Puirt à beul (pronounced [pʰurˠʃtʲ a ˈpial̪ˠ], literally "tunes from a mouth") is a traditional form of song native to Scotland (known as portaireacht in Ireland) that sets Gaelic lyrics to instrumental tune melodies. Historically, they were used to accompany dancing in the absence of instruments and to transmit instrumental tunes orally. 

Wikipedia

Maybe also the irish form of it as a genre