The characteristics of the Gaelic language itself, and its unique features such as vowel length, have contributed to the distinctiveness of Gaelic music. This is not just confined to the Gàidhealtachd itself, as many Gaelic airs, for example, were used by Lowland poets such as Robert Burns. There is evidence which suggests that the most unique characteristic of Scottish music, the ‘ScotchSnap’ originates in Gaelic speech.