Synchronic variation in the articulation and the acoustics of the Polish three-way place distinction in sibilants and its implications for diachronic change

The aim of the present study was to relate articulatory properties of the Polish sibilants /s ʂ ɕ/ to a potential neutralization of /ʂ/ as either /s/ or /ɕ/, the former having occurred in a number of Polish dialects. For this purpose tongue tip (TT) movement data was obtained together with acoustic data using electromagnetic articulography. The sibilants, that were always followed by either /a e o/, were produced by four L1-Polish speakers at fast and slow speech rates. While /s ʂ/ had almost identical transitions, they differed greatly in the spectral characteristics with /ʂ/ being closer to /ɕ/. In order to capture differences in tongue position as well as shape both TT position and TT orientation data were analyzed. The vertical TT orientation showed similarities in /ʂ/ and /s/ production, but the two sibilants were clearly separated in TT position, with /ʂ/ being produced far more back than /s/ and /ɕ/, and the latter two being very similar. The tendentially greater effect of speech rate on /ʂ/ together with the varying acoustic and articulatory similarities between the sibilants are taken as an indicator for greater instability of /ʂ/. This synchronic instability is discussed in terms of potential diachronic mergers.