This thesis examines the issue of descriptive adequacy in theories of the phonology and phonetics of intonation and tone. It is argued that in order to account for certain robust phonetic facts, such as the consistent presence and timing of F0 peaks and valleys across languages (Ladd 1996), theories of the phonology and phonetics of tone and intonation must crucially specify the relative height relations of tones. For languages with lexically unconstrained placement of tones within the pitch range, such as English, an absence of restrictions on relative tone height is shown to lead to two types of problems: overgeneration of phonetic contours from phonological representations, and indeterminacy of phonological representations for phonetic pitch contours. It is shown that previous theories of intonation, including Pierrehumbert (1980), include insufficient constraints on relative tone height and therefore inherit these difficulties. To address these issues, it is proposed that relative height be represented in terms of structure known as a tone interval, which is an abstraction of a frequency ratio (e.g., a musical interval). A tone interval encodes the relative height and/or the size of the interval between a tone and one of two types of construct: a referent tone, or a referent pitch level. In this way the proposal builds on work in auditory perception and cognition showing that musical melodies are represented in terms of relative height relations between notes or between a note and a referent pitch level, i.e., the musical key.
Six experiments tested the predictions of this theory for English. Experiments 1 and 3 involved discrimination of pairs of stimuli in which the timing of an F0 peak or valley had been varied along a continuum with respect to segments, while Experiments 2 and 4 involved imitation of these stimuli. Finally, Experiments 5 and 6 involved imitating stimuli in which absolute F0 level had been varied along a continuum. Consistent with the proposed 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 F0 peak or valley was varied across a vowel onset, or (ii) the F0 level of one syllable switched from higher than another syllable to lower than that syllable. It is shown that the theoretical proposals provide an account for the experimental results, while eliminating problems of phonological
overgeneration and phonetic indeterminacy associated with previous theories.
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