Increasing Periodicity to Reduce Similarity: An Acoustic Account of Deassibilation in Rhotics

Alternations and changes from trills to assibilated rhotics have been documented in several Latin American Spanish varieties (e.g. Vidal de Battini 1955, Rissel 1989). Beyond the sociolinguistic variables that may have triggered this change, assibilation can be accounted for by recent articulatory studies on trills (Solé et al. 1998, Solé 2002). These studies show that trills require very precise aerodynamic conditions for their production, and if those conditions are not met, and oro-pharyngeal pressure increases, an assibilated rhotic is produced instead. The change in the opposite direction, which is the one that concerns us here, should be less likely, since speakers would have to learn to master, among other parameters, the necessary aerodynamic conditions to produce a trill. However, this process has also been documented, again triggered by specific sociolinguistic conditions (e.g. De los Heros 1997, Colantoni 2001). Given the seemingly equal likelihood of the bi-directionality of the process, several explanations are possible. It could be hypothesized either that the sociolinguistic factors override the phonetic motivations or that the articulatory studies are not accurate. A third hypothesis will be proposed here, namely that it is not the trill but rather an approximant rhotic that is the end-point of this process. Approximants differ from fricatives in the absence of a turbulent airstream, which could be due to: (i) a lack of the articulatory precision required to produce a fricative; (ii) an insufficiently narrow constriction; (iii) a combination of (i) and (ii) (Martínez Celdrán 2004: 208). As such, a change from an assibilated to a non-assibilated rhotic involves an increase in periodicity that is achieved by decreasing the degree of constriction. Loss of assibilation in rhotics, illustrated in (1), is then, the mirror image of another change that is taking place in some areas of Argentina (e.g. Corrientes, Cordoba, Entre Rios), including some of the locations under study. There the existing non-assibilated palatals are being substituted by assibilated post-alveolars, as shown in (2) below: