The development of in Tibetic languages: Assessing sound change pathways and functional load

Old Tibetan is attested through texts in the late first millennium (7th - 9th c. CE; Bialek, 2022) and considered the common ancestor of modern Tibetic languages. Old Tibetan is phonologically distinctive for preserving complex consonant clusters in syllable onsets (e.g. <bsgrubs> ‘completed’), which have been reduced in modern Tibetic languages in different amounts (modern reflexes of <bsgrubs> include /ɣɖʐəp/ and /˨ʈup/; Bielmeier et al, 2018: 224).

My research focuses on the development of <zl>, which has the reflex /˨(ⁿ)t/ in modern Lhasa Tibetan (‘Standard Tibetan’), in words such as <zla-ba> ‘moon’ /˨(ⁿ)ta.wa/ (Gong, 2016). It is non-obvious how to derive /ⁿt/ from /zl/ using established sound changes in the historical linguistics literature, suggesting that this change involved multiple steps and possible interaction with other clusters in Tibetic as different clusters all underwent reduction.

Many researchers have proposed possible changes linking <zl> to its modern-day reflexes (incl. Sprigg, 1972; Beyer, 1992; Gong, 2016; Bialek, 2018), but there is so far no work in the literature systematically assessing and comparing these proposals. Therefore, I assess several existing proposals for the sound change <zl> > /ⁿd/ based on their phonetic plausibility, and their ability to account for attested reflexes of <zl>, including /lz, ldz, ld, hrz/ as well as /˨(ⁿ)d/ (Bielmeier et al, 2018). The phonetic assessment considers the sound change proposals with reference to recent literature on sound change in broader historical linguistics, including work on the phonetics of laterals (Tunley, 1999; Round, 2014), metathesis (Blevins & Garrett, 2004; Finley, 2017), and fortition (Bybee & Easterday, 2019). This thus produces the first systematic assessment of different proposals for <zl> > /˨(ⁿ)d/ in the Tibetan historical phonology literature.

Nikolaev (2020) recommends using functional-load based approaches to account for changes to <zl> alongside phonetic approaches, so I also provide a functional-load driven analysis of <zl> inspired by recent work on the role of functional load in phonological mergers (incl. Babinski & Bowern, 2018; Wedel et al, 2013). The literature generally agrees that <zl> merges with <ld>, ultimately giving rise to /˨(ⁿ)d/ (Gong, 2016); however, all other <Cl> clusters in Old Tibetan merge with each other, producing /˦l/ in Lhasa Tibetan. I consider the minimal pair count distinguishing the consonant clusters in question, and the relative token frequencies of all the clusters involved, and conclude that <zl> merged with <ld> because they are not used to contrast any minimal pairs (Monlam, 2020), and both have low token frequencies in the attested Old Tibetan corpus (Takeuchi et al, 2006). Even though this study is narrow in scope, it marks an early example of using functional load to explain sound change in Tibetic languages.

REFERENCES

Babinski, S., & Bowern, C. (2018). Mergers in Bardi: Contextual probability and predictors of sound change. Linguistics Vanguard, 4(s2). https://doi.org/10.1515/lingvan-2017-0024

Beyer, S. V. (1992). The Classical Tibetan language. Albany: State University of New York Press.

Bialek, J. (2018). The Proto-Tibetan clusters sL- and sR-and the periodisation of Old Tibetan. Himalayan Linguistics, 17(2). https://doi.org/10.5070/h917238831

Bialek, J. (2022). A textbook in Classical Tibetan. Routledge.

Bielmeier, R., Driem, G. L. van, & Volkart, M. (2018). Comparative Dictionary of Tibetan Dialects (CDTD). Volume 2: Verbs. De Gruyter. https://doi.org/10.1515/9783110554076

Blevins, J., & Garrett, A. (2004). The evolution of metathesis. In B. Hayes, R. Kirchner, & D. Steriade (Eds.), Phonetically based phonology (pp. 117–156). Cambridge: Cambridge University Press. https://doi.org/10.1017/cbo9780511486401.005

Bybee, J., & Easterday, S. (2019). Consonant strengthening: A crosslinguistic survey and articulatory proposal. Linguistic Typology, 23(2), 263–302. https://doi.org/10.1515/lingty-2019-0015

Finley, S. (2017). Learning metathesis: Evidence for syllable structure constraints. Journal of Memory and Language, 92, 142–157. https://doi.org/10.1016/j.jml.2016.06.005

Gong, X. (2016). Prenasalized reflex of Old Tibetan and related clusters in Central Tibetan. Cahiers de Linguistique Asie Orientale, 45(2), 127–147. https://doi.org/10.1163/19606028-00452p02

Monlam, L. (2020). Monlam Grand Tibetan Dictionary. List of lemmas curtesy of Dr Marieke Meelen.

Nikolaev, D. (2020). On the sound change *ld > nd in Tibetic. Cahiers de Linguistique Asie Orientale, 49(2), 250–255. https://doi.org/10.1163/19606028-bja10007

Round, E. (2014). Prestopping of nasals and laterals is only partly parallel. In R. Pensalfini, M. Turpin, & D. Guillemin (Eds.), Language description informed by theory (pp. 81–95). Amsterdam: John Benjamins.

Sprigg, R. K. (1972). A Polysystemic Approach, in Proto-Tibetan reconstruction, to tone and syllable-initial consonant clusters. Bulletin of the School of Oriental and African Studies, 35(3), 546–587. https://doi.org/10.1017/s0041977x00121160

Takeuchi, T., & collaborators. (2006). Old Tibetan Documents Online (OTDO). Retrieved January 1, 2023, from https://otdo.aa-ken.jp

Tunley, A. (1999). Coarticulatory influences of liquids on vowels in English (PhD Thesis). University of Cambridge.

Wedel, A., Jackson, S., & Kaplan, A. (2013). Functional load and the lexicon: Evidence that syntactic category and frequency relationships in minimal lemma pairs predict the loss of phoneme contrasts in language change. Language and Speech, 56(3), 395–417. https://doi.org/10.1177/0023830913489096