臺灣人日語學習者之二重母音時間特性——以長音為對照之聲學分析

Temporal Characteristics of Japanese Diphthongs in Taiwanese Learners of Japanese: An Acoustic Analysis in Comparison with Long Vowels

本研究以43名臺灣人日語學習者及4名日語母語話者為對象，從聲學分析的角度探討日語二重母音的時間特性。研究同時比較不同學習階段之間的差異，並透過與長音的對照考察其特徵。分析以普通拍語的母音持續時間（V1）為基準，採用二重母音持續時間比（V1J／V1）與長音持續時間比（V1R／V1）作為指標。分析結果顯示，臺灣人日語學習者的V1J／V1顯著低於日語母語話者，且隨學習階段提升而呈增加趨勢。此結果顯示，學習者對二重母音時長的控制可能呈現階段性發展。此外，V1J／V1與V1R／V1之間呈正相關，顯示學習者對二重母音與長音時長的控制能力之間具有一定關聯。然而，延長差（△）與比率（Ratio）的分析亦指出，學習者雖已在一定程度上掌握母音延長這一基本時長控制方式，若以V1為基準來看，二重母音與長音的相對時長配置，仍未完全達到母語者水準。

This study investigates the temporal characteristics of Japanese diphthongs produced by 43 Taiwanese learners of Japanese and 4 native Japanese speakers from an acoustic perspective. It compares differences across learning stages and examines diphthongal timing through comparison with long vowels. The analysis used the diphthong duration ratio (V1J/ V1) and the long-vowel duration ratio (V1R/ V1), with the vowel duration of monomoraic words (V1) as the baseline. The results showed that learners' V1J/ V1 values were significantly lower than those of native speakers and increased with learning stage, suggesting that the control of diphthong duration may develop in stages. A positive correlation was also found between V1J/V1 and V1R/V1, indicating a relationship between learners' control of diphthong and long-vowel duration. However, analyses of the extension difference (Δ) and ratio (Ratio) revealed that, although learners had acquired the basic durational pattern of vowel lengthening to some extent, their relative durational patterning of diphthongs and long vowels, with V1 as the baseline, did not fully match that of native speakers.