It does sound as if you're right, Guest AA - no amount of persuasion will work with this type of ignorant ill-mannered person (I know the type, unfortunately). If, as you say, the prime offender sulks if anyone dares whisper during his set, then obviously retaliation in kind, as I suggested earlier, is almost guaranteed to get results.

In the unlikely event of this failing to work, I would heartily recommend an assault on his person - the more violent, the better. Not that I'm violent by nature myself, you understand, and I would only do this as a last resort.

As for what to say while the ignorant person is performing, the more mundane and boring the conversation, the better. Here's an example to get you started:

Arrogant bastard folk singer (at the mic): And now, for your edification and extreme pleasure, I will sing my latest epic song, written only this morning on the bus. Although it has a chorus I would ask you not to sing as I would not want my voice to be drowned out by your inferior efforts. Please give it your utmost attention - I will be dropping several pins during this number to check. (starts intro on guitar)

Guest AA (loudly, to neighbour): I see the forecast for the next few days is unsettled, with rain coming in from the south west, and fog patches in the midlands.
Neighbour (equally loud): Yes, and it's predicted that the east coast will be showery with a risk of frost in low-lying areas. By the way, would you like one of these cheese and onion crisps? (rustles bag)
Guest AA: Why thank you - cheese and onion is one of my favourite flavours. I don't like Prawn Cocktail flavour though, do you? (crunches crisps loudly)
(etc.)