My daughter is a fluent Welsh speaker. We live in Wales, in a town where there are a fair amount of Welsh speakers.
DD went to a storytelling/craft hour at the local library today. First session was in English, second was in Welsh. We chose the Welsh session and the lady doing it clearly loved what she was doing, she really got into character and the handful of children there were captivated by her.
The children's library is separate to main library and was, quite rightly so, open to children not listening to the story. Those that were were in a corner.
I was stood watching with another mum, when a lady rudely walked over to the storyteller and actually said this 'can you talk quieter as the other kids in the library are not deaf and don't want to listen to you talking like that'! 
I just stood there like a fish in sheer amazement. She then flounced over to by me and other mum and said to the other lady she was with 'I'd never send my kids to a Welsh school if that's how there going to sound' and made fun of the Welsh language.
She knew we could hear and I was really miffed and said I find that offensive.
She said she'd say what she liked and I said but other people can hear you and it's unpleasant.
She shrugged and flounced off. I'm still amazed hours later at her ignorance and rudeness. I'm wondering if I should have kept quiet or said more?
DD heard the rude lady and did ask why she'd said it but soon forgot about it. She also loved the session.