This dissertation addresses the methodology used in classifying speech rhythms in order to resolve a long-standing linguistic conundrum about whether languages differ rhythmically. There is a widespread perception, both among linguists and the general population, that some languages are stress-timed and others are syllable timed. Stress-timed languages are described as having less-regular rhythms, as syllable durations vary according to the placement of stress in the phrase. Meanwhile, syllable-timed languages are described as displaying less variation in rhythm, which syllable durations being more regular. This dissertation quantitatively evaluates these described rhythmic differences in Spanish, Portuguese, and English. The first chapter introduces speech rhythms and reviews past literature on their perception and production.

The second chapter evaluates a widely used metric of speech rhythms, the PVI, and determines that it is not effective in distinguishing between two dialects of Spanish. The third chapter compares the speech rhythms of Mexican and Chicano Spanish. This chapter concludes that Chicano Spanish is more restricted in its vowel duration variability, while Mexican Spanish employs both highly variable durations (i.e. stress-timed) and highly uniform durations (i.e. syllable-timed). The chapter describes a perception study used to compare the speech rhythms of Spanish, English, and Portuguese, and shows that these languages' rhythms do not always group according to language. In the fifth chapter, I describe a study of the production of the same utterances initially used in the perception experiment; this allows an analysis of what prompts the perceptual differences in speech rhythm described in Chapter Four.

The sixth and final chapter discusses the implications and applications of these findings and gives direction for further investigation. Although both production and perception studies of speech rhythms have been performed in the past, my dissertation expands these methodologies by combining production and perception data is a single analysis. I use perception data to relatively classify the rhythms of utterances through low-pass speech filtering, then analyze the production of these data computationally to provide a more complete perspective of what prompts differences in speech-rhythms and how Spanish, Portuguese, and English data relate rhythmically. Thus, my dissertation is thorough, while still addressing traditional rhythm metrics and employing current computational methodology. It seeks to challenge linguists' methodologies in quantitatively addressing speech rhythms, and to further clarify the position of Spanish, Portuguese, and English on the speech rhythm continuum.