Quick background, mom is 80 years old with midstage Alzheimer's. She's able to do many things with direction and limited help on my part; bath, dress, eat. She's mobile and loves to be out. We go out to eat a couple of times a week and shopping almost every day, we may only pick up a loaf of bread but it gets her out of the house. Also, getting out helps keep my sanity!
A couple of months ago she started making noises and talking to herself. Lots of noises when eating at home, less when eating out. Because of this I've started giving a lot of thought to where we go, trying to go places when it's not busy so we/she doesn't bother anyone. She's not rude towards anyone or loud, the talking to herself are things like "oh my, geez".
It occurred to me yesterday that I've never noticed this kind of behavior in other seniors when I've been out. I'm wondering if I'm trying to hard to keep her in "normal" society?
At this point I'm trying to keep her engaged and happy knowing at any time things will change and she won't be able to go out.
So long as you can manage it and she is enjoying it, KEEP DOING IT! Too many become reclusive. Dad did and then later mom started making excuses not to join the other ladies at the Senior Center hooplas, trying to cancel doctor appointments or refusing to go, etc. Back when she lived alone still and even now in MC she might light up if you mention going out somewhere to eat, even something like pizza or she might suggest it (really mom? you JUST ate!) Anything else? Nope, especially doctor/dentist appointments!
As far as odd behavior, noises, etc, do you ever go shopping when people bring their kids? The obnoxious ones who the parents don't watch over??? When my kids were a little older, maybe preteen, they would see these kids who were unsupervised behaving badly and ask if they were like that. My response was a resounding NO, and followed up with 'If you were like that, I wouldn't bring you along!'
We actually were eating at a fast food place once where a man (adult, not elderly, not dementia) kept making the most loud obnoxious noises, like trying to get something up and grossed my daughter out so much she refused to eat anymore! Perhaps he had a medical condition, perhaps he just had something stuck somewhere, but it was very loud and nasty! There was no way to block it out or ignore it. Otherwise, most of the time people are, as others noted, wrapped up in their own business or conversations and don't notice much going on around them. It isn't like your mom is loudly blurting out obscenities. You could choose times where there might be fewer people around, however less people = less background noise, so mom's mutterings might be even more noticeable. You can explain if you want to, but if they don't ask, I wouldn't bother.
I would just keep taking her out and enjoy the times you have left with her! It does, so the experts say, help keep the mind engaged and can defer the inevitable for a little while longer.
I wish we could take mom out more. It was hard enough before when she was using a walker, but after a few non-injury tumbles she started refusing to walk, has trouble even standing up and I cannot support her weight. Keep on taking mom places - you won't regret it! If it becomes too much in "busy" places (sometimes the noises, lights, people, etc can bring on some anxiety), stick to walking in the neighborhood or a nice park. If/when she has trouble walking, you can try using walkers, rollators or transport chair.
But, whatever the occasion, having pix allows for some fond memories (and even reminders that Yes mom, we remembered your birthday, even when you insist you don't have any birthdays anymore - see here, we celebrated it with you! I make sure to get the age numbers showing too!)
As for onlookers-pffft-screw them. This is her normal right now. That's all that matters and as for society-Normal normal is overrated. I would rather sit next to you and your Mother in a restaurant with her mumbling or making some noises than next to a bunch loud obnoxious a**holes any day.
mom used to say she wasn't a house plant
I enjoy seeing seniors out with their daughters or caregivers. (or sons if ever I would see that.) Lunch is very busy at some places.