Singing in three is an older female polyphonic traditional singing that has survived to this day in the ethnographic area of ​​Usora, part of Bosnian Posavina.

The name “in three” refers not only to the number of performers, but also clearly suggests that a three-voice harmony is heard, one voice “begins” while the other two “follow” clearly separated in their sections, which is a rarity in Bosnian-Herzegovinian rural vocal practice. Namely, the appearance of a three-voice harmony is a unique musical phenomenon in rural vocal practice and differs significantly in terms of the treatment and experience of intervals from other polyphonic vocal forms in Bosnia and Herzegovina.

Songs of this type are performed on various occasions, but always as an invitation to a prelo. Then, along with the verses, the name of the host or hostess where the prelo is being convened is usually stated.