Acoustic correlates of flaps in North American English

Abstract

Using Brightness and Motion mode ultrasound, Derrick and Gick (2011, CJL) identified four categorical variations of flap (rapid “d”-like) tongue movements produced in North American English (that is, up-flaps, down-flaps, alveolar taps, and postalveolar taps). These variants can be used to test hypotheses about constraints on speech articulation, such as local context, gravity and elasticity, speech rate, and longer distance anticipatory coarticulation. The present study examines acoustic correlates of flap and rhotic (“r”-like) vowel variations in order to facilitate the understanding of articulatory mechanisms that underlie acoustic outputs. Understanding the relationship between articulatory mechanisms and acoustic outputs may allow us to draw inferences about articulatory mechanisms from pre-existing and future acoustic databases. Preliminary results identify significant differences in f0, F1, F2, F3, F4, and F5 values between these flap variants. In addition, we used supervised hierarchical clustering to aid in identification of flap variants based on both vocalic context and acoustic parameters. Unsupervised hierarchical clusters will also be used to identify whether the four flap variants that were previously identified in our articulatory studies are enough to capture the actual categorical variation that occurs and, if not, to identify currently unknown categories of flap variation in North American English.