6th Febraury SSF talk by Dr Chris Carignan

Talk abstract:

One of the primary challenges facing speech articulation researchers is obtaining, quantifying, and interpreting data that capture both the spatial and temporal complexity of speech production. Imaging technologies such as real-time magnetic resonance imaging (rt-MRI) yield maximal spatial information about the vocal tract. However, creating metrics from the images that are both phonetically interpretable and statistically testable is less than straightforward. In this talk, I present a method of using generalized additive mixed models (GAMMs) to analyze mid-sagittal vocal tract data obtained from rt-MRI video of speech production. Applied to rt-MRI data, GAMMs allow for observation of factor effects on vocal tract shape throughout two key dimensions: time (vocal tract change over the temporal course of a speech segment) and space (location of change within the vocal tract). Examples of this method are provided for rt-MRI data collected at a temporal resolution of 20 ms and a spatial resolution of 1.41 mm, for 36 native speakers of German. Three test cases are provided as a way of observing vocal tract differences between: (1) /aː/ and /iː/, (2) /aː/ and /aɪ/, and (3) accentuated and unstressed /aː/. The results for each GAMM are independently validated using functional linear mixed models (FLMMs) constructed from data obtained at 20% and 80% of the vowel interval. I will also highlight an extension of the method to acoustic analysis by applying GAMMs to spectral energy of fricatives.