For me it means singing in your, "at home" voice. The voice or accent you use with your family. Here in Scotland most of us can speak a reasonable facsimile of "Queen's English," but that may not be what we sound like when "at home."

Sometimes when writing a song the language I use is more archaic, of the type used by my father, or grandparents. Unfortunately, the Scots are rapidly losing tha ability to speak Scots. The influence of a restrictive education system that enforced, "speaking properly" for the last two hundred years, and the saturation level influence of TV, and films, has all but put paid that. However, there are some heartening sign that all may not be lost.