Prestopped bilabial trills in Sangtam

This paper discusses the phonetic and phonological features of a typologically rare prestopped bilabial trill and some associated evolving sound changes in the phonology of Sangtam, a Tibeto-Burman language of central Nagaland, north-east India. Prestopped bilabial trills were encountered in two dozen words of a 500-item corpus and found to be in phonemic contrast with all other members of the plosive series. Evidence from static palatograms and linguagrams demonstrates that Sangtam speakers articulate this sound by first making an apicalor laminal-dental oral occlusion, which is then explosively released into a bilabial trill involving up to three oscillations of the lips. The paper concludes with a discussion of the possible historical sources of prestopped bilabial trills in this language, taking into account phonological reconstructions and cross-linguistic comparisons.