But there are singers (Jeannie Robertson and Lizzie Higgins to name but two, plus other current singers) who seem to have access to a wider range of effects -- snap notes, pauses, leaps, slurs and, inevitably, some twiddles -- which are used to point up the text of a song.

Here we have someone, Anne Neilson, who really understands the point of it all, though obviously the fact that she is talking about two of my all-time heroes obviously helps.
I spent a lot of time in the company of both Jeannie and even more with Lizzie who stayed in our house when she was on the tours that we organised for her. To my ears, both these fabulous singers structured their conversations in the same way. All the effects that Anne describes in the admirable way in the sentence that I quote above were present in the way they spoke as well as in the way they sang. Both would sometimes makes a single syllable word into two- or three- beats if it was useful to help them make their points. As speakers and more particularly as story-tellers their use of the pause was dramatic and effective and if they wanted to emphasise a particular word they would slow down and emphasise it.
All the Scots travellers seemed to be happier talking about themes by use of particular examples rather than talking about a subject in a more general way; in a vacuum so-to-speak. I remember in particular a conversation with another hero, Jane Turriff, about men 'bad-using' women and Jane quoted several examples of people amongst her neighbours in Fetterangus and she went on to pour scorn on the man who treated someone called Annie badly. It took me some time to realise that she was talking about her song, Mill O'Tifty's Annie. It brought home to me that they did not just sing their ballads; they lived them. I think that is why I found their ballads to utterly convincing.