The Effects of Duration and Sonority on Contour Tone Distribution—Typological Survey and Formal Analysis
This dissertation addresses two general questions in phonology: (a) Are positional prominence effects contrast-specific? (b) For a specific phonological contrast,
is its positional prominence behavior tuned to language-specific phonetic patterns?
These questions are investigated through the behavior of contour tones. Unlike many other phonological features, the production and perception of contour tones crucially depend on the duration and sonority of the rime. This provides a testing ground for whether the positional prominence behavior of contour tones is tied to its specific articulatory and perceptual needs. Furthermore, there exist multiple phonological factors that affect the duration of the sonorous portion of the rime, and the magnitudes of these effects differ on a language-specific basis. This provides a testing ground for whether the contour tone behavior of a language is tuned to its specific phonetic patterns.
In a survey of 187 languages, the distribution of contour tones is found to correlate closely with the duration and sonority of the rime. Syllables with longer sonorous rime duration, e.g., those that are long-vowelled, sonorant-closed, stressed, prosodic-final, or in a shorter word, are more likely to carry contour tones. This supports the contrast specificity of positional prominence, since the distribution of contour tones is decidedly different from that of many other phonological features, and it is tuned to the specific articulatory and perceptual needs of contour tones.
In phonetic studies of languages with the same multiple factors that induce rime lengthening, it is found that contour tones always favor the factor with the greatest
lengthening, even though different languages have different factors that induce the greatest lengthening. This is evidence for the relevance of language-specific phonetics in positional prominence.
Formal apparatus couched in Optimality Theory is proposed to account for the effects of duration and sonority on contour tone distribution. The apparatus necessarily encodes many phonetic details. But it predicts only general patterns that are attested in the survey, and it can account for both the 'phonological' effects of tone and length neutralization and the 'phonetic', albeit language-specific, effects of partial contour reduction and rime lengthening.