Hymns and psalms can be sung in Gaelic in the same way that they are sung in English at church. There is a very powerful old style of unaccompanied psalm singing called 'precenting' which is still heard in some Gaelic presbyterian churches.
The style stems from the 16th-century Reformation of the church, which established the protestant Christian faith and which encouraged worship in a person’s native tongue (rather than Latin) and expressions of worship by individuals as well as the clergy and choir. Because few people would be able to read, a call-and-response style evolved in protestant churches and in Gaelic Scotland this developed into the style of psalm singing you can still hear today. It is one of very few cultures where this particular call-and-response style of worship still exists.
Each line of the psalm is 'put out' by the precentor or leader. The congregation then joins in gradually and slowly sings those words, but with varying degrees of ornamentation and at varying speeds. Although each singer is singing the same tune, the effect is of a continuous sound with different chordal effects being created. This is known as heterophony.
Although the music sounds very complicated, the roots of the melodies being sung lie in straightforward Scottish metrical psalm tunes.
Alasdair Graham and a congregation on the island of Lewis sing the original melody.
'Martyrs' performed by Alasdair Graham and Congregation
From Psalm 79, vv 3 and 4, Gaelic Psalms from Lewis, Greentrax CDTRAX9006, Track 6