Incomplete Vowel Lengthening in Japanese: A First Study

Many phonetic studies have investigated cases of incomplete neutralization, where contrasts that are seemingly neutralized phonologically nevertheless leave some phonetic distinctions. The majority of this previous work, however, focuses on the case of final devoicing in different languages. Building on this body of the literature (see Braver 2013 for an overview), this paper offers a new case study of incomplete neutralization: the phenomenon of monomoraic vowel lengthening in Japanese. Japanese phonology requires prosodic words to be minimally bimoraic (i.e., one foot) (e.g., Poser, 1990; Itô, 1990; Itô & Mester, 1992)—a requirement which is responsible for shaping many morphophonological patterns. Because of this prosodic restriction, Japanese monomoraic nouns, when produced in isolation, are lengthened (Mori, 2002). Our experiment shows that, despite this phonological lengthening, the contrast between lengthened monomoraic nouns and underlyingly long nouns is not completely neutralized at the surface phonetic level. This study thus contributes to expanding the typology of incomplete neutralization.