Acoustic properties of Mexico City Spanish vowel weakening

Abstract

Mexico City Spanish exhibits weakened vowels that have been described as reduced, relaxed, unstable, obscured, abbreviated, devoiced, and “lost,” indicating likely reduction in duration, voicing, and/or quality. The objective of this study is to precisely identify the acoustic nature of this vowel weakening. To this end, recorded spontaneous speech was collected from 20 speakers native to Mexico City. 3000 tokens, i.e., monophthongs, were analyzed acoustically in Praat (Boersma & Weenink 2016), and measurements were taken for F1, F2, vowel duration, and voicing duration. Findings show that vowel weakening in this variety consists primarily of shortening and weakened voicing, but not raising or centralization. Instead of simple presence or absence of voicing, many tokens show weak voicing, characterized by a lower intensity in the waveform and a lighter voice bar, or partial voicing that does not endure throughout the entire vowel. The presence of frication distinguishes devoicing from weak voicing when other aspects of the acoustic signal are not clear indicators. Many tokens exhibited full voicing, but only consisted of 2-3 wave cycles, resulting in a severely shortened vowel. Uncovering the acoustic properties of these weakened vowels is crucial to understanding how this variety fits with cross-linguistic vowel weakening trends.