北方言語研究 = Northern Language Studies;第11号

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The Merger between /ʊ/ and /o/ in Khalkha Mongolian : A Study Based on an Acoustic Analysis and a Perceptual Experimen

UETA, Naoki

Permalink : http://hdl.handle.net/2115/80939
KEYWORDS : Khalkha Mongolian;vowel contrast;merger;acoustic analysis;perception

Abstract

Mongolian has seven basic vowels /i, e, a, u, ʊ, o, ɔ/. Although /ʊ/ and /o/ are considered phonemically contrastive in this vowel system, the phonetic realization of these two vowels is not necessarily clear since their phonetic descriptions differ across previous studies. Further, some studies claim that both /ʊ/ and /o/ can be pronounced as [o]. Thus, there is room for discussion about whether the phonetic characteristics of these vowels are sufficiently different to distinguish each other, and whether they are actually differentiated perceptually by native speakers. This study addresses the merger between /ʊ/ and /o/ in Mongolian from the perspectives of acoustic characteristic and perception. An acoustic analysis confirmed that the F2 values of long /oo/ were constantly higher than those of /ʊʊ/, while the F2 values of short /o/ were close to those of /ʊ/; both are unstable. This suggests that the acoustic characteristics of Mongolian /ʊ/ and /o/ are not sufficiently different to completely distinguish these vowel phonemes. A perceptual experiment on distinguishing between /ʊ/ and /o/ revealed that /ʊ/ was perceived as /ʊ/ at a rate of nearly 90% while /o/ was not distinguished from /ʊ/ in approximately half of the stimulus sounds. This means that Mongolian /o/ has perceptually merged into /ʊ/. In addition, the merger of /o/ into /ʊ/ has occurred for both the short and long vowels to a similar extent. This result runs parallel to the claim in Ueta (2019), which pointed out that /ʊ/ and /o/ have been merging regardless of the vowel length in some speakers. The results of this study lend further support from the perspective of perception.

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