# More on Sibilant Devoicing in Spanish Diachrony: An Initial Phonetic Approach
## 1 Introduction
### Obstment Devoicing Process  
One of the main objections by [PERSON] (1993) to the classical analysis is that she rejects the idea of devoicing as an atypical evolution for siblants. Obstruent devoicing has been widely attested, described and explained not only in coda position but also in word-initial context ([PERSON] 2001, pp. 27, 43; [PERSON] and [PERSON] 2001; [PERSON] 2004, pp. 103-6, 110-11; [PERSON] 2015, pp. 142, 169-71).5 When examining the inventories of obstruent elements in the world's languages, the general impression is that voiced segments are not common ([PERSON] 1997, p. 473; [PERSON] and [PERSON] 2010, p. 53; [PERSON] et al. 2012). Indeed, since the aerodynamic requirements for producing them are more complex, contrasts may be lost by means of various phonological processes whose result is a reduction in the number of voiced units ([PERSON] and [PERSON] 2010, pp. 53-54; [PERSON] et al. 2012, pp. 308-9, 313; [PERSON] and [PERSON] 2014, p. 111). These mechanisms include changes to a voiced fricative (in the case of affricates) or a glide, defrication, vocalization, and, of course, devoicing. Take special note that devoicing affects sibilants differently depending on their context. [PERSON] (1978) shows that fricatives are more likely to devoice when followed by a voiceless stop or even a voiced stop than in intervocalic position; and word-final position also seems to favour devoicing. [PERSON] (1997), in her survey on /z/ devoicing in American English, corroborates this. Her data show that /z/ can devoice in any position, but the extent and the likelihood of the process vary depending on the neighbouring sounds and prosodic structure: a following voiceless sound and a final position in the prosodic domain increase the likelihood of devoicing. These findings are coherent with the general picture on obstruent devoicing presented above. At this point, we must introduce some remarks on what devoicing implies from a phonetic point of view. Obviously, devoicing entails a reduction in vocal-fold activity,6 but it also involves other relevant parameters. Experiments in production and perception point to intensity, degree of glottal tone, F1 transitions and, specifically, duration ([PERSON] 1995, pp. 38-39; [PERSON] 1997, p. 473; [PERSON] 2001, p. 107; [PERSON] and [PERSON] 2006, p. 31): voiceless sibilants are usually longer and more intense, with short F1 transitions and no glottal vibration (or, at least, not constant glottal vibration). In fact, there is evidence that vocal fold vibration is not constant for the whole duration of voiced sibilants ([PERSON] 1978; [PERSON] 1993, p. 216; [PERSON] 1995, p. 38; [PERSON] 1997, p. 260; [PERSON] and [PERSON] 2010, pp. 71-73; [PERSON] 2016). [PERSON] (1997) observes that a large proportion of /z/ utterances in her experiment were partially devoiced (she considers as partially devoiced all cases in which voicing covers a range from 25% to 90% of the sound). Similar results are found in [PERSON] and [PERSON] (2001), who examined the devoicing of /v, z, g/ in two varieties of Dutch. However, in spite of partial devoicing, listeners are able to parse the stimuli with a voiced phonological category ([PERSON] 1995, 1997, p. 260; [PERSON] 2001, p. 107), since they may ignore this cue and rely on other indicators to repair the ambiguity ([PERSON] 1981, 2012). After examining Polish and German sibilants, [PERSON] et al. (2012, pp. 323-24) show that the voicing contrast, both in word-initial and medial positions, relies mostly on durational parameters and the measurement of intraoral pressure. Voiced sibilants display a significantly shorter duration and lower intraoral pressure peaks. Their findings are in line with the literature, which coincides in focusing on duration as a highly reliable cue for detecting devoicing ([PERSON] 1978, p. 101; [PERSON] 2001, p. 107). This phonetic description of the phenomenon needs a final comment.