Overview

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 TT gesture occurs relatively late, sometimes becoming masked. In this chapter, 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.

Introduction

The vocalisation of /l/ in Southern British English (SBE) is an example of a weakening change, in which the consonantal tongue tip (TT) occlusion is lost. Such loss is assumed to be phonetically gradual, and can be straightforwardly modelled in spatial terms as an incremental reduction of the degree of constriction. However, the loss of constriction can also be modelled in terms of articulatory delay, where the TT gesture is present, but it occurs relatively late, such that acoustic consequences of TT contact are not realised. The role of gestural delay in conditioning /l/-vocalisation is acknowledged by previous studies (e.g. Browman and Goldstein 1992; Gick 1999; Tollfree 1999), but it is not fully understood. We do not know whether gestural delay is an independent mechanism in /l/-vocalisation, or whether it is strictly tied to specific degrees of gestural reduction. We address this issue in the present chapter, looking at the relative contribution of delay and reduction in advanced and incipient /l/-vocalisation in SBE, using ultrasound data from a previously collected corpus (Strycharczuk and Scobbie 2015, 2016).