# More on Sibilant Devoicing in Spanish Diachrony: An Initial Phonetic Approach
## 1 Introduction
### Historical Evolution  
Medieval Spanish presented three pairs of sibilant consonants: dentoalveolar affricates /f/f, d\(\bar{2}\)/, alveolar fricatives /s, z/ and postalveolar fricatives /f, s/, plus a palatal voiceless affricate /f/f.2 The voiced counterparts arose from a voicing process in Late Latin in intervocalic context ([PERSON] 1981, p. 124; [PERSON] 1993, pp. 238-40, 389, 423; [PERSON] 2004, pp. 834-35). Devoicing would have taken place in the 15 th to 16 th centuries ([PERSON] 1967, p. 312; [PERSON] 1981, p. 283; [PERSON] 1987, p. 59; [PERSON] 1993, pp. 427-28; [PERSON] 2004, pp. 833-34; [PERSON] 2012, pp. 222-23; [PERSON] 2014, pp. 121-22). However, there issome evidence that the confusion initiated much earlier, in the 13 th ([PERSON] 2004, p. 442, regarding the dentoalveolar pair) or 14 th centuries ([PERSON] 2004, pp. 603-4); in fact, [PERSON] (2005, pp. 270-71) points to an ancient phenomenon. In any case, orthographic errors in Medieval texts point to a primary confusion between the result of dentoalveolar deaffrication (/fs, d\(\tilde{z}\)/>/s, g/), which would have induced devoiting in the fricative pairs ([PERSON] 1987, p. 58; [PERSON] 1981, p. 283; [PERSON] 2005, pp. 168-69; [PERSON] 2012, p. 224).3  
As we have said, voiced-voiceless pairs were only contrastive in medial intervocalic position, while only voiceless siblants were possible in word-initial and coda positions, except for the postalveolar pair (/_f_, _s_/), which also contrasted in word-initial position. Some researchers suggest an intermediate stage in which word-final siblants in prevocalic context would also have been voiced before devoicing was completed ([PERSON] 1993, p. 80; 2006, pp. 22-23), as occurs in other Romance varieties, such as Catalan or Italian dialects. Even some modern varieties of Spanish, such as highland Ecuadorian Spanish, display this behaviour (see [PERSON] 1989 for a detailed description). The devoicing process has been considered a rare evolution within the Western Romance varieties by some scholars ([PERSON] 1988, pp. 51-52; [PERSON] 1993, p. 428), since in such a context voicing would be expected ([PERSON] 2015; [PERSON] 2016, p. 37) and it is this atypical evolution that has sparked interest in the topic. The literature has put forward different explanations for it, which range from language contact to aerodynamic reasons. The most traditional accounts attribute devoicing to (a) the influence of Basque, which lacked voiced siblants ([PERSON] 1951-1952; [PERSON] 1993, pp. 429-37), (b) a readjustment of the system to improve its efficiency, since voiced-voiceless oppositions were not productive enough ([PERSON] 1988, pp. 51-53; [PERSON] 1993, pp. 81-82; [PERSON] 2012, p. 224) or (c) a readjustment of the system aiming at a more perfect symmetry, since /t\(\tilde{\text{f}}\)/ did not have a voiced counterpart ([PERSON] 1951, pp. 179-80). [PERSON] (1993) deals with these approaches and her conclusion is that neither language contact nor structural accounts seem to be completely satisfactory. Moreover, she argues that they are unnecessary since internal phonetic factors can justify the change. [PERSON] shows that siblant devoicing is not unique to Spanish (cf. [PERSON] et al. 2012 for a detailed explanation of the infrequency of voiced siblants in the world's languages) and that, in the world's languages, this process usually begins with a specific pair, usually palatal or dentoalveolar affricates. Affricates tend to devoic before fricatives, and palalds do so before than alveolars. However, [PERSON] (1993) was not the first to point to phonetic causes. [PERSON] (1967, p. 313) also referred to the intrinsic properties of siblants. The important issue here is that voiced siblants need to ensure simultaneous vocal-fold vibration and turbulence, which is not a simple task, due to the required aerodynamic conditions (broadly speaking, intraoral pressure must be less than subglottal pressure but higher than exterior pressure to maintain both mechanisms, cf. [PERSON] 1993, pp.