Deconstructing metaphony

This paper argues that the set of vowel raisings that define metaphony systems in Italian dialects, as in other Romance languages, do not result from a unified operation of height assimilation. Instead, metaphony is claimed to be the product of a restricted assimilation of high-mid vowels, and a subsequent vowel shift that conditions both the vowel raising and fronting. Low-mid and low vowels raise to fill in the gap created by assimilation of /e, o/ to /i, u/. This analysis accounts for striking parallels between the pattern of vowel movement found in diachronic vowel shift systems, as documented by Labov (1994), and the movement of vowels in metaphony systems. The proposed analysis appeals directly to acoustically-defined categories of vowel height, and avoids many problems encountered in existing analyses, which attempt to unify all metaphonic raising through the mechanism of a unified stepwise raising process that operates in terms of abstract phonological height features. The contrast-preserving nature of vowel shift is expressed through two constraints that function to preserve the underlying system of contrast by preserving constrastive height features and the relative height relations between contrastive vowels that undergo metaphonic raising.