The sound system of the Thai language during the Ayutthaya period is uncertain due to a lack of systematic descriptions dating to before the 19th century. In this lecture, we’ll delve into the fascinating task of reconstructing the sound system of Ayutthaya Thai. We’ll explore various sources such as inscriptions, poetry, foreign transcriptions, and orthographical treatises to piece together the puzzle.

Our study suggests that the Thai language during the 417 years of the Ayutthaya Kingdom can be roughly divided into three periods. During the Old Thai period (14th-15th century), consonant sounds doubled the size of those in Modern Thai existed. However, during the Middle Thai period (16th century), they eroded, giving birth to a complex system of tonal distinctions in Early Modern Thai (17th century).