Coarticulation and contrast in static and dynamic models of second formant trajectories

Real (Stevens et al., 1966) and virtual F2 locus (Sussman et al., 1991) measures are presented for Malayalam lingual plosives. We show that in distinguishing voiceless coronals (dental, alveolar, and retroflex) in VCːV sequences, F2 onsets derived from first-order locus equations (LEs) show only partial delineation of the contrast. The dental-alveolar contrast is effectively maintained, but retroflex and alveolar stops show no significant difference in F2 onset. Following Lindblom and Sussman’s (2012) examination of LEs as a measure of relative coarticulatory resistance, we report F2 slopes for the three coronal stops in VC and CV transitions to assess the implications of this metric in Malayalam. Our findings on the ordering of slope values from steepest to flattest did not follow predictions based on expectations of relative articulatory complexity; namely, alveolars generated a flatter slope than retroflexes, despite Dart and Nihalani’s (1999) demonstration that the retroflex gesture is more complex within the coronals. These results, when compared with temporal measures from exponential models of formant trajectories at consonant implosion and release (i.e., transition velocity and projected F2 locus), suggest a necessary distinction between coarticulation-based place of articulation categorization and formant transition cues utilized in maintaining stop place contrasts.