The phonetics and phonology of tonal systems

Abstract

Pitch variations are used in different languages in a variety of communicative ways, from cueing lexical item identity to conveying meaning through phrasing and accentuation. Previously, linguistic theories of intonation and tone which have sought a unifying account for tonal phenomena have not defined a clear and systematic relation between phonological representations and phonetic output in terms of acoustically observable fundamental frequency (FO) variations. This is problematic, because meaningful pitch patterns cannot be related to underlying phonological primitives in any clear way, so that it is difficult to empirically verify or falsify the theory. This thesis addresses this problem by proposing a phonological description of intonation and tone for which there is a clear and systematic relationship between observed FO variations and underlying phonological primitives. The theory is based on a construct called the tone interval, which represents an abstraction of a ratio of two fundamental frequencies. A syntagmatic tone interval relates two sequentially-ordered tones, while a paradigmatic tone interval relates a tone and a speaker-specific referent level. Tone intervals define one of three relations: a tone may be higher, lower, or the same level as its referent. Additional language-specific categories may be formed which restrict the pitch distance between a tone and its referent. Tones in syntagmatic tone intervals are assumed to be arranged at the phrasal level with respect to a metrical grid, which represents the relative prominence and timing of syllables.

(cont.) This permits interactions between nonsequential tones occupying metrically prominent syllables, accounting for cross-linguistic observations involving control of relative height relations on nonadjacent syllables. Six experiments tested the predictions of tone interval theory and other phonological theories for English. Experiments 1 and 3 involved discrimination of pairs of stimuli in which the timing of an FO extremum had been varied along a continuum with respect to segments, while Experiments 2 and 4 involved imitation of these stimuli. Experiments 5 and 6 involved imitating stimuli in which absolute FO level had been varied along a continuum. Consistent with the tone interval theory, these results demonstrate the importance of relative pitch level for phonological representations. In particular, discrimination maxima and discreteness in production data were observed for positions in stimulus series in which either (i) the timing of an FO extremum was varied across a vowel onset, or (ii) the FO level of one syllable switched from higher than another syllable to lower than that syllable.