| Armas Otto Aapo Väisänen | |
| Birth Date: | 9 April 1890 |
| Birth Place: | Savonranta, Grand Duchy of Finland, Russian Empire |
| Death Place: | Helsinki, Finland |
| Nationality: | Finnish |
| Other Names: | A. O. Väisänen |
| Known For: | folk music |
| Occupation: | scholar |
Armas Otto Aapo Väisänen (9 April 1890 – 18 July 1969)[1] was an eminent Finnish scholar of folk music, an ethnographer and ethnomusicologist.[2]
Väisänen was born in Savonranta. 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.[4] He made field trips to Mordovia, Ingria, Veps, Russian Karelia.[1] His activities also marked the a new stage in the history of collecting Seto folk songs in Southern Estonia.[5] After the first trip in 1912 he made 6 fieldtrips to Estonia between 1912 and 1923.[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.[1] He was the professor of musicology at University of Helsinki from 1956 to 1959. He died in Helsinki, aged 79.