I've noticed that singers pronounce what I'll call the "h-mutation" differently in several recordings, and apparently in disregard of the spelling. So, Ciaran O Gealbhain in singing Casadh an tSúgáin pronounces féin as /hen/. In fact, in this recording, he seems to aspirate practically everything...a lovely sound, but confusing. He's from Co. Waterford. Does that impart a particular accent? In the same song, he very consistently pronounces liom as /ljaum/, a distinct "ow" sound, which is different from the Bothy band and Sean o Sé.