The focus of EVOTONE is on the origin, acquisition, and evolution of linguistic tone: the use of pitch to distinguish between the meaning of words. Despite the global presence and typological ubiquity of tone, there has never been a systematic analysis of the principles that govern the evolution of tone systems. Linguists still do not have a complete phonetic, structural, and psychological model that explains how and why tones emerge (or fail to emerge) in language after language, and how they evolve once they are formed. This research is important because it contributes to our fundamental understanding of language variation and change. Understanding how languages do and don’t differ, and how they change over time, provides a way to better trace historical linguistic shifts, account for contemporary linguistic differences between groups, and understand the factors driving language evolution. Linguistic tone is just one feature of human language, but because it is such a common and widespread one, and because it has emerged so recently (relatively speaking) in so many languages, studying its emergence and evolution helps us understand the limits of language variation and change more generally.
The EVOTONE project had three objectives: first, to provide a new, empirically based foundation for the origin and typology of tone systems; second, to study how structural and phonetic factors interact in sound change; third, to develop the first empirically grounded set of principles for tonal evolution. We addressed these using a combination of linguistic fieldwork, acoustic-phonetic laboratory studies, and computational analysis of language data at scale, allowing us to developed a more nuanced understanding of how tone is produced and perceived. This is not only of abstract scientific interest, but will help drive substantial improvements to speech technology – automated recognition, understanding, transcription, and production of human speech – for millions of speakers of languages that are typically marginalized because they have linguistic characteristics, such as the interaction between tone and phonation, that are not addressed by mainstream, national-language technological development.
