Revisiting the role of the sublingual cavity in the /s/‐/∫/ distinction.

The sublingual cavity (SC) has been shown to play an important role in shaping the spectra of consonants, potentially distinguishing /s/ from /∫/. This work reports on acoustic‐articulatory experiments using MRI and mechanical modeling designed to investigate the details of how the SC acts as an acoustic filter and whether it also affects the aeroacoustic source in fricative production. Five American English subjects were imaged while producing fricatives in various vowel contexts. Two subjects that show opposite patterns were studied in detail. In M1, the /s/‐/∫/ distinction is mainly carried by SC presence and lip protrusion in /∫/ versus absence in /s/, resulting in marked spectral differences. M2 exhibits significant variability in SC shape and size, and tongue and lip position, in both fricatives; the acoustic spectra likewise vary. Mechanical model experiments show that the noise generation changes as the sublingual cavity is filled in. The main resonance frequency does not necessarily change. It seems thus that the sublingual cavity is just one of many articulatory variables available to the speaker and may not be the principal cause of observed acoustic differences in all subjects. [Work supported by NIH NIDCD DC 006705 to Haskins, NIH NIDCD T32 DC00038 to MIT‐SHBT.]