“…Evolved from a medieval inventory which included both voiced and voiceless sibilant fricatives, i.e., /s, z, ʃ, ʒ/, modern Castilian Spanish only maintained the voiceless phoneme /s/ (Lapesa, 1942;Fradejas Rueda, 1997; the high dialectal and intra-speaker variability has been frequently addressed by Spanish phoneticians, e.g. Univaso et al, 2014;Del Saz, 2023). The voiced allophone [z] may appear in free variation before a voiced consonant in syllable codas unless in very careful speech (Schwegler et al, 2010;Harris, 1969) or, more rarely, even between vowels, especially in fast and informal speech, as attested by Torreblanca (1983; for a few areas in Central Spain.…”