Armas Otto Aapo Väisänen (9 April 1890 – 18 July 1969)[1] was an eminent Finnish scholar of folk music, an ethnographer and ethnomusicologist.

In the early twentieth century he documented, in recordings and photographs, traditional Finnish and Finno-Ugric music and musicians.

[3] With a scholarship from the Finno-Ugrian Society Väisänen traveled to Russia in 1914 to collect Finno-Ugric folk melodies.

[1] A. O. Väisänen's dissertation was presented in 1939 on Ob-Ugrian folk music in German: Untersuchungen über die Ob-ugrischen Melodien: eine vergleichende Studien nebst methodischer Einleitung.

[1] Between 1926 and 1957 Väisänen hold the position of the head of the folk music department at the Sibelius Academy, Helsinki, Finland.