Tonal contrasts and initial consonants: a case study of tamang, a 'missing link' in tonogenesis

Tamang (Bodic division of Tibeto-Burman) is spoken at the edge of the East Asian 'tone-prone' zone, next to the almost tone-free Indian linguistic area, and is, chronologically, at the late end of the tone multiplication wave which has swept through East Asia in the course of the last two millennia. It can be regarded as a 'missing link' in tonogenesis: following the loss of voicing contrasts on syllable-initial consonants, Tamang has four tonal categories instead of its earlier two-tone system; the present state of the prosodic system is typologically transitional, in that these four tonal categories are realised by several cues which include fundamental frequency (F(0)), phonation type, and allophonic variation in the realisation of consonants. Acoustic and electroglottographic recordings of 131 words in two carrier sentences by 5 speakers were conducted (total number of target syllables analysed: n = 1,651). They allow for a description in terms of F(0), glottal open quotient, duration, and realisation of consonants. The results confirm the diversity of cues to the four tonal categories, and show evidence of laxness on tones 3 and 4, i.e. on the two tones which originate diachronically in voiced initials. The discussion hinges on the phonological definition of tone.