# More on Sibilant Devoicing in Spanish Diachrony: An Initial Phonetic Approach
## 1 Introduction
### On Sound Change  
As known, speech production entails phonetic variation, at least to a certain extent. Allophony can be conditioned by a number of factors, including speaking style, phonological context and prosodic conditions, as well as the need to guarantee communicative success by ensuring the intelligibility of the signal ([PERSON] 1990; [PERSON] 2004; [PERSON], 2012). Phonetic variation, however, needs to be correctly parsed with the appropriate phonological category. Utterances more similar to the canonical form for a category do not represent a problem for their recognition and interpretation as members of that category, but exemplars which differ from this prototype and are more peripheral in its acoustic-auditory space may be ambiguous. They may even fall in the intersection of the cloud of exemplars of neighbouring phonological categories. In these cases, reanalysis and recategorization may take place. In other words, when the listener reinterprets the non-canonical input as a different category, a sound change can be initiated ([PERSON], 2001, 2002; [PERSON], 2004; [PERSON], 1981, 2012). There are some extra factors that can favour the change. One of them is the frequency of usage: when peripheral exemplars become more frequent, they may gradually be identified as variants central to their category and bring about a displacement from central values in the cloud of exemplars: what was once regarded as canonical will no longer be considered so ([PERSON], 2001). This preference for peripheral variants can be related to the functional load of phonological contrasts: in the case of oppositions yielding a high functional load, it is important to preserve the difference between the phonological categories in order to assure communicative success. This implies the selection of phonetic variants that display greater distinction between the members of the phonological pair, speakers therefore preferring allophones with more exaggerated phonetic cues to avoid misparsing. However, in cases where the functional load is low (i.e., when the opposition is not productive), the maximization of contrast is not that important and peripheral forms can be selected without endangering communication ([PERSON] et al., 2013, p. 184). This could have been the initial step in voicing neutralization in Early Modern Spanish sibilants. Another interesting aspect of sound change which has been discussed in devoicing cases is whether it corresponds to a ignition or a fortition process. Although it has usually been associated with strengthening mechanisms ([PERSON], 1988, pp. 51-52; [PERSON], 2001, pp. 27, 43; [PERSON], 2004, pp. 110-11; [PERSON], 2015; [PERSON], 2019, p. 270), its adsorption is not always clear. [PERSON] (2019, p. 271) define lenition and fortition in articulatory terms, as a reduction or increase in the magnitude and duration of articulatory movements. As mentioned before, [PERSON] (2001, pp. 27, 43) generally considers devoicing phenomena as fortition processes, though she admits it may be a way to simplify production in certain contexts ([PERSON], 2001, p. 107), in agreement with [PERSON] (1997, pp. 494-96). Indeed, when occurring in weak prosodic positions (such as word-final or sentence-final positions), devoicing entails gesture magnitude decrease. This is also the case with neighbouring voiceless sounds. In the former case, the ultimate cause is the reduction in the transglottal air flow, which permits friction but prevents vocal-fold vibration; in the latter, less glottal adduction (a more open glottis) is responsible for unvoicing. Intervocalic unstressed contexts have been associated with hypoarticulation conditions and, therefore, with weakening processes ([PERSON], 1990, pp. 404-5; [PERSON], 2001, p. 168; [PERSON] and Easterday, 2019, p. 288). Nevertheless, in such contexts voicing is deemed to be the normal lenition phenomenon instead of devoicing, which has been regarded as a case of strengthening ([PERSON], 1988, pp. 51-52; [PERSON] and [PERSON], 2014).