Surreysinger: "I had an experience some months ago of standing up to present a serious and sad ballad, and had got half way through it... arriving at a very emotional point I was suddenly beset by what I can only describe as a strident mooing from the front row. One of the audience had decided to join in with me . Firstly, it threw me, and I promptly forgot my next line; secondly, it ruined the mood for me and chucked me out of the song (so to speak), and I spent the next three verses listening to the lowing and mooing getting noisier. It added nothing to my presentation,"

This made me laugh! I know the exact sound you mean, well I think near enough! Though not from life experience, only from having seen recordings of Folk performances and wondering "what on earth's that weird echoing rumble?" - "Ah!" realises I, as it gradually builds momentum, "it's members of the audience joining in.."
Genuinely, it sounded like a feild of sheep being herded (sans bleating, mostly). Horrible.

As far as others joining in when I'm singing, can't say I've noticed it happening much thus far. Thouhg I think it would depend on the type of song and how much thought I'd tried to put into such things as timing, ornamentation and phrasing as to whether it spoiled my own delivery. I do think I could get put off of a tragic ballad in particular if someone decided to join in.

As a *listener*, having heard some very fine 'light' singing, with beautifully delicate ornamentation, there are also times when others joining in someone else's singing would make me feel very unhappy. I love to hear the delicate artistry in a solo voice, and that would be lost with multiple joiners in. Also as a listener, I wouldn't join in for the most part, unless invited, or everyone else was already doing so. Though it also might depend on how intimately I personally knew the singer and their own rendition of the song in question. I did hear a performance of a song recently where the carefully crafted (and very important to the delivery of the song) timing was unfortunatly regularised by another member joining in and unwittingly controlling the tempo. So sensitivity is essential and respect for the efforts that others have put into their music really matters I think.