In french phonology sources, one may find disagreement over how the french /s/ sound is produced: Some go for resting tip tongue behind lower teeth and the blade touches behind upper teeth, others say the tip tongue touches behind upper teeth. Can anyone describe the reason?
According to a review of the literature (see table 1.1) dating from 1991, the /s/ and /z/ phonemes are realised with:
a tip-down laminal tongue position.
The reports are evenly split between dental and alveolar for the place of articulation of /s/ and /z/, whereas /l/ is very much apical, and /t/, /d/, /n/ are reported as apical [and dental] by the majority of sources.
The study also reported that for laminal /s/ and /z/
tend to be articulated farther back in English than in French