"[9] However, American linguist Raleigh Ferrell reexaminates the Dutch materials and says "it appear that the Tevorangians were a distinct ethnolinguistic group, differing markedly in both language and culture from the Siraya."

The first Dutch visit to Tevorang appears to have been in January 1636 [...]"[1] Lee (2015) regards that, when Siraya was a lingua franca among at least eight indigenous communities in southwestern Taiwan plain, Taivoan people from Tevorangh, who has been proved to have their own language in "De Dagregisters van het Kasteel Zeelandia", might still need the translation service from Wanli, a neighbor community that shared common hunting field and also a militarily alliance with Tevorangh.

[10] The following is the phonology of the language:[11] It is likely that there were no /g/, /ts/, and /tsʰ/ in the 17th–19th century Taivoan, although Adelaar claims c preceding i or y be sibilant or affricate[12] and so could be /ts/ or /ʃ/.

However, the three sounds appeared after the 20th century, especially in Tevorangh dialect in Siaolin, Alikuan, and Dazhuang, and also in some words in Vogavon dialect in Lakku, for example:[13][14] The digraph ts recorded in the early 20th century may represent /t͡sʰ/ or /t͡s/: Some scholars in Formosan languages suggest it is not likely that /t͡sʰ/ and /t͡s/ appear in a Formosan language simultaneously, and therefore ts may well represent /t͡s/ as c does, not /t͡sʰ/.

It is hard to tell the actual stressing system of Taivoan in the 17th–19th century, as it has been a dormant language for nearly a hundred years.