Simulating vowel chain shift in Xumi

• Our study is an example of interaction between computer modeling and linguistic data.
• We model a synchronic vowel chain shift in Xumi (Tibeto-Burman).
• We test one specific hypothesis and general issues related to synchronic chain shifts.
• We demonstrate the effect of self-organization in relation to a real-world language.

This paper presents a simulation study of a vowel chain shift in Xumi (Tibeto-Burman). It adapts de Boer, 2000 and de Boer, 2001 model of vowel systems in a population of artificial agents. The goals are: (1) to test one specific hypothesis of the relevance of a loan phoneme to the observed changes in the chain shift, and (2) to address on the basis of our Xumi data some general questions of interpretation related to synchronic vowel chain shifts. Our simulation results shed light on a complex scenario of change in Xumi that involves both system-internal factors and a system-external factor (the addition of a loan phoneme). Our simulation results also suggest that the particular combination of mechanisms and constraints in the model's settings—random acoustic noise, self-organization, and contrast maintenance—is a viable hypothesis for vowel chain shifting. Our study demonstrates that computational simulations are helpful in evaluating different approaches to a specific instance of sound change.