My 9 year old makes much less noise than her brother did at 4!
And a mature student concentrates by going to their room where it's quiet. If I'm buying a house with renting a room in mind, I'll make sure it's suitable, obviously!
In our old place, the rooms we rented out were on their own floor, and you couldn't hear noise in the front room from there. It was a good set up.
Also, anyone who's really intolerant of noise isn't going to rent a room in a family house, are they?! It's really important to find a good fit when interviewing people for rooms. It's totally different to interviewing people for jobs - instead of ignoring any prejudices you have, you need to embrace them and be really frank about them IMO.
e.g. if you can't stand people who leave mess around, then say so. I'm the opposite, mess doesn't really bother me that much and I need to have lodgers who don't mind a little clutter. I am honest about this and had people not move in on this basis. Which is great - it wouldn't have worked. I turned someone down as they were very religious (evangelical Christian) and wanted to play religious music in the house. Lovely young woman. She wasn't right for us, though.
It used to be very normal for people have big families and to live with extended family, it's very recent, this idea of only the nuclear family being the norm in a house. I do understand that loads of people really love that, and that's fine. But there are other people out there who like living with lots of other people around.
We never had a problem finding students to rent our room. None of them were looking for a family home as such, but were happy to live with a family and chose our place for other reasons. Of course many would hate it! But luckily there were enough who didn't to make it viable.