A puzzling issue of linguistic theory is how humans map speech, which is characterized by notable diversity, into abstract linguistic categories. I explore the extent to which both phonological and phonetic models and machine learning methods, such as deep neural architectures, can offer insights into the cognitive foundations of speech that make this mapping possible. In the following, I organize my research into four projects.
The Phonology of Prosody
Prosody refers to the melodic patterns of speech. The melodic units of speech are characterized by continuous dynamic properties. A long-standing problem in phonology of prosody is to provide a formal definition of the units, a.k.a., pitch accents that make up the melodic pattern of speech, a.k.a., intonation. A relevant problem in phonological theory is how pitch accents are timed with respect to vowels and consonants. Several hypotheses were proposed that aim to define the timing of pitch accents with the segmental structure. By exploring the timing of the Cypriot Greek L*+H prenuclear pitch accent, in Themistocleous (2016), I investigated the predictions of three hypotheses: the invariance hypothesis, the segmental anchoring hypothesis, and the segmental anchorage hypothesis using two experiments: the first of which manipulates the syllable patterns of the stressed syllable, and the second modifies the distance of the L*+H from the following pitch accent. In the study, I show that the findings on the alignment of the low tone (L) corroborate the predictions of the segmental anchoring hypothesis: the L persistently aligns inside the onset consonant, a few milliseconds before the stressed vowel. However, the findings about the alignment of the high tone (H) are both intriguing and unexpected: the alignment of the H depends on the number of unstressed syllables that follow the prenuclear pitch accent. The ‘wandering’ of the H over multiple syllables is extremely rare among languages, and casts doubt on the invariance hypothesis and the segmental anchoring hypothesis, as well as indicating the need for a modified version of the segmental anchorage hypothesis. To address the alignment of the H, we suggest that it aligns within a segmental anchorage–the area that follows the prenuclear pitch accent–in such a way as to protect the paradigmatic contrast between the L*+H prenuclear pitch accent and the L+H* nuclear pitch accent.
Another relevant issue of the phonology of intonation is the formal description of pitch accents that make up the phonemic inventory of a language or dialect. Themistocleous (2011b) provides the first description of Cypriot Greek pitch accents and compares their production with those of Standard Modern Greek. Specifically, Themistocleous (2011) provides a model of prenuclear and nuclear pitch accent accents of Cypriot Greek. He also shows that there is significant dialectal variation in the realization of pitch accents with respect to their alignment and pitch range. Overall, Themistocleous (2011) provided a model about the way pitch accents manifest categories of information structure, namely information focus, topic, contrastive focus, and contrastive topics (see also Themistocleous, 2012).
Prosodic structure refers to the phonological constituents of prosodic hierarchy, such as the syllable, the foot, the phonological words and intermediate and intonational phrase. These phonological constituents account for various phenomena that take place at their edges, one of these phenomena is final lengthening. In Themistocleous (2014), I conducted two experiments that investigate the interaction of edge-tones and final lengthening. The study shows that in Cypriot Greek the following occur: (a) lengthening applies primarily on the syllable nucleus not the syllable onset, which suggests variety specific effects of lengthening; (b) lengthening depends on the edge-tones, namely, polar questions trigger more lengthening than statements and wh-questions; (c) lengthening provides support for at least two distinct prosodic domains over the phonological word, the intonational phrase and the intermediate phrase; greater lengthening associates with the first and shorter lengthening with the latter; (d) finally, syllable duration depends on the syllable distance from the boundary, i.e., lengthening locally applies on penultimate and ultimate syllables whereas antepenultimates are affected the least. Additionally, by pointing to the distinct lengthening effects of edge-tones and domain-boundaries, the findings provide evidence for dinstinct lengthening devices.