Dynamic blending and assimilation in Catalan lingual fricative sequences. An ultrasound and acoustic study

Abstract Ultrasound and center of gravity frequency data for the sequences /ʃ#s/ and /s#ʃ/ produced by Central Catalan speakers reveal that the former sequence is implemented through continuous articulatory and spectral trajectories which, depending on speaker, may be: intermediate between /ʃ/ and /s/ all throughout, thus supporting a dynamic blending mechanism; /ʃ/-like at onset and intermediate between the two fricatives at offset, which is indicative of C1-to-C2 carryover coarticulation. The sequence /s#ʃ/, on the other hand, undergoes regressive assimilation into ʃ(ʃ) according to the acoustic signal but less clearly so in the light of the articulatory data. This discrepancy appears to be due to the fact that, while C1=/s/ assimilates indeed to C2=/ʃ/ at constriction location, coarticulation-induced changes in tongue body configuration behind the primary articulator may occur as long as they do not jeopardize the front-cavity dependent frequency characteristics of the ʃ frication noise. Differences in articulatory complexity between /ʃ#s/ and /s#ʃ/ appear to result from the production mechanisms involved, i.e., tongue dorsum raising behind the /s/ constriction for /s#ʃ/ and tongue body repositioning for /ʃ#s/. In agreement with this interpretation, /ʃ#s/ but not /s#ʃ/ turned out to be longer than /s#s/ and /ʃ#ʃ/.