> Spanish has an alveolar sibilant (Martínez Celdrán, Fernández
Planas & Carrera-Sabaté 2003) with a number of possible realizations
(e.g. Salcedo 2010; Zampaulo 2013). The two most important pronunciations
for the purpose of this study are: the lamino-alveolar sibilant (ese
predorsal in Spanish) [s̻ ] and the apicoalveolar sibilant [s̺]
(ese castellana). The former is produced with the tongue blade making
light contact with the alveolar ridge. A groove is formed along the
surface of the tongue through which air passes producing noisy sibilance