I have written before of my grandmother and her various issues (knee replacement, not bathing, living on her own, etc) but after her coming over, I really noticed something that I haven't really paid attention to before. She can't shut up and can't tolerate silence. When she is over, the TV is blaring and she is nonstop talking. If the TV isn't on, she demands that it be turned on, if we tell her that it isn't working correctly and we are not going to try and fix it that moment, she just talks, loudly. Is it her age of 87 that makes her so afraid of peace and quiet? If I am over her house, the TV is blaring and I mean blaring. During the day when I am alone, I don't have the TV on and I enjoy silence but sometimes when I am alone, I will have the TV on until I'm ok.
I know a man who has bipolar disorder. He can't stop talking! He repeats himself and makes the same points over and over. Grrr.... he is very hard to talk to. But he is a kind and generous soul and he does have friends. This talking thing has improved a lot since he has been through therapy and is on a good drug regime.
I have two other friends who talk a LOT. They seem self-centered to me. I wonder if they are "afraid" of silence or if some other small impairment causes this.
I am an introvert and I like silence. But now that I live alone I find I often like music playing. It makes me feel less isolated. It is a small connection to the rest of humanity. I may be alone, but here is a connection to a composer who lived two hundred years ago and an announcer who is talking to lots of other people out there.
I would not try to change GM's habits when she is on her own. But for your own comfort when you are with her, try some of the suggestions in other posts.
Perhaps you could substitute CDs for the TV. I don't even know if CD players can still be bought b/c so much entertainment has become device based, but if you can get one of the multi-CD players, you could stack it with CDs that would provide a few hours of entertainment.
Write out very detailed instructions so she can change the CDs and keep the music coming.
If you're there in the evening, put on some soothing CDs. There are a variety of calming, restorative and restful CDs that can be therapeutic. My sister had one of sounds of waves washing ashore. It may sound boring, but the rhythm is very soothing. Harp music is also peaceful and calming.
Or get CDs of her favorite singers.