This dissertation constitutes the first description and analysis of the tone system of Cua, a highly endangered and underdocumented Kalahari Khoe language of the Tshwa subgroup spoken in southeastern Botswana. This dissertation includes (i) an updated phonological sketch of Cua, including evidence of segmental contrasts and phonotactic constraints, (ii) an empirical overview of Cua’s tonal inventory, tonal phenomena, and tonal morphophonology, (iii) the results of a phonetic study on lexical tone in Cua conducted with 6 Cua speakers, and (iv) a phonological analysis of Cua tone which proposes phonological representations of Cua’s lexical tonal categories and derivations of tonal phenomena noted throughout the preceding chapters.
With a segmental inventory comprising 95 contrastive phonemes (33 pulmonic consonants, 52 non-pulmonic consonants, 5 oral vowels, 3 nasalized vowels, 2 pharyngealized vowels) and at least 9 contrastive lexical tone categories ‹HH, HM, HL, MM, LL, LM, dHH, dHM, dHL›, Cua occupies an upper bound of phonological complexity found in human language. This study shows that Cua’s tone categories are realized as complex f0 curves, yet despite the apparent crowdedness of Cua’s tonal space and the realization of tone as complex f0 curves, I propose a decompositional analysis of Cua’s tonal categories in terms of 4 contrastive tone heights: /H, M,ꜛL, L/. I also present evidence of tone-spreading effects, language-specific intonational effects which affect the phonetic realization of underlying tones, and positional licensing constraints which privilege tonal contrasts in the first mora of lexical roots.
Compared to related Kalahari Khoe languages, which have been analyzed as three-tone systems, the proposed analysis of Cua as a four-tone system is the innovative result of the phonologization of tonal depression. The phonologization of tonal depression in Cua has triggered the genesis of three new tone categories ‹dHH, dHM, dHL›, as well as the genesis of a novel fourth contrastive tone height, ‘raised Low’ /ꜛL/.
Tonal depression in Cua involves a typologically rare non-natural class of depressor consonants including: voiced obstruents, voiceless aspirated obstruents, nasal (or ‘delayed’) aspirated clicks, and the glottal fricative /h/. This study proposes that the phonologization of tonal depression took place as (i) insertion of a root-initial /L/ tone, which (ii) was reanalyzed as the floor of the tonal space, and (iii) triggered concomitant ‘counter-depressant raising’ of former *L-initial tone categories to a novel fourth contrastive height, /ꜛL/. I also report evidence for distinguishing between phonetic depression and phonologized depression in Cua.
This work has implications for (i) comparative research on Kalahari Khoe languages and the Tshwa subgroup, (ii) cross-linguistic theories of tonal diachrony, tone shift, tonogenesis, and the Tonal Comparative Method (Dockum 2019), (iii) typologies of tonal depression, (iv) phonological representations of tone, and (v) work at the phonetics-phonology interface and theories of phonologization.