Locus Equation Analysis as a Tool for Linguistic Fieldwork

Locus equations are linear regressions based on F2 formant transitions from vowel onsets to vowel midpoints. The F2 value of the onset of a given vowel can be plotted on the y-axis, with the F2 for the vowel’s midpoint plotted on the x-axis. Locus equations are derived from numerous F2 onset-F2 midpoint plots of this type. Each locus equation is associated with a particular consonant, which precedes the particular vowel tokens plotted according to F2 transition. Locus equations provide data on the patterns of CV coarticulation characterizing particular consonants. Studies in laboratory settings have demonstrated the efficacy of locus equation analysis for exploring such coarticulation patterns. However, locus equation analysis has generally not been exploited as a tool for linguistic fieldwork. This study presents an exception, as the author presents various locus equations based on data from Karitiâna, an endangered Amazonian language. These equations, based on acoustic data gathered in the field, reveal language-specific patterns of coarticulation. The results suggest that, even in remote non-laboratory settings, locus equations can be applied in a straightforward manner in order to provide useful insights into a language’s sound system.