UCLA

Research in phonetics has established the grammatical status of gradient phonetic patterns in language, suggesting that there is a component of the grammar that governs systematic relationships between discrete phonological representations and gradiently continuous acoustic or articulatory phonetic representations. This dissertation joins several recent works in proposing that these relationships can be represented with constraint grammars, but moves from the harmonic grammars used in previous work to maxent grammars, already in common use by phonologists, describing how these can be adapted to the phonetic realm. Unlike existing models, maxent grammars allow phonetic variation to be modeled explicitly, outputting probability distributions over the realizations of phonetic variables instead of single values. The maxent formalism is shown to make a number of interesting empirical predictions regarding phonetic variation, defining a restrictive typology of possible phonetic patterns.

As a substantial case study, a grammar of this sort is developed for phonetic duration. Duration is known to be subject to a very large variety of (often conflicting) phonetic and phonological effects, and so this empirical domain is a rich testbed for theoretical research. A review of the empirical literature on duration is conducted, and a surprising generalization with regards to how effects on duration interact is discovered.

A production experiment on front vowel duration in English is conducted in order to shed light on how duration is computed by the grammar when multiple duration-related process are at play. The results replicate some of the interaction effects found by prior authors, and are remarkably consistent with the empirical predictions of the maxent framework in a number of respects.

Finally, a maxent learning algorithm for estimating the weights and the targets of phonetic constraints is described and implemented in Python, and this algorithm is trained, using several different constraint sets, on the data from the production experiment, yielding grammar fragments for English front vowel duration.

These endeavors serve, on the empirical side, as a new investigation of the how factors affecting duration interact and how they should modeled, and on the theoretical side as an exploration of how maxent grammars behave when they are used to model continuous phonetic variables, uncovering a powerful new tool for generative phonetics.