I understand. I agree the issue is the cognitive decline, but this is also a matter to "remain active", as you say. So I wish you remain active, and don't lose hope.

The objects you have in mind could also be reflections of people.

When you talk with someone, your brain builds an image if him inside. So you talk with the image of him inside you, not really with this person outside. So many objects could also be "images" of people. The brain tries to replicate reality inside , so that lot of things inside are actually copies of what is outside.

The voices will not go just like anyone has voices. The point is that "consciousness" means being expert of itself: if you lose this expertise , you cannot silence them, like everyone else is doing.

I think art could help you even more: think to have a school, it is a very good exercise about dissected mind. Also self-portraying could be a good exercise IMHO.