The aim of the following study is to verify to what extent the voiced variant [z] is increasingly spreading into the north-western Tuscan territories. This variant is typical of northern Italy varieties but it has also been recently found within Florentine speech, whereas a research on the north-western part of Tuscany has not been conducted up to now. This paper presents therefore the results of a sociophonetic analysis of intervocalic /s/ as it is realised in the regional Italian spoken in Livorno. Moreover, the following research aims to verify if [z] selection is determined according to gender and social class. Preliminary results show that gender seems to be the parameter which mostly influences the phonetic realization of /s/.