed