Estonian aa: A multifunctional change-of-state token

•Estonian aa claims both information receipt and understanding.•Estonian aa is used in all sequential positions: the first, second, and third.•Aa marks an independent change-of-state as well as change due to the previous turn.•Aa marks revised understanding and sudden recollection, whereas ahah and ahhaa does not.

The aim of the article is to show that Estonian aa is a multifunctional change-of-state particle. The audio data comes from the Corpus of Spoken Estonian of the University of Tartu and comprises 204 instances sourced from face-to-face conversations as well as phone calls, including both everyday and institutional interaction. As a response to the information given in the prior turn, aa functions as a marker of understanding in four contexts mentioned in the previous literature. Aa indicates change from not-knowing to now-knowing as a response to information and to question-elicited information, the solution of the problem in a repair sequence and change from being wrongly informed to rightly informed. In addition, aa is used as a marker of sudden recollection. We introduced a new kind of change-of-state not described in literature: aa as a marker of delayed realization. In the first position, we described four functions of aa: a marker of independent now remembering, independent noticing, successful outcome of a search, and a new variant of independent delayed realization. Our analysis indicates that participants rely on the sequential position of aa to determine the change-of-state functions. We compare the usage of aa with the change-of-state tokens of English, German and Finnish.