Principal components analysis of tongue shapes in symmetrical VCV utterances

Current accounts of speech motor control do not predict tongue movement during labial stops in symmetrical VCV sequences. Nevertheless, there is clear evidence that such movement does occur. A Principal Components analysis was performed on X-ray data from a Swedish speaker. For all vowel contexts, it revealed that, as articulation approached the VCVs intervocalic consonant, the tongue contour tended to change in the direction of a more neutral shape. On the basis of this result (and previous findings) we suggest that the so far unexplained tongue movement (the 'trough' effect) should be seen as a de-activation of V1 activity during the consonant closure and before the onset of V2. The theoretical implication of that view is that VCV sequences should be reinterpreted as produced in a phoneme-by-phoneme fashion rather than as combining a diphthongal movement of the tongue body articulator from V1-to-V2 with a superimposed movement associated with the intervocalic consonant. Theories of coarticulation must be re-written accordingly.