Gestural delay and gestural reduction. Articulatory variation in /l/-vocalisation in Southern British English

The vocalisation of /l/, as currently observed in Southern British English (SBE), involves weakening of the consonantal tongue tip (TT) gesture. Such weakening can be conceptualised in terms of spatial reduction, where the magnitude of the TT gesture is decreased, or in terms of temporal delay, where the tongue tip gesture occurs relatively late, sometimes becoming masked. In this paper, we use a corpus of articulatory (ultrasound) data to tease apart the relative contribution of delay and reduction in ongoing /l/-vocalisation in SBE. The most extreme case of vocalisation we observe involves deletion of the TT gesture. More frequently, we find gradient reduction in gestural magnitude, which may be accompanied by gestural delay. For one of our speakers, the TT gesture is delayed to the point of becoming covert. However, the considerable delay observed in this case is proportional to the advanced degree of gestural reduction. We argue for an interpretation where /l/-vocalisation is primarily a spatial phenomenon, and delay is mostly a secondary manifestation of weakening. We consider the significance of our findings to more abstractionist approaches, and their view of /l/-vocalisation as a categorical phenomenon.