Why don’t you imply to your neighbour (in the upcoming chat) that several people in the street have been affected by it, and that ‘there are rumblings’.
I’ve had great success with this strategy. I stop short of saying ‘we’ve all been talking about you behind your back for weeks’ (if we haven’t), but it’s so easy for people to dismiss just one complaining neighbour. They just write you off as a nutter. Harder to ignore the whole estate or street.
I mean, it’s not a huge leap that all sorts of people are annoyed by The Beeping, so they likely are all grumbling behind their curtains.
There are people who just don’t care about other people’s opinions at all, but most realise that keeping their neighbourhood friendly towards them makes life easier overall. Even if your neighbour doesn’t care about being ‘liked’, she might care about never being able to borrow a cup of sugar, or get emergency help, etc.
I’d give it a go. Show her the legislation and say you thought it was more honest to bring it to her attention directly, than grumble as a group. Wave a hand vaguely around the street. Smile, depart. Worth a try?